JP5332173B2 - Image display control device - Google Patents

Abstract

An image display control device, a driving device of an electric optical device having the same, and an electronic device having a control device, a driving control device, and an image control device are provided to acquire various statistics information on moving pictures efficiently while simplifying circuit configuration. A statistics information acquiring unit(212) acquires statistics information on an image signal every one frame. An operator generates a compensation coefficient used for compensating the image signal by using the statistics information related to the previous frame outputted from the statistics information acquiring unit. An image compensator compensates the image signal by using the compensation coefficient. The statistics information acquiring unit includes statistics units(EX0~EX255) consisting of a comparator(1) comparing brightness of the image signal with reference brightness((0)~(255)) and outputting the comparison result and a statistics value buffer(4) updating a count value in accordance with the comparison result, and a statistics value operating unit calculating a predetermined statistics value based on the count value of the statistics value buffer. The reference brightness is differently set in each statistics unit. The image signal is inputted to each statistics unit in parallel.

Description

  The present invention relates to an image display control device and the like, and more particularly to an image display control device and the like that acquire statistical information of an input image and adaptively correct an image based on the acquired statistical information.

  Patent Documents 1 and 2 disclose a technique for correcting a still image based on a statistical value of the still image.

  Patent Document 3 discloses a technique for adjusting image data so as to reduce the amount of light emitted from the backlight for power saving while increasing the transmittance of the liquid crystal display screen as much as possible.

Patent Document 4 describes an image correction apparatus that uses a look-up table (LUT) to correct a luminance signal of a display image.
JP 2004-200904 A JP 2005-108194 A JP-A-11-65531 JP 2004-310671 A

  In order to adaptively correct a moving image based on a statistical value, it is necessary to acquire the statistical value of the moving image efficiently and at high speed.

  In particular, in order to perform adaptive correction of moving images to reduce illumination (backlight etc.) and prevent deterioration of image quality at the same time, it is necessary to perform enormous calculations based on various acquired statistical values. . Therefore, it is an essential technique to efficiently and quickly acquire various statistical values used for the calculation.

For example, in order to appropriately correct a moving image, it may be necessary to acquire not only the luminance statistical value of the input moving image but also the color difference statistical value in real time. In addition to the maximum value, minimum value, and standard deviation value of luminance, it may be necessary to acquire the average value of luminance, the average value of color difference , and the like in real time. In these cases, the statistical value acquisition operation becomes more complicated, and the circuit configuration of the statistical information acquisition unit (histogram creation unit) becomes more complicated.

  In addition, in the arithmetic processing when light reduction and image correction are performed at the same time, there is a method of simplifying the arithmetic processing using a lookup table (LUT) storing the arithmetic results, but it takes time to access the memory. Accordingly, for example, when a streaming video by one-segment broadcasting (digital broadcasting for a mobile phone terminal) is played back on a mobile phone terminal such as when real-time performance is required, a method using an LUT is not suitable.

On the other hand, when a predetermined operation is performed in parallel by a plurality of dedicated hardware, high speed (real time) can be ensured, but the area occupied by the circuit increases and the power consumption of the circuit increases.

In this way, for real-time adaptive correction of moving images (especially for performing illumination dimming and image correction for image quality compensation accompanying dimming simultaneously), statistical information acquisition and statistical information Real time performance is required for both of the operations used, and an increase in circuit scale and low power consumption are also required. The prior art cannot respond to such a request.

  The present invention has been made based on such consideration. According to some aspects of the present invention, for example, various statistical information of a moving image can be acquired at high speed and efficiently while preventing the circuit configuration from becoming complicated, and the calculation using the statistical information is also performed at high speed. And can be executed efficiently. As a result, for example, while achieving low power consumption and suppression of increase in circuit scale, highly accurate images that have not been used in the past to compensate for adaptive illumination dimming and image quality degradation associated with the dimming. Correction can be realized at the same time.

  An image display control apparatus according to the present invention is an image display control apparatus that corrects an image signal based on statistical information, the statistical information acquisition unit that acquires the statistical information of the image signal for each frame, and the statistical information Using the statistical information about the previous frame output from the acquisition unit, an arithmetic unit that generates a correction coefficient used for correction of the image signal, an image correction unit that corrects the image signal using the correction coefficient, And the statistical information acquisition unit compares a luminance of the image signal with a reference luminance and outputs a comparison result, and a statistical value buffer that updates a count value according to the comparison result. A plurality of statistical units configured to include a statistical value calculation unit that calculates a predetermined statistical value based on a count value of the statistical value buffer that is output from each of the plurality of statistical units. The reference brightness in each of the plurality of statistical units are set to values different from each other, and wherein the each of the plurality of statistical units the image signal is input in parallel.

  In each of the statistical units configured to update the count value by comparing the luminance of the image signal with the reference luminance value, the image signal is input in parallel, and the count value of the luminance is updated in parallel in each statistical unit, Thus, the brightness count value is acquired at an extremely high speed. The reference luminance value in each statistical unit is set to a different value. The statistical value calculation unit takes in the luminance count value output in parallel from each statistical unit, and calculates a statistical value necessary for image correction at high speed. Thereby, it is possible to acquire a statistical value about a moving image (for example, streaming video) in real time.

  In one aspect of the image display control device of the present invention, the statistical value calculation unit included in the statistical information acquisition unit is a luminance maximum value / minimum value detection unit that detects a maximum value and a minimum value of luminance of an image signal. And a standard deviation computing unit for obtaining a standard deviation value, and each of the luminance maximum value, the luminance minimum value and the standard deviation value obtained by the calculation is supplied to the computing unit.

  Since the luminance distribution of an image of one frame can be estimated by the maximum value / minimum value / standard deviation value, the statistical value calculation unit obtains the above three values.

Further, in another aspect of the image display control apparatus of the present invention, the statistical information acquisition unit further acquires each statistics blue color difference and red color difference included in the image signal.

For image correction, in which consideration of a case where it is necessary statistical information of the color difference not only luminance statistics were as statistics blue color difference (Cb) and red color difference (Cr) can also be acquired.

Further, in another aspect of the image display control apparatus of the present invention, the statistical information unit includes, as a structure for obtaining each of the statistical information of the blue color difference and the red color difference, cumulatively adds the luminance of each pixel addition a vessel, a luminance total value buffer for storing the accumulated value, the brightness sum value unit including an adder for cumulatively adding the blue color difference of each pixel, and blue color difference sum buffer for storing the cumulative sum , and blue color difference sum unit comprising, an adder red chrominance of pixels cumulative addition, and red chrominance sum unit including a red color difference sum buffer for storing the accumulated value, and the obtained brightness sum value, on the basis of the blue color difference sum value and the red color difference sum value, with the brightness average value, the average calculation unit for calculating each of the blue color difference average value and the red color difference average value.

A moving image of one frame, the average luminance, red chrominance (Cr) average, is obtained by clarifying the configuration for obtaining the blue color difference (Cb) average. That is, the luminance, red chrominance, prepared sum unit corresponding to each of the blue color difference, the total unit is basically constituted by an adder and a register. The structure of each total value unit is simplified and has the same kind of structure as the above-described statistical value unit for obtaining the luminance statistical value, and therefore, both units are laid out with high density. Can do. The average calculation section luminance outputted in parallel from the sum unit, red color difference is calculated at high speed, each of the average value based on the sum of the blue color difference.

  In another aspect of the image display control apparatus of the present invention, when the acquisition of statistical information is unnecessary, the statistical information acquisition operation in the statistical information acquisition unit is stopped.

  In the above-described statistical information acquisition unit, the units are operated in parallel so that statistical values can be acquired at an extremely high speed. Therefore, it is inevitable that the power consumption slightly increases. However, when it is clear that statistical information is unnecessary (for example, when playback of a moving image is stopped because the pause button is pressed), consumption of the statistical information is stopped by stopping the acquisition operation at the same time. Electric power can be reduced.

  In another aspect of the image display control device of the present invention, when the acquisition of statistical information is unnecessary, the counting operation of the statistical value buffer included in each of the plurality of statistical units is stopped.

  This clarifies that the statistical value buffer stops the luminance value counting operation to reduce the power consumption.

  In another aspect of the image display control apparatus of the present invention, a gate circuit for controlling supply / non-supply of the operation clock to each of the statistical value buffers is provided, and the operation clock from the gate circuit is provided. Output / non-output is switched by the first enable signal.

  It is clarified that clock gating using the first enable signal and the gate circuit is executed in order to stop the luminance value counting operation in the statistical value buffer. The supply / non-supply control of the operation clock can be easily performed, the circuit configuration is not complicated, and the realization is easy.

In another aspect of the image display control device of the present invention, when the acquisition of statistical information is unnecessary, the counting operation of the statistical value buffer included in each of the plurality of statistical units is stopped, and the luminance total value buffer, stopping the blue color difference sum value buffer and the count operation of the red color difference sum buffer.

In addition to statistics buffer for counting the brightness value, by stopping luminance total value buffer, a blue color difference sum value buffer and the count operation of the red color difference sum buffer all at once, is to effectively reduce the power consumption . Since each buffer has the same type of configuration and is common in that it counts in synchronization with the clock, it is possible to easily stop the count operation by stopping the supply of the common operation clock. It is.

Further, in another aspect of the image display control apparatus of the present invention, provided the gate circuit for supplying an operation clock to each of the luminance total value buffer, the blue color difference sum buffer and the red color difference sum value buffer, the The output / non-output of the operation clock from the gate circuit is switched by the second enable signal.

Brightness sum value buffer, in order to stop the counting operation in the blue color difference sum value buffer and the red color difference sum buffer is obtained by a clearly points to perform clock gating utilizing the second enable signal and a gate circuit . The supply / non-supply control of the operation clock can be easily performed, the circuit configuration is not complicated, and the realization is easy.

  In another aspect of the image display control apparatus of the present invention, the arithmetic unit uses the statistical information of the previous frame to dimm the illumination for image display adaptively according to the image signal. The illumination luminance after dimming when the control is executed is also calculated, and the correction coefficient used for correcting the image signal for compensating for the image quality degradation accompanying the dimming of the illumination is generated.

  The computing unit also calculates the illumination brightness after adaptive dimming using the calculated statistical value, and calculates a correction coefficient necessary for image correction to compensate for image quality deterioration due to the dimming The point is clarified.

  In another aspect of the image display control device of the present invention, a code storage unit storing a plurality of codes for designating an operation procedure of the computing unit, and the code stored in the code storage unit A sequence instructing unit that controls an output order; and a decoder that decodes the code output from the code storage unit and generates at least one of an instruction and data to be supplied to the computing unit.

  It has been clarified that the adaptive dimming processing and image correction processing of illumination are realized by real-time computation using a common computing unit (shared computing unit). By the calculation, the correction coefficient for image correction and the illumination brightness after dimming are calculated in real time, and image correction using the calculated correction coefficient is executed. The operation of the shared arithmetic unit is controlled by microcode that encodes the signal processing procedure. By using a common computing unit, real-time computation is possible without the need to install the same type of hardware in parallel, and high-speed dimming control and image correction can be realized with the minimum circuit and minimum power consumption. it can.

  In another aspect of the image display control apparatus of the present invention, the arithmetic unit includes first and second multiplexers, an arithmetic logic unit, and a distributor that distributes the arithmetic results of the arithmetic logic unit. The decoder supplies a coefficient to the first and second multiplexers, an arithmetic instruction to the arithmetic logic unit, and distribution information to the distributor.

  An example of a specific configuration of the shared arithmetic unit is clarified, and what instruction or data is supplied to each component is clarified. That is, in this aspect, a shared arithmetic unit is configured by a plurality of multiplexers, an arithmetic logic unit (ALU), and a distributor. Coefficients used for calculation are supplied to the multiplexer, instructions (opcodes) are supplied to the ALU, and distribution destination information is supplied to the distributor.

  In another aspect of the image display control device of the present invention, the computing unit further feeds back a plurality of output destination registers and at least a part of signals accumulated in the plurality of output destination registers to the input side. And a return path.

  In another aspect of the image display control apparatus of the present invention, the shared arithmetic unit further feeds back to the input side a plurality of output destination registers and at least some of the signals accumulated in the plurality of output destination registers. And a return path to be made.

  This clarifies that the shared arithmetic unit has a feedback path for returning the operation result to the input side. Accordingly, for example, first, the illumination brightness after dimming is obtained by the first computation process, the computation result is returned to the input side, and the correction coefficient of the image is obtained based on the obtained illumination brightness. Processing becomes possible. In addition, since the shared arithmetic unit has a feedback path, it is possible to perform a cyclic (IIR) filtering process.

  In addition, the electro-optical device driving device of the present invention includes an image display control device.

  The image display control device (image display control LSI) of the present invention is mounted on a drive device (driver) of an electro-optical device (including a liquid crystal display device). The image display control device (image display control LSI) of the present invention has the characteristics that it can process moving images such as streaming images in real time, has excellent power saving, and can be miniaturized. Therefore, the added value of the driving device (driver) is improved.

  The control device for the electro-optical device of the present invention is equipped with the image display control device of the present invention.

  The image display control device (image display control LSI) of the present invention is mounted on a control device (controller) of an electro-optical device (including a liquid crystal display device). The image display control device (image display control LSI) of the present invention has the characteristics that it can process moving images such as streaming images in real time, has excellent power saving, and can be miniaturized. Therefore, the added value of the control device (controller) is improved.

  The drive control device for the electro-optical device of the present invention is equipped with the image display control device of the present invention.

  The image display control device (image display control LSI) of the present invention is mounted on a drive control device (device in which a driver and a controller are integrated) of an electro-optical device (including a liquid crystal display device). The image display control device (image display control LSI) of the present invention has the characteristics that it can process moving images such as streaming images in real time, has excellent power saving, and can be miniaturized. Therefore, the added value of the drive control device (device in which the driver and the controller are integrated) is improved.

  The electronic device of the present invention is equipped with the image display control device of the present invention.

  For example, by mounting the image display control device (LSI) of the present invention on a mobile terminal (including a mobile phone terminal, a PDA terminal, and a portable computer), a streaming image such as one-segment broadcasting can be displayed with high image quality. And a longer battery life can be realized.

According to at least one embodiment of the present invention, for example, the following effects can be obtained. However, the following effects are not always obtained, and the following list of effects should not be used as a basis for unduly limiting the present invention.
(1) By inputting image signals in parallel to each of the statistical units and simultaneously updating the luminance count value in each statistical unit, the luminance count value can be acquired at an extremely high speed.
(2) In addition, by also acquiring statistical information of the color difference not only luminance of the statistical information enables adaptive image correction based on color differences.
(3) Since the statistical unit and the total value unit are compact circuits and have the same configuration, a high-density circuit layout can be realized.
(4) When it is not necessary to acquire statistical information, useless power consumption can be eliminated by stopping the counting operation of the statistical unit and the total value unit. Since the statistical value unit and the total value unit have the same configuration that operates with a common operating clock, for example, the counting operation can be easily stopped by stopping the common operating clock by gating. it can.
(5) For image display control in the case of performing adaptive dimming of the backlight for power saving and adaptive image correction for preventing image quality deterioration accompanying the dimming simultaneously, By applying the technology, it is possible to realize advanced calculations based on statistical values in low power consumption and in real time.
(6) By using an arithmetic unit of a microprogram control system, real-time computation can be performed without providing the same kind of hardware in parallel, and high-speed adaptive dimming control and adaptive image can be achieved with minimum circuitry and minimum power consumption. Correction can be realized.
(7) By simultaneously executing adaptive dimming processing and image correction, power consumption can be significantly reduced by adaptive dimming of illumination brightness while minimizing image quality degradation (up to 30% reduction) Has been confirmed). Further, since it can be realized with a minimum amount of hardware, space can be saved. Further, even in the processing of moving images such as streaming video, no delay time occurs, and real-time and highly accurate processing is realized.
(8) A high added value of a drive device (driver) such as a liquid crystal display device, a control device (controller), and a drive control device (device in which a driver and a controller are integrated) can be realized.
(9) By displaying the image display control device (LSI) of the present invention in a mobile terminal (including a mobile phone terminal, a PDA terminal, and a portable computer), streaming images such as one-segment broadcasting can be displayed with high image quality. In addition, the battery life can be extended. (10) Real-time video image correction based on statistical values, and adaptive illumination dimming for power saving, and adaptive image for preventing image quality degradation due to this dimming Even when correction is performed at the same time, real-time performance, circuit scale reduction, and low power consumption can be realized.
(11) A technique for acquiring moving image statistical information at high speed and with low power consumption can be provided.
(12) Various statistical information of moving images can be acquired at high speed and efficiently while preventing complication of the circuit configuration, and further, calculation using statistical information can be executed at high speed and efficiently. As a result, for example, while achieving low power consumption and suppression of increase in circuit scale, highly accurate images that have not been used in the past to compensate for adaptive illumination dimming and image quality degradation associated with the dimming. Correction can be realized at the same time.

  The present invention can be widely used as a technique for acquiring moving image statistical information. However, the present invention is an important technique for securing the real-time property when performing adaptive dimming of illumination for power saving and image correction for compensating image quality degradation based on the dimming simultaneously. It is. Therefore, the contents of adaptive dimming control and image correction according to the display image will be described with reference to FIGS. 1 to 10, and then the specific configuration of the statistical information acquisition unit will be described.

(First embodiment)
(Relation between light control and image correction)
1A to 1C are diagrams for explaining the contents of adaptive dimming control and image correction according to a display image employed in the image display control apparatus (image display control LSI) of the present invention. FIG.

As shown in FIG. 1A, in the embodiment of the present invention, adaptive image correction of a liquid crystal panel (LCD) 10 and adaptive correction of luminance of an illumination (LED: hereinafter referred to as backlight) 12 ( Adaptive dimming) at the same time. In the figure, Gy ′ is an enhanced image correction amount in the case of dimming. This Gy ′ is obtained by adding the image correction amount enhancement amount ΔGy accompanying dimming to the image correction amount Gy when there is no dimming. Gs is a correction amount of the luminance of the backlight 12 due to adaptive dimming.

  FIG. 1B shows the image correction amount Gy when there is no light control. That is, Gy is an image correction amount when the luminance of the backlight 12 is fixed. For example, a correction that raises the luminance is performed on a portion where the luminance is low, and a correction that reduces the luminance is performed on a portion where the luminance is too high.

  FIG. 1C shows the enhancement amount ΔGy of the image correction amount accompanying the light control. Since a dark image is less susceptible to the dimming of the backlight 12 than a bright image, in principle, the dimming amount of the backlight 12 increases in the case of a dark image. However, since the luminance of the display image decreases with dimming, the image correction is strengthened to compensate for the luminance decrease. ΔGy is an image correction enhancement accompanying dimming (Gs).

  In the present invention, as shown in FIG. 1 (A), the backlight 12 is actively dimmed to save power, while the normal image quality is compensated for the image quality degradation accompanying the dimming. The final image correction amount Gy is determined by adding the enhancement (ΔGy) of the image correction amount associated with the light control (Gs) to the image correction amount (Gy).

(Adaptive dimming of image correction amount)
FIG. 2 shows a backlight reduction rate, an image correction amount (Gy) without dimming, an image correction amount (Gy ′) with dimming, and dimming with respect to the average luminance (Yave) of an image of one frame. FIG. 6 is a characteristic diagram illustrating a change in an image correction amount enhancement amount (ΔGy) associated with FIG.

  In the figure, the characteristic line A indicates the characteristic of the backlight luminance reduction rate (%), the characteristic line B indicates the characteristic of the image correction amount (Gy) without dimming, and the characteristic line C indicates dimming. The characteristic of the image correction amount (Gy ′) in the case of being present is shown, and the characteristic line D shows the characteristic of the enhancement (ΔGy) of the image correction amount accompanying the light control.

  First, attention is focused on the characteristic line A indicating the change in the backlight luminance reduction rate. Obviously, the lower the average luminance (Yave), the higher the backlight luminance reduction rate, and the lower the average luminance (Yave), the lower the backlight reduction rate. This is because the higher the average brightness, the greater the effect of backlight dimming.Therefore, for images with a low average brightness, priority is given to power saving and the light is greatly reduced. This is a result of diminishing a small amount in order to give priority to suppression.

  Next, attention is paid to the characteristic line B indicating the change in the image correction amount Gy when there is no light control. As shown in the figure, until the average luminance value Gammath1, almost fixed luminance increase correction is performed, and when the average luminance value increases, the amount of increase in luminance decreases, and when the average luminance value becomes larger than the average luminance value Gammath2, Correction for reducing the brightness is executed. That is, basically, when the average luminance is low, correction is performed to increase the luminance, and when the average luminance is too high, correction is performed to decrease the luminance.

  Next, attention is paid to a characteristic line C indicating a change in the image correction amount Gy ′ when light adjustment is performed. Obviously, the lower the average luminance, the larger the image correction amount, and the higher the average luminance, the smaller the image correction amount. In addition to determining the image correction amount on the basis of the characteristic line B, this further enhances the image correction amount on the low luminance side in order to prevent image quality deterioration on the low luminance side where a large light reduction rate is set. It is necessary.

  Next, attention is focused on the characteristic line D indicating the change in the amount of image correction enhancement (ΔGy = Gy′−Gy) associated with dimming. As described above, the enhancement amount ΔGy of the image correction amount associated with the light control increases on the low luminance side and gradually decreases as the luminance value increases. However, the enhancement of the image correction amount gradually increases from around the average luminance value Gammath3. This is because, as the brightness of the backlight 12 is diminished, the higher the brightness of the image, the lower the image quality, so it is necessary to further enhance the image correction in order to suppress the reduction of the brightness of the image having a high average brightness. is there.

(Relationship between power saving strength and ΔGy)
FIG. 3 is a diagram showing how the characteristic line of the image correction amount enhancement (ΔGy = Gy′−Gy) accompanying light adjustment changes according to the luminance reduction rate of the backlight. In FIG. 3, a characteristic line A shows a characteristic line when power saving is high (backlight luminance reduction rate 30%), and a characteristic line B shows a characteristic line when power saving is low (backlight luminance reduction rate 10%). A characteristic line C indicates a characteristic line in the case of normal power saving (backlight luminance reduction rate 20%).

  As described above, in any of the characteristic lines, the enhancement amount ΔGy of the image correction amount accompanying dimming tends to increase on the low luminance side and gradually decrease as the luminance value increases. In the high region, ΔGy tends to gradually increase again. Further, as the power saving performance is enhanced and the luminance reduction rate of the backlight is increased, the image correction amount enhancement amount ΔGy associated with the light control is also increased.

(Enhancement of saturation correction)
Dimming the backlight reduces the saturation across the screen. Therefore, saturation correction is performed so that the saturation before and after dimming is preserved. Basically, the saturation is corrected according to the following equation (1). In the following equations, it is shown only for the blue color difference (Cb), the same for red chrominance (Cr).
Cb [cb] = Fc × Gc + c b (1)
In the above equation (1), cb is a saturation correction input color difference, Cb is a saturation correction output color difference, Gc is a saturation correction amount, and Fc is a saturation correction coefficient curve.

4A to 4C are diagrams for explaining saturation correction. FIG. 4A shows the output color difference (Cb or Cr) with respect to the input color difference (cb or cr). In the figure, the difference between the characteristic line indicated by the solid line and the straight line indicated by the dotted line corresponds to the saturation correction amount Gc in the above equation (1). FIG. 4B shows the characteristic of the correction coefficient (Fc) with respect to the input color difference (cb or cr). However, since the above equation (1) indicates saturation correction without considering dimming, actually, it is necessary to add the saturation correction enhancement ΔGc accompanying dimming to the saturation correction amount Gc. There is. ΔGc can be obtained by solving an equation under the condition that the average saturation is equal before and after dimming.

Further, when the light reduction amount is determined based on only the luminance, the light reduction is excessive and the vividness of red (R) or blue (B) may be impaired. That is, since dark images are less affected by dimming, it is a general rule that the amount of light dimming increases. However, even if the image is dark, for example, if there is a large and bright rose flower in the center of the screen, it is reasonable to impose a limit on the amount of light that can be reduced to reduce the saturation of the rose. is there. However, since red (R) and blue (B) have a low contribution rate to luminance (Y), if they are judged only by luminance (Y), the illumination is excessively reduced based on the judgment that they are dark images. I will let you. Therefore, in order to prevent such excessive dimming, as well as luminance (Y), chrominance (red color difference (Cr), and blue color difference (Cb)) is also configured to determine a dimming basis, a luminance When the color difference satisfies a predetermined relationship, the saturation is prioritized to limit the amount of light reduction. As a result, dimming is suppressed in an image with high saturation, and reduction in saturation of the display image is suppressed.

FIG. 4C is a diagram for describing processing for determining which of dimming or saturation preservation is to be prioritized using a threshold value determined by the relationship between average luminance and average color difference . As shown in the figure, a threshold value determined by the relationship between the average value of luminance and the average value of color difference is set, and dimming is performed based on luminance, or dimming is performed based on color difference , with the threshold as a boundary. Judge whether to do.

In the drawing, a hatched area ZP2 is a dimming area based on the color difference (cr, cb), and ZP1 is a dimming area based on the luminance (Y). For example, when the average luminance value is “64”, the image is dark, and therefore the amount of light reduction is considerably increased if only the luminance is determined. However, if the average color difference is, for example, “96”, it is an image with a high color difference , so that it is necessary to suppress a decrease in saturation due to light reduction. Therefore, in such a case, the amount of light reduction is determined based on the color difference (the amount of light reduction is made smaller than when the luminance is used as a reference). In other words, a predetermined restriction due to the color difference is provided for the amount of light reduced based on the luminance, thereby suppressing excessive light reduction that causes an extreme decrease in saturation.

  (Filter processing to prevent flicker associated with scene changes)

  When adaptive illumination dimming and image correction are performed on each frame of a moving image, visual flicker occurs due to a rapid change in the illumination luminance and the image correction amount accompanying a scene change. Therefore, filter processing suitable for each characteristic is executed for both illumination correction and image correction obtained in units of frames. Since the change in illumination brightness is a change between white and black, which is easy to recognize visually, filter processing with a long time constant is applied.On the other hand, the change in image correction amount is a halftone change that is not noticeable. A filter process with a short time constant is applied with emphasis on quick response to scene changes. As a result, it is possible to effectively suppress flicker associated with adaptive illumination correction while realizing image correction following a scene change of a moving image.

  In addition, if each filter process is executed independently, the balance between the illumination correction and the image correction may be lost and the image quality may deteriorate. Therefore, the first filter processing is performed on the illumination luminance obtained in frame units, the image correction amount is obtained from the result, and the second filter processing is performed on the image correction amount (execution of serial processing is performed). Adopting a configuration to do). Since the amount of image correction adapted to the reduced light amount is calculated after the reduced amount of illumination luminance is calculated, the balance between the first and second filter processes is always ensured.

  FIG. 5 is a diagram for explaining the outline of the image display control device of the present invention and the contents of the filter processing. FIG. 5A is a block diagram showing the overall configuration of the image display control device, and FIG. FIG. 5A is a block diagram showing more specifically the configuration shown in FIG. 5A, and FIG. 5C is a diagram showing a time constant of filter processing executed at the time of dimming control. D) is a diagram showing a time constant of filter processing executed at the time of image correction.

As shown in FIG. 5 (A), luminance (Y), blue color difference (Cb), the maximum value among the average values of the red color difference (Cr) (written down and Wave) is input, the input signal Is subjected to linear processing (C) to calculate backlight luminance (K), and the backlight luminance (K) is filtered by the time axis filter 22 having a long time constant to obtain the final backlight luminance. (Dimming coefficient indicating backlight luminance after dimming) Kflt is obtained. Time axis filter 2
The characteristic of 2 is controlled by the filter coefficient P. The relationship between the value of the filter coefficient P and the change rate (ΔYave) of the average luminance of the image is as shown in FIG.

Based on the final backlight luminance (Kflt), the image correction amount calculation unit 24 calculates a correction amount Gm for brightness correction and saturation correction. The image correction amount Gym is subjected to a filtering process by the time axis filter 26 having a short time constant, whereby the final image correction amount (Gy ′) is obtained. The characteristics of the time axis filter 26 are controlled by the filter coefficient q. The relationship between the value of the filter coefficient q and the average luminance change rate (ΔYave) is as shown in FIG.

  As shown in FIG. 5B, the backlight time axis filter 22 is a recursive (IIR) filter, and the image correction amount time axis filter 26 is also a recursive (IIR) filter. is there. The transfer function of the time axis filter 22 for backlight is Hbl [z], and the transfer function of the time axis filter 26 for image correction amount is Himg [Z]. Therefore, the transfer function of the filter processing in the image display control apparatus is represented by Hbl [z] · Himg [Z]. The image correction calculation unit 24 is realized by a non-linear transfer function. In FIG. 5B, reference numerals 28 and 30 indicate delay elements.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
(Mounting mode of image display control device)
6 (A) to 6 (D) are block diagrams for explaining the mounting mode of the image display device of the present invention.

  In FIG. 6A, an image display control device (image display control LSI) is mounted on a mobile phone terminal (an example of an electronic device) 100. The cellular phone terminal 100 includes an antenna AN, a communication / image processing unit 102, a CCD camera 104, a host computer 106, an image display control device (image display control LSI) 108, and a driver 110 (panel driver 112 and back). A display panel (for example, a liquid crystal panel (LCD)) 116, and a backlight (LED) 118.

  In FIG. 6B, an image display control device (image display control LSI) 108 is mounted on the drive device (driver) 110 itself, and the image display control device (image display control LSI) 108 receives an image from the host computer 106. Signals and control information are input.

  In FIG. 6C, the image display control device (image display control LSI) 108 is mounted on the control device (controller) 130 of the driver 110. In FIG. 6D, an image display control device (image display control LSI) 108 is mounted on a drive control device 140 (integrated driver and controller) 140.

  The image display control device (image display control LSI) 108 according to the present invention has the characteristics that it can process a moving image such as a streaming image, can be processed in real time, has excellent power saving performance, and can be downsized. Therefore, by mounting the image display control device (image display control LSI) of the present invention, the drive device (driver) 110, the control device (controller) 130, and the drive control device (device in which the driver and the controller are integrated). In addition, the added value of the electronic device 100 is improved.

(Overall configuration of image display control device)
FIG. 7 is a block diagram showing an outline of the overall configuration of the image display control apparatus (image display control LSI) of the present invention.

Here, it is assumed that the image display control device 108 is mounted on a mobile terminal (including a mobile phone terminal, a PDA terminal, and a portable computer terminal). The portable terminal includes, for example, an antenna AN that receives one-segment broadcasting, a communication / image processing unit 102, and a host computer 106. For example, the host computer 106 supplies the received streaming video signal to the image display control device 108. Note that the image signal captured by the CCD camera can be supplied to the image display control device 108 (see FIG. 6A), but in FIG. 7, the CCD camera is omitted.

As shown in the figure, the image display control device 108 receives an image signal (RGB (color signal format) or YUV (luminance signal and color difference signal format)) given from the host computer 106, and the image signal is RGB. Is an image input interface (I / F) 150 for converting into a YUV image signal, a register 152 for temporarily storing control information given from the host computer 106, and a backlight luminance after dimming (dimming coefficient Kflt) And an image correction core 200 that performs an image correction process on the image signal so as to compensate for a decrease in image quality due to dimming, and a YUV format image signal is converted into an RGB format image signal, or the YUV format remains unchanged And an image output interface (I / F) 154 for outputting.

  The image correction core 200 extracts a synchronization signal from the YUV format image signal output from the image input interface (I / F) 150, generates a timing signal indicating the operation timing of each unit, and is necessary for calculation. A histogram creation unit (statistical information acquisition unit) 212 that acquires statistical information, a sequence counter 214, a code table 216 that stores microcode obtained by subdividing a correction algorithm, and an instruction and data by decoding the microcode. A decoder 217 to be generated, a common arithmetic unit 218 that is configured by a minimum circuit and used in common for each process of light control and image correction, and a correction coefficient for image correction generated by the operation are temporarily A coefficient buffer 220 that accumulates, an image correction unit 222 that corrects an image signal using a correction coefficient, A.

  FIG. 8 is a diagram showing the contents of control signals supplied from the host computer to the image display control device. For example, an image signal conforming to, for example, MPEG4 is input from the communication / image processing unit 102 to the host computer 106, and mode information (for example, a high-definition display mode is designated from the image input interface (I / F) 302). Mode signal) and image quality information (for example, information indicating gamma correction, contrast, intensity of saturation, scene weighting coefficient information, etc.) are input.

  An image signal (RGB format or YUV format) is output from the host computer 106, and gamma correction intensity (L1), contrast intensity (L2), saturation intensity (L3), and image correction scene weight as control information are output. The coefficient (L4), the backlight luminance reduction rate (power saving degree: L5), and the backlight scene weighting coefficient (L6) are output. The scene weighting factor for image correction (L4) and the scene weighting factor for backlight (L6) correspond to the filter coefficients P and Q in FIG.

  The control information described above is temporarily stored in the register 152 and then supplied to the shared arithmetic unit 218. The shared arithmetic unit 218 executes a predetermined operation using instructions and data from the decoder 217 based on the given control information, and performs a correction coefficient for image correction and a backlight luminance (a dimming coefficient Kflt). ) Is generated.

  FIG. 9 is a block diagram showing a specific configuration of the image display control apparatus shown in FIG. In FIG. 9, the configuration of the image correction core 200 is described more specifically. In FIG. 9, the same reference numerals are given to the portions common to FIG.

In FIG. 9, the shared arithmetic unit 218 includes first and second multiplexers (400a, 400b), an arithmetic logic unit (ALU) 402, a distributor 404 that distributes the arithmetic results of the arithmetic logic unit (ALU), A plurality of output destination registers (destination registers) 406. The output destination register 406 includes register groups 408a to 408c divided for each output destination. Further, a feedback path is formed that feeds back at least a part of the operation results accumulated in each of the plurality of register groups 408a to 408c to the input side of the first and second multiplexers (400a, 400b).

Hereinafter, the function and operation of each part of the image correction core 200 of FIG. 9 will be described in detail.
A histogram creation unit (statistical information acquisition unit) 212 acquires statistical information (statistical information about luminance and statistical information about color difference ) of image signals for one frame. A specific internal configuration of the histogram creation unit (statistical information acquisition unit) 212 will be described in the third embodiment.

  The code table (code storage unit) 216 stores a plurality of microcodes for designating the operation procedure of the shared arithmetic unit 218. The procedure for creating the code table 216 will be described in the second embodiment.

  The sequence counter (sequence instruction unit) 214 points to the code table 216 and controls the output order of the microcode from the code table 216. The decoder 217 sequentially decodes the output microcode from the code table 216 to generate at least one of an instruction and data (such as a coefficient) to be supplied to the shared arithmetic unit.

  The decoder 217 supplies the coefficients used for the operation to the first and second multiplexers (400a, 400b), and supplies the arithmetic instruction (opcode) to the arithmetic logic unit (ALU) 402 for distribution. Distribution destination information (destination information) is supplied to the device 404.

The shared computing unit 218 calculates the correction coefficient for image correction and the backlight luminance after dimming (the dimming coefficient Kflt) in real time. As a result, the digital signal processing described with reference to FIGS. 5A to 5D is executed by the calculation of the shared arithmetic unit 218. Also, the saturation enhancement process, the process of limiting the backlight luminance reduction rate to prevent the deterioration of the image quality of the high saturation image, and the first and second cycles described with reference to FIGS. Substantially all the processes for performing the type filter processing in series are executed.

  As described above, the operation of the shared arithmetic unit 218 is controlled by the microcode that encodes the signal processing procedure. By using a shared arithmetic unit having a minimum circuit configuration, real-time arithmetic can be performed without the need to provide the same type of hardware in parallel. Therefore, high-speed light control and image correction can be realized with the minimum circuit and the minimum power consumption.

The calculation result of the shared arithmetic unit 218 is temporarily stored in the register groups 408a to 408c divided for each output destination. The calculated backlight luminance (dimming coefficient Kflt) is output to the backlight (LED) driver, and the correction coefficient is stored in the coefficient buffer 410. The correction coefficients stored in the coefficient buffer 410 are supplied to the image correction unit 222 in synchronization with the input of the image signal of the next frame, and image correction (enhancement of luminance and saturation) is executed.

  In addition, at least a part of the operation result stored in each of the plurality of register groups 408a to 408c is fed back to the input side of the first and second multiplexers (400a, 400b) via the feedback path. As a result, first, the illumination brightness after dimming is obtained, the calculation result is returned to the input side, and a process for obtaining an image correction coefficient based on the obtained illumination brightness is executed. Further, the first and second cyclic (IIR) filter processes described above are executed.

Next, a procedure for creating the code table shown in FIG. 9 will be described. FIG. 10 is a diagram showing a procedure for creating a code table.

  In FIG. 10, first, a programming language for correcting an image signal so that a backlight for displaying an image is adaptively dimmed according to a display image and image quality deterioration due to dimming of the backlight is compensated. For example, an algorithm (enhancement operation algorithm) using a high-level programming language is prepared (step S500).

  Next, the algorithm created in the programming language is batch converted to generate microcode (step S502).

  Next, the generated microcode is written in a ROM (read only memory) (step S502).

In this way, the code table 216 can be created efficiently. In addition, by changing the algorithm (microcode), it is possible to relatively easily change the calculation contents of the shared arithmetic unit 218. Therefore, it is possible to flexibly cope with design changes.
Next, an example of a specific configuration inside the histogram creation unit (statistical information acquisition unit) 212 illustrated in FIG. 9 will be described.

As described above, the image display control device according to the present invention acquires statistical values related to luminance and color difference of an image signal for one frame, and adapts backlight luminance and image signals ( color difference and luminance) based on the statistical values. To correct. Further, as described above, when correcting an image, if the average color difference is high even if the average luminance is low, correction is performed to limit the backlight dimming rate by giving priority to the color difference over power saving. Done. In order to execute such control, it is necessary to acquire necessary luminance and color difference statistical value information at high speed.

  FIG. 11 is a circuit diagram showing a specific internal configuration of the histogram creation unit (statistical information acquisition unit) in FIG. 9. As shown in the drawing, a plurality of statistical units (EX0 to EX255) for creating a luminance histogram are provided. All of EX0 to EX255 have the same circuit configuration.

  That is, each of the plurality of statistical units (EX0 to EX255) for creating the luminance histogram is a comparison that compares the luminance value of the input image signal with the reference luminance value (this reference luminance value is different for each statistical unit). A counter 1, an up counter 2, an AND gate 3, and a statistical value buffer 4. The luminance value is 256 gradations, and each of the reference luminance values (1) to (255) corresponding to each gradation is given to each of the comparators (EX0 to EX255).

  The luminance signal (Y) of the image signal is input in parallel to each statistical unit (EX0 to EX255), and is compared simultaneously with the reference luminance values (1) to (255) corresponding to each gradation by each comparator 1. . Each comparator 1 functions as a luminance value coincidence detection circuit, and when the input luminance value coincides with the reference luminance value, the output of the comparator becomes high level, thereby supplying the other input terminal of the AND gate 3. The operation clock is supplied to the statistical value buffer 4.

  The statistical value buffer 4 captures and temporarily holds the count value of the up counter 2 at the timing when the clock is supplied (that is, the statistical value buffer 4 functions as a register). In this way, the luminance value of each pixel included in the image signal is classified and counted for each gradation value. Since the luminance value of the input image is input in parallel to each statistical unit and the counting operation is simultaneously performed in each statistical unit, it is possible to obtain an extremely high-speed statistical value.

  The luminance maximum value / minimum value detector 5 obtains the maximum value and the minimum value of the luminance (Y) based on the count value of each statistical unit (EX0 to EX255). In addition, the standard deviation calculation unit 6 calculates a standard deviation value indicating the distribution of luminance (Y). It is possible to estimate (specify) the luminance distribution of an image of one frame based on the maximum value / minimum value / standard deviation value of luminance (Y). Using the statistical values calculated in this way, adaptive light control and image correction are executed.

Further, as shown in the lower side of FIG. 11, the statistical information acquisition unit 212, further, a statistical unit ES (Y) for obtaining an average value of the luminance (Y), the average value of the blue color difference (Cb) a statistical unit ES (Cb) for determining, statistical unit ES for determining the average value of the red color difference (Cr) (Cr) is provided. As described above, the average be the average luminance of the image is low chrominance (especially, the average value of the contribution is less blue color difference and red color difference to brightness) when is high, suppressing the extinction ratio in favor of saving color difference In order to carry out such advanced dimming control, it is necessary to compare the average values of luminance and color difference. Therefore, the statistical units ES (Y), ES (Cb), ES (Cr) Are provided so that average values of luminance and color difference can also be obtained at high speed.

Each statistical unit (ES (Y), ES (Cb), ES (Cr)) has the same configuration. That is, each statistical unit (ES (Y), ES (Cb), ES (Cr)) includes an adder (7a-7c) for accumulating the values of Y, Cb, Cr, and a sum for accumulating the accumulated addition value. Value buffers (8a to 8c). The average value calculators (9a to 9c) calculate and output an average value of luminance (Y), an average value of color difference (Cb), and an average value of color difference (Cr), respectively.

As described in FIG. 4 (C), the by the relation of the color difference and luminance (Y) (Cb, Cr) , a base for any dimming coefficient calculating luminance (Y) or color difference (Cb, Cr) It is selected whether to do. The average value of luminance (Y), the average value of color difference (Cb), and the average value of color difference (Cr) are used for such a determination.

In this way, by inputting image signals in parallel to each statistical unit and simultaneously updating the luminance count value in each statistical unit, the luminance count value can be acquired at an extremely high speed. Further, by acquiring not only the luminance statistical information but also the color difference statistical information, adaptive image correction based on the color difference is also possible. Further, since the statistical unit and the total value unit are compact circuits and have the same configuration, an effect that a high-density circuit layout can be realized is also obtained.

  Also, the AND gate A1 shown in the lower left of FIG. 11 is intended to gate the operation clock given to each statistical unit (EX0 to EX255) with a statistical value valid signal and stop the clock supply as necessary. Is provided. Similarly, the AND gate A2 gates the operation clock given to each statistical unit (ES (Y), ES (Cb), ES (Cr)) with the average valid signal, and stops the clock supply as necessary. It is provided for the purpose of doing. When statistical value acquisition is unnecessary, power supply can be reduced by stopping clock supply and statistical value acquisition operation. This point will be described more specifically with reference to FIG.

  FIG. 12 is a block diagram showing a configuration for stopping the statistical value counting operation in the histogram creation unit (statistical information acquisition unit) when the statistical value acquisition operation is unnecessary in order to further reduce power consumption. . Note that, in FIG. 12, the same reference numerals are given to portions common to the above-described drawings.

As described in FIG. 11, the histogram creation unit (statistical information acquisition unit) 212 includes AND gates A1 and A2 for gating the operation clock (CLK). FIG.
, The operation clock (CLK) is supplied from the timing unit 210. Note that the timing unit 210 generates an operation clock (CLK) by separating a synchronous clock included in an image signal input to the image input interface (I / F).

  The AND gate A1 gates the operation clock given to each statistical unit (EX0 to EX255) by a statistical value valid signal (first enable signal). Similarly, the AND gate A2 includes each statistical unit (ES (Y ), ES (Cb), ES (Cr)) are gated by an average effective signal (second enable signal).

  The statistical value valid signal and the average valid signal are output from, for example, a luminance change detector 107 provided in the host computer 106. The luminance change detector 107 determines whether or not there is a change in the image between successive frames based on the motion vector sent from the codec included in the communication / image processing unit 102.

  Further, the luminance change detector 107 can also know that there is no change in the image based on the status notification signal sent from the communication / image processing unit 102. For example, when the status notification signal indicates a pause (stop motion) mode, it can be determined that the playback of the moving image is temporarily stopped and there is no change in the image between frames.

  The luminance change detector 107 can also directly monitor the image data in the frame memory 105 and detect the presence or absence of an image change.

  If the luminance change detector 107 determines that there is no image change between consecutive frames, it is unnecessary to create a new statistical value. Therefore, the statistical value effective signal and the average effective signal are set to low level, and AND is performed. Output of operation clocks Q1 and Q2 from gates A1 and A2 is prohibited. As a result, each statistical unit (EX0 to EX255, and ES (Y), ES (Cb), ES (Cr)) stops counting. Therefore, power consumption can be further reduced.

  In this way, the units that perform the count operation have the same type of configuration and operate with a common operation clock, so the operation clock is gated and the supply of the operation clock is stopped. Thus, the counting operation can be stopped all at once. Therefore, useless power consumption can be effectively reduced. In addition, the circuit configuration is simple and easy to implement.

(Second Embodiment)
When performing adaptive image correction, the statistical value of the previous frame is acquired, the correction coefficient is calculated using the acquired statistical value, and the image of the next frame is corrected using the correction coefficient. Since this is a procedure, it is necessary to wait for the correction process for the image of the next frame after the input of the image for one frame is completed until the correction coefficient is calculated. That is, the image correction of the moving image is delayed for the time required for calculating the correction coefficient. In order to prevent such a delay from occurring, in the present embodiment, the following configuration is further adopted in addition to the configuration of the above-described embodiment.

(Configuration to enable real-time processing)
Hereinafter, a configuration for enabling real-time processing will be described with reference to FIGS.

FIG. 13 is a block diagram showing a main configuration around the histogram creation unit (statistical information acquisition unit). As shown in FIG. 13, the histogram creation unit (statistical information acquisition unit) 212 is given control information from the host computer 106 and also includes a timing unit 210.
Based on the timing information from, the creation of a luminance histogram and the like and the output of statistical value information to the calculator are performed (however, the timing unit 210 is not essential, and the histogram creating unit (statistical information obtaining unit)) 212 itself may generate the timing signal autonomously).

  Here, real-time processing can be performed by controlling the end timing of the statistical value acquisition of the histogram creation unit (statistical information acquisition unit) 212.

  That is, when the histogram creation unit (statistical information acquisition unit) 212 acquires statistical information of an image for one frame, the statistical value acquisition process is terminated without waiting for acquisition of statistical values of all images for one frame. Then, it becomes possible to calculate the correction coefficient based on the acquired statistical value within the remaining time until the end of one frame.

  Even if a part of the image of the frame (for example, an image of the peripheral part) is excluded from the acquisition target of the statistical information, the accuracy of the obtained statistical value is not greatly affected, and the accuracy of the statistical value can be ensured.

  FIG. 14 is a diagram illustrating an example of timing control in a histogram creation unit (statistical information acquisition unit) for enabling real-time image correction based on statistical values. As shown in the lower side of FIG. 13, an effective evaluation pixel area Z1 is set for an image of one frame, and the remaining area is an invalid area Z2. The pixels for which the statistical values are acquired are only the pixels included in the effective evaluation pixel area Z1, and the pixels included in the invalid area Z2 are not a basis for generating the statistical values.

  As illustrated, in the present embodiment, the last line of one frame is set as an invalid area Z2. Although it is not limited to this, since it is desirable to obtain statistical values for as many images as possible, only the last line is excluded from the statistical value acquisition targets. Further, by adopting a configuration using a microprogram-controlled arithmetic circuit without using an LUT (the configuration shown in FIGS. 7 and 9), an extremely high-speed operation can be realized. It is possible to obtain the illumination brightness and the correction coefficient after dimming.

In FIG. 14, times t1 and t10 indicate the timing of the vertical synchronization signal (Vsync) of the input image signal. From time t2 to time t8, acquisition of statistical values for the effective evaluation pixel region Z1 (that is, using the configuration of FIG. 11, statistical value count, luminance maximum value / minimum value, standard deviation value, luminance average value, blue color difference (Cb) average, the acquisition of the red color difference (Cr) average) is performed.

  Then, at time t8, the statistical value acquisition process ends. Next, at a time corresponding to the last one row (final row) that is an invalid area (time t8 to t9), for example, the shared arithmetic unit 218 in FIG. The backlight luminance (dimming coefficient Kfit) and the correction coefficient are calculated.

When the next frame is started at time t10, the image correction unit 222 in FIG. 9 corrects the image signal using the calculated correction coefficient. That is, image correction that enhances luminance and color difference is executed in accordance with the degree of dimming.

  As described above, since the acquisition of the statistical value and the calculation of the correction coefficient are completed during the period corresponding to one frame, even when the next frame is input without delay, the image correction can be started immediately. Real-time correction of moving images is realized.

  In the above description, the statistical value is acquired from the immediately preceding frame, but the statistical value may be acquired based on both the immediately preceding frame and the past frame.

  The operations described above are summarized as shown in FIG. In FIG. 15, the statistical value acquisition process is ended in the middle of one frame period, the correction coefficient and the dimming coefficient are calculated until the end of one frame period, and the image of the next frame is corrected by the calculated correction coefficient. It is a flowchart which shows the specific process sequence of a process.

  The processing of FIG. 15 is assumed to be realized using the configuration of FIG. As shown in the figure, first, necessary coefficients (standard deviation value threshold, maximum value minimum value threshold, etc. necessary for statistical value calculation) are set by the host computer (step ST700).

Next, an image signal (video signal) is input (step ST701). Next, based on the image data for one frame excluding the last row, a histogram (basic data for calculating statistical values) indicating the luminance distribution of the image signal, the accumulated luminance value, and the accumulated color difference value is created. . (Step ST702). Next, the coefficient (statistical value) which shows the characteristic of a statistics is calculated | required from the produced histogram (step ST703). Next, the obtained statistical value is supplied to computing unit 218 in FIG. 9, and a correction coefficient and backlight luminance (dimming coefficient) are calculated based on the statistical value (step ST704).

  The process of ST704 ends within one frame period. Then, the input of the image signal of the next frame is started, and the image signal is subjected to real-time image correction using the correction coefficient. In parallel with this, the backlight luminance (dimming coefficient) is changed to LED. At the same time, generation of a new histogram is started (step ST705).

  As described above, by adopting the configuration of the present embodiment, it is possible to realize adaptive video image correction based on statistical values without causing any delay time.

  As described above, the present invention has been described using the embodiments. However, the present invention is not limited thereto, and various modifications and applications are possible without departing from the gist of the present invention. If a high-speed correction coefficient can be calculated, a lookup table type arithmetic circuit may be used instead of the arithmetic unit. That is, in this specification, the “calculator” includes other arithmetic means in addition to the microprogram-controlled arithmetic unit described in the above embodiment.

As described above, according to at least one embodiment of the present invention, for example, the following effects can be obtained. However, the following effects are not always obtained, and the following list of effects should not be used as a basis for unduly limiting the present invention.
By inputting an image signal in parallel to each of the statistical units and simultaneously updating the luminance count value in each statistical unit, the luminance count value can be acquired at a very high speed.

Further, by acquiring not only the luminance statistical information but also the color difference statistical information, adaptive image correction based on the color difference becomes possible.

  Further, since the statistical unit and the total value unit are compact circuits and have the same configuration, a high-density circuit layout can be realized.

In addition, when it is not necessary to acquire statistical information, wasteful power consumption can be eliminated by stopping the counting operation of the statistical unit and the total value unit. Since the statistical value unit and the total value unit have the same configuration that operates with a common operating clock, for example, by stopping the common operating clock by gating, the counting operation can be performed simultaneously and easily. Can be stopped.

  In addition, the technique of the present invention is used for image display control in the case of performing adaptive dimming of a backlight for power saving and adaptive image correction for preventing image quality deterioration accompanying the dimming at the same time. By applying the above, it is possible to realize advanced calculations based on statistical values in low power consumption and in real time.

  In addition, by using an arithmetic unit of the microprogram control system, real-time computation is possible without providing the same type of hardware in parallel, and high-speed adaptive dimming control and adaptive image correction are achieved with the minimum circuit and minimum power consumption. Can be realized.

  In addition, by performing adaptive dimming processing and image correction simultaneously, power consumption can be significantly reduced by adaptive dimming of illumination brightness while minimizing degradation in image quality (a reduction of up to 30%). Confirmed). Further, since it can be realized with a minimum amount of hardware, space can be saved. Further, even in the processing of moving images such as streaming video, no delay time occurs, and real-time and highly accurate processing is realized.

  Further, according to the present invention, it is possible to realize high added value of a drive device (driver) such as a liquid crystal display device, a control device (controller), and a drive control device (device in which a driver and a controller are integrated).

  Further, by mounting the image display control device (LSI) of the present invention on a mobile terminal (including a mobile phone terminal, a PDA terminal, and a portable computer), it is possible to display a streaming image such as one-segment broadcasting with high image quality. And a longer battery life can be realized.

  Further, according to the present invention, real-time video image correction based on statistical values is realized, and adaptive dimming of lighting for power saving and adaptation for preventing image quality deterioration due to the dimming are realized. Even when simultaneous image correction is performed simultaneously, real-time performance, circuit scale reduction, and low power consumption can be realized.

  In addition, according to the present invention, it is possible to provide a technique for acquiring moving image statistical information at high speed and with low power consumption.

  In addition, according to the present invention, various statistical information of moving images can be acquired at high speed and efficiently while preventing the circuit configuration from becoming complicated, and further, calculations using statistical information can be executed at high speed and efficiency. Thus, for example, while achieving low power consumption and suppression of increase in circuit scale, it is unprecedentedly high to compensate for adaptive light reduction of light and deterioration of image quality due to the light reduction. Accurate image correction can be realized at the same time.

  INDUSTRIAL APPLICABILITY The present invention is useful as a technique for acquiring various statistical information of moving images at an extremely high speed, and can be widely used for image correction, dimming control, and the like. The present invention is effective when adaptively correcting a moving image in real time, and is suitable as an image display control device or the like that supports streaming reproduction, for example. In addition, the present invention adaptively reduces the luminance of the display illumination in accordance with the display image, and corrects the image signal so as to compensate for the deterioration in image quality due to the reduction. It is useful as an image display control LSI). The present invention also relates to electronic devices such as portable terminals such as display panel drive devices (drivers), display panel control devices (controllers), display panel drive control devices (devices in which a driver and a controller are integrated), and the like. Is also useful.

1A to 1C are diagrams for explaining the contents of adaptive dimming control and image correction according to a display image employed in the image display control apparatus (image display control LSI) of the present invention. FIG. Backlight reduction rate, image correction amount (Gy) without dimming, image correction amount (Gy ′) with dimming, and image correction accompanying dimming with respect to average luminance (Yave) of an image of one frame It is a characteristic view which shows the change of quantity reinforcement | strengthening ((DELTA) Gy). It is a figure which shows how the characteristic line of the image correction amount reinforcement | strength ((DELTA) Gy = Gy'-Gy) accompanying light control changes according to the luminance reduction rate of a backlight. 4A to 4C are diagrams for explaining saturation correction. FIG. 5 is a diagram for explaining the outline of the image display control device of the present invention and the contents of filter processing, FIG. 5A is a block diagram showing the overall configuration of the image display control device, and FIG. 5A is a block diagram showing more specifically the configuration shown in FIG. 5A, and FIG. 5C is a diagram showing a time constant of filter processing executed at the time of dimming control, and FIG. FIG. 4 is a diagram showing a time constant of filter processing executed at the time of image correction. 6 (A) to 6 (D) are block diagrams for explaining the mounting mode of the image display device of the present invention. It is a block diagram which shows the outline | summary of the whole structure of the image display control apparatus (image display control LSI) of this invention. It is a figure which shows the content of the control signal which a host computer supplies to an image display control apparatus. It is a block diagram which shows the specific structure of the image display control apparatus shown by FIG. It is a figure which shows the preparation procedure of a code table. FIG. 10 is a circuit diagram illustrating an example of a specific configuration inside the histogram creation unit (statistical information acquisition unit) illustrated in FIG. 9. It is a block diagram which shows the structure for stopping the count operation | movement of the statistical value in a histogram preparation part (statistical information acquisition part), when a statistical value acquisition operation | movement is unnecessary in order to further reduce power consumption. It is a block diagram which extracts and shows the main structures around a histogram creation part (statistical information acquisition part). It is a figure which shows an example of the timing control in a histogram preparation part (statistical information acquisition part) for enabling the real-time image correction based on a statistical value. Specifically, the statistical value acquisition process is ended in the middle of one frame period, the correction coefficient and the dimming coefficient are calculated until the end of the one frame period, and the image of the next frame is corrected by the calculated correction coefficient. It is a flowchart which shows a typical process sequence.

1 comparator, 2 up counter (incrementer), 3 AND gate,
4 Statistical value buffer, 5 Luminance maximum / minimum value detector 6 Standard deviation calculator,
7a to 7c Adder 8a to 8c Total value buffer, 100 Mobile phone terminal (electronic device), 102 Communication / image processing unit, 104 CCD camera, 106 Host computer, 108 Image display control device, 110 driver, 112 Panel driver, 114 Backlight driver, 116 display panel, 118 backlight (LED), 150 image input interface (I / F), 152 register for storing control information from the host computer, 154 image output interface (I / F), 200 image correction Core, 210 Timing unit, 212 Histogram creation unit (statistical information acquisition unit), 214 Sequence counter, 216 code table, 217 decoder, 218 shared arithmetic unit, 220 coefficient buffer, 222 Image correction unit, 400a, 400b, first and second Second multiplexer, 402 arithmetic logic unit (ALU), 404 distributor, 406 distribution destination register, 408a to 408c, a group of registers distinguished for each distribution destination, 410 coefficient buffer, EX0 to EX255 statistics unit, ES (Y) Luminance total value unit,
ES (Cb) blue color difference total value unit, ES (Cr) red color difference total value unit

Claims (15)

An image display control device that corrects an image signal based on statistical information,
As the statistical information , a statistical information acquisition unit that acquires statistical information of luminance, blue difference, and red difference of the image signal for each frame;
An arithmetic unit that generates a correction coefficient used for correcting an image signal using the statistical information about the previous frame output from the statistical information acquisition unit;
An image correction unit that corrects the image signal using the correction coefficient;
Have
The statistical information acquisition unit
A plurality of statistical units comprising: a comparator that compares the luminance of the image signal with a reference luminance and outputs a comparison result; and a statistical value buffer that updates a count value in accordance with the comparison result;
A statistical value calculation unit that calculates a predetermined statistical value based on a count value of the statistical value buffer that is output from each of the plurality of statistical units;
The reference brightness in each of the plurality of statistical units is set to a value different from each other, and the image signal is input in parallel to each of the plurality of statistical units ,
The statistical value calculation unit includes a luminance maximum value / minimum value detection unit that detects a maximum value and a minimum value of luminance of an image signal, and a standard deviation calculation unit that obtains a standard deviation value,
Wherein the arithmetic unit, the luminance maximum value was obtained by calculation, the image display control device that each of the minimum luminance value and the standard deviation value, characterized in Rukoto supplied. The image display control device according to claim 1 ,
The statistical information acquisition unit, the luminance, as a configuration for acquiring the respective statistics of the blue color difference and the red color difference,
A luminance total value unit including an adder for accumulating the luminance of each pixel, and a luminance total value buffer for accumulating the accumulated addition value;
An adder for cumulatively adding the blue color difference of each pixel, and blue color difference sum unit including a blue color difference sum buffer for storing the accumulated value, a,
An adder for cumulatively adding the red color difference of each pixel, and red chrominance sum unit including a red color difference sum buffer for storing the accumulated value, a,
The total luminance values determined, and the average calculating unit for calculating, based on the blue color difference sum value and the red color difference sum value, the luminance average value of each of the blue color difference average value and the red color difference average value,
An image display control device comprising: The image display control device according to claim 1 or 2 ,
An image display control apparatus, wherein when the acquisition of statistical information is unnecessary, the operation for acquiring statistical information in the statistical information acquisition unit is stopped. The image display control device according to any one of claims 1 to 3 ,
An image display control apparatus, wherein when the acquisition of statistical information is unnecessary, the counting operation of the statistical value buffer included in each of the plurality of statistical units is stopped. The image display control device according to claim 4 ,
A gate circuit for controlling supply / non-supply of the operation clock to each of the statistical value buffers is provided, and output / non-output of the operation clock from the gate circuit is switched by a first enable signal. A featured image display control device. The image display control device according to claim 2 ,
If the acquisition of statistical information is unnecessary, stop the counting operation of the statistical value buffer included in each of the plurality of statistical units; and
Image display control apparatus characterized by stopping the brightness total value buffer, the blue color difference sum value buffer and the count operation of the red color difference sum buffer. The image display control device according to claim 6 ,
The luminance total value buffer, a gate circuit for supplying an operation clock to each of the blue color difference sum buffer and the red color difference sum buffer is provided, the operation clock output / non-output from the gate circuit, the 2. An image display control device that is switched by an enable signal of 2. The image display control device according to claim 1 ,
The computing unit also calculates the illumination brightness after dimming when dimming control is performed that adaptively dims the illumination for image display according to the image signal, using the statistical information of the previous frame. And an image display control device for generating the correction coefficient used for correcting the image signal to compensate for a decrease in image quality due to dimming of the illumination. The image display control device according to claim 8 , further comprising:
A code storage unit storing a plurality of codes for designating the operation procedure of the computing unit;
A sequence instruction unit for controlling the output order of the codes from the code storage unit;
A decoder that decodes the code output from the code storage unit and generates at least one of an instruction and data to be supplied to the computing unit;
An image display control device comprising: The image display control device according to claim 9 ,
The arithmetic unit includes first and second multiplexers, and arithmetic logic unit, and a distributor which distributes an operation result of said arithmetic logic unit includes,
From the decoder, the coefficients for the first and second multiplexer used in the calculation as the data, the operation instruction as the instruction to the arithmetic logic unit, wherein for the distributor sorting information as data, image display control device, wherein each supplied. The image display control device according to claim 10 ,
The computing unit further includes:
Multiple output destination registers,
A feedback path for returning at least a part of the signals accumulated in the plurality of output destination registers to the input side;
An image display control device comprising: Driving device for an electro-optical device equipped with the image display control device according to any one of claims 1 to 11. A control device for an electro-optical device on which the image display control device according to any one of claims 1 to 11 is mounted. Drive control device of an electro-optical device equipped with the image display control device according to any one of claims 1 to 11. Electronic apparatus including the image display control device according to any one of claims 1 to 11.

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