CN211267005U - Digital film projection system - Google Patents

Abstract

The utility model discloses a digital film projection system, including at least one low dynamic range projecting apparatus and at least one high dynamic range projecting apparatus, wherein the system receives the digital film package and sends first image data and second image data to low dynamic range projecting apparatus and high dynamic range projecting apparatus respectively, the light that low dynamic range projecting apparatus and the high dynamic range projecting apparatus cast is made up into the projection image that is used for watching; a modulation power supply for modulating the brightness of the projected light of the low dynamic range projector in accordance with a control signal. The embodiment of the utility model discloses an adopt the light-emitting luminance of circuit form regulation projecting apparatus, only need the circuit board just can realize, simple structure does not have light loss, and the light efficiency is high. Further, by the preferred embodiments of the present invention, the inter-frame contrast and/or intra-frame contrast can be improved.

Description

Digital film projection system

Technical Field

The utility model relates to a film projection technical field. And more particularly to a digital cinema projection system.

Background

Chinese patent application publication No. CN106537899A entitled "driving scheme optimized for multi-projector system" discloses a projection system. Fig. 1 schematically illustrates a projector system including a plurality of projectors. All of the plurality of projectors contribute light to the same viewing area (e.g., the boundaries of the projectors' fields of view may be the same). Each projector of the plurality of projectors may transmit light to any portion of the viewing area. The viewer perceives the combined output of the projectors. In a system combining low dynamic range projectors and high dynamic range projectors (LDR and HDR), the optimal ratio of light contributed to the final image by each of the projectors can vary widely.

However, the projection system uses the aperture structure, so that the light incident from the low dynamic range projector has large light-emitting loss and low light efficiency, and a driving mechanism for driving the aperture to change the aperture is also required due to the presence of the aperture, which inevitably makes the light path system engineering difficult to implement.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a digital cinema projection system to solve at least one in the problem that prior art exists.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a digital cinema projection system comprising:

at least one low dynamic range projector and at least one high dynamic range projector, wherein the system receives a digital cinema package and sends first image data and second image data to the low dynamic range projector and the high dynamic range projector, respectively, the light projected by the low dynamic range projector and the high dynamic range projector being combined into a projected image for viewing;

a modulation power supply for modulating the brightness of the projected light of the low dynamic range projector in accordance with a control signal.

In an alternative embodiment, the control signal is related to a desired maximum output luminance for each frame of the original image in the digital cinema package, where the desired maximum output luminance is the maximum luminance value of the pixels in the frame/the maximum luminance values of the pixels in all frames of the original image x the maximum output luminance of the low dynamic range projector.

In an alternative embodiment, the luminance value of each pixel in each frame of the first image data is equal to the luminance value of the corresponding pixel in the corresponding frame of the original image x the maximum luminance value of the pixels in all frames of the original image/the maximum luminance value of the pixels in the corresponding frame.

In an optional embodiment, the system further comprises

Control hardware configured to receive the digital cinema package; and is

Configured to generate the first image data and the second image data, to be sent to the low dynamic range projector and the high dynamic range projector, respectively; and is

Configured to generate the control signal and transmit the control signal to the modulated power supply.

In an optional embodiment, the system further comprises control hardware configured to receive the digital cinema package, wherein the digital cinema package contains the control signal sent to the modulated power supply; and configured to generate the first image data and the second image data for transmission to the low dynamic range projector and the high dynamic range projector, respectively, for projection.

In an alternative embodiment, the digital cinema package contains the first image data, the second image data and the control signal and the first image data, the second image data and the control signal are sent to the low dynamic range projector, the high dynamic range projector and the modulated power supply, respectively.

In an alternative embodiment of the method of the invention,

the modulation power supply is a pulse width modulator;

the control hardware is configured to:

acquiring the maximum brightness values of all pixels in all frame images in the original image in the digital film package, namely the standard maximum brightness values;

obtaining the maximum brightness value of a pixel in a frame or a set of consecutive frames from an image of the frame or a set of consecutive frames

Bmax, thereby obtaining the brightness ratio R of the brightest pixel_MB＝(B_maxStandard maximum brightness value) 100%;

calculating the maximum output luminance B required for said frame or successive frames_frame＝R_MBLB, wherein LB is Low

Maximum output brightness of the dynamic range projector;

according to the pulse duty ratio of the pulse power supply control signal and the output of the projector with the low dynamic range

Luminance mapping relation determination B_frameA corresponding pulse width duty cycle;

and outputting the control signal according to the duty ratio.

In an optional embodiment, the control hardware is further configured to:

converting the luminance value B of each pixel in the frame or successive frames to Bt ═ B/R_MB＝B standard maximum

High brightness value/B_maxThereby generating the first image data.

In an optional embodiment, the control hardware is a single chip microcomputer.

In an alternative embodiment, the control signal is encoded in the digital cinema package in-frame with the original images in the digital cinema package.

The utility model has the advantages as follows:

the embodiment of the utility model discloses an adopt the circuit form to modulate the power for example pulse width modulator promptly and adjust the light-emitting luminance of projecting apparatus, only need the circuit board just can realize, simple structure does not have light loss, and the light efficiency is high. Further, by the preferred embodiments of the present invention, the inter-frame contrast and/or intra-frame contrast can be improved.

Drawings

The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings;

fig. 1 shows a block diagram of a prior art projection system.

Fig. 2 illustrates a digital cinema presentation system according to one embodiment of the present invention.

Fig. 3 shows a luminance-duty ratio mapping diagram according to an embodiment of the present invention.

Fig. 4 shows a digital cinema projection system according to another embodiment of the present invention.

Fig. 5 shows a digital cinema projection system according to still another embodiment of the present invention.

The same or similar components in the drawings are denoted by the same or similar reference numerals.

Detailed Description

In order to explain the present invention more clearly, the present invention will be further described with reference to the preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

First embodiment-real-time analysis, real-time processing

Fig. 2 schematically illustrates a digital cinema projection system comprising one Low Dynamic Range (LDR) projector and one High Dynamic Range (HDR) projector. Those skilled in the art will appreciate that the inventive arrangements are not so limited and may include multiple LDR projectors and multiple HDR projectors.

In some implementations, all of the projectors in the plurality contribute light to the same viewing area (e.g., the boundaries of the projectors' fields of view may be the same). Each projector of the plurality of projectors may transmit light to any portion of the viewing area. The viewer perceives the combined output of the projectors. In some implementations, each of the projectors projects on the entire display area of the viewing screen.

In a system combining LDR and HDR projectors (LDR and HDR), the optimal ratio of light contributed by each of the projectors to the final image may vary widely. This change is the result of image and environmental attributes such as:

ambient light level at screen position

Peak brightness of the image

Average brightness of the image

Light output of two projectors

Efficiency of two projectors (lumen/watt)

Minimum black level for LDR projector

Amount of black in the image

Closeness of Black to Bright features (light curtain Lighting)

Presence of non-uniformities (or other artifacts) in an LDR projector that can be corrected by an HDR projector

The presence of speckle (or other artifacts) in an HDR projector that can be reduced by using an LDR projector

Ability to reduce power consumption of projectors by showing darker content (for power consumption optimization)

It is still exemplified that the digital cinema projection system 1 includes one LDR projector 10 and one HDR projector 12. The system receives a Digital Cinema Package (DCP). In this embodiment, the digital cinema package is a standard DCP package known in the art and may be stored in the cinema's image memory and decoded by an Integrated Media Block (IMB) and sent to the control hardware 16. In the present embodiment, the digital cinema exhibition system 1 includes control hardware 16 that receives the DCP packets and generates first image data and second image data, which are sent to an LDR projector 10 (i.e., "video to LDR" in fig. 2) and an HDR projector 12 (i.e., "video to HDR" in fig. 2), respectively, and the light projected by the LDR projector and the HDR projector is combined into a projected image for viewing.

The control hardware 16 may send the original image in the DCP to the LDR projector and the HDR projector for projection in the form of the first image data and the second image data, respectively. In another embodiment, the control hardware 16 may process the original image and send the processed original image to the LDR projector and the HDR projector for projection as the first image data and the second image data. For example, the original image is processed by the following step S17 to obtain a video to LDR. For another example, all regions of the original image other than the region where the peak luminance exceeds the upper limit of the LDR dynamic range are changed to black to form the second data image.

The digital cinema projection system 1 further comprises a modulation power supply 14, also referred to as a modulatable power supply, for modulating the brightness of the projected light of the LDR projector in accordance with control signals from the control hardware. Note that the modulation power supply described in this application means that the brightness of the projected light of the LDR projector is modulated in the form of a circuit instead of an optical path.

Optionally, the modulation power supply is a pulse width modulator, and the brightness of the light source in the LDR projector is modulated by changing a pulse width duty ratio. The pulse width modulator may include a power supply controller and a duty ratio changing unit. The power supply controller is used for receiving the control signal and instructing the duty ratio changing unit to change the duty ratio of the pulse signal. Pulse width modulation techniques are well known to those skilled in the art and will not be described in detail herein.

In another example, the modulated power supply may be implemented with the most common digital-to-analog converter. For example, digital signals are used to control the voltage or current of the LDR projector light source by outputting analog signals with different voltage/current values.

Compare in prior art's light ring scheme, the utility model discloses a circuit form is the light-emitting luminance of modulation power supply for example pulse width modulator regulation projecting apparatus promptly, only needs the circuit board just can realize, simple structure, does not have optical loss, and the light efficiency is high.

In order to be able to control the light output brightness more finely in dependence on the control signal, the control hardware 16 may generate and send the control signal to the modulation power supply 14 based on the correspondence between the control data, i.e. the control signal, for each specific projector and the LDR projector output brightness, e.g. by experiments in advance.

In an example where the modulation power source is a pulse width modulator, the control data is a mapping relationship between a pulse duty ratio of a pulse control signal and pixel brightness of the projected image.

Further, in the example of pulse width modulation, for example, a duty ratio is set to measure an output brightness value of an LDR projector, so as to obtain a sample point, and a plurality of sample point data are collected, so as to obtain a corresponding relationship between the duty ratio of the modulated pulse signal and the output brightness of the LDR projector. Therefore, the mapping relation between the maximum output brightness required by each frame of the image and the pulse duty ratio of the pulse control signal can be obtained.

This relationship may be presented in the form of a correspondence table, or in the form of a graph as shown in fig. 3, which is not limited by the present invention.

The mapping is sent to the control hardware in the form of a digital signal when needed, e.g. when modulation is needed, from which the control hardware generates the control signal.

In another specific example, the control hardware 16 is a single chip, and the mapping relationship may be hard-programmed in Flash in the single chip.

In another specific example, where the control hardware 16 is a microprocessor, the mapping may be a data graph as shown in FIG. 3 stored in a storage medium.

It will be understood by those skilled in the art that the mapping of the present application is not limited to being presented in the manner described above, whether received externally, hard programmed in a single-chip, or stored in memory is merely a routine undertaking in the art, and the utility model is not intended to be so.

In one specific example, it is set that:

the brightness range of all pixels in the original image in the DCP is 0-standard maximum brightness value, such as 0-255;

the original luminance value of each pixel in the original image in the DCP is defined as B, and the luminance value of the converted first image data (i.e., the video to the LDR) is defined as Bt;

maximum output brightness of LDR projector is LB (full power output)

The adjustable range of the output power of the LDR laser light source is 0-100%

In the prior art projectors, the output power of the laser light source of the LDR projector is constant during the projection. The brightness of the laser light source corresponding to each frame of the image input by each particular LDR projector is constant.

In one embodiment, the control hardware 16 is configured (e.g., executing code hard-coded in Flash) to implement:

s10, obtaining the maximum brightness value-standard maximum brightness value of all pixels in all frame images in the DCP original image (i.e. the original image stored in the image memory).

S12, obtaining the maximum brightness of the pixel in a frame or a group of continuous frames from the frame image or a group of continuous frames

The value Bmax is obtained, so that the brightness ratio R of the brightest pixel is obtained_MB＝(B_maxStandard maximum brightness value) 100%.

Specifically, the maximum luminance value of all pixels in one frame image of the digital cinema package is acquired, or the maximum luminance value of all pixels in one shot image (referred to as a group of continuous frame images in this scheme) in succession is acquired. It is understood by those skilled in the art that the term "a shot image" refers to a continuous image, such as, in a movie, a flower in a frame, then the frame is switched to a girl's face, then the girl from a distance squats in a flower stand, then the frame of the girl's face counts as a shot, the previous frame counts as a shot, and so on.

Specifically, the maximum value is selected by comparing all the luminance values.

Then, the laser power output ratio for each frame or consecutive frames is determined by the following two steps:

s14, calculating the maximum output brightness B required by the frame or the continuous frames_frame＝R_MB*LB；

S16, determining B according to the mapping relation_frameA corresponding pulse width duty cycle;

and S18, outputting the control signal according to the duty ratio.

Through the steps, the improvement of the sequential contrast between frames is realized by adjusting the output brightness corresponding to each frame or continuous frames.

For example, the previous frame is a very bright scene with a luminance near 100%, and the next frame is a night with a luminance near all-black 0.

With existing methods, the projector laser light source is always constantly outputting, e.g., at full power, i.e., 100% bright. When light from the light source is directed through the optical path to the mirror array of the DMD of the projector, each mirror is capable of rotating at two deflection angles of +12 degrees and-12 degrees, assuming two states of on and off for the incident light). When the frame image is a very bright scene, the light emitted by the laser light source can be effectively utilized. However, for a scene with night brightness, although the mirror is in an off state, since light that the laser light source still outputs at a constant power into the mirror array still leaks light, a black picture is affected by the light leakage and cannot approach full black. Thus, the bright-dark contrast between two frames is impaired.

By using the control hardware of the present application, the required pulse modulation duty ratio is dynamically analyzed according to the maximum output brightness required by each frame of image, so as to adjust the output power of the laser light source (real-time analysis), for example, as can be seen from fig. 3, when the frame image is a very bright scene (the required maximum output brightness is large), the required pulse modulation duty ratio is also large, and thus the output power of the laser light source is also increased. Conversely, when the frame image is a very dark scene (the required maximum output brightness is small), the required pulse modulation duty ratio is also small, and the output power of the laser light source is also reduced. Therefore, the improvement of the inter-frame sequential contrast is realized. In addition, the constant full-power output of the laser light source is not needed, so that the service life of the laser light source is greatly prolonged. In addition, because the mapping relation is obtained through tests aiming at each specific projector, accurate control can be achieved by sampling enough sample points.

Further, the control hardware 16 is also configured to: after the step S16 of the following,

s17, converting the brightness value B of each pixel in the frame into Bt ═ B/R_MB＝B standard maximum brightness

Value of/B_maxThereby generating the first image data to send to the LDR projector (real-time processing)

By the above steps, the compensation of the bright area in each frame is changed to the standard maximum brightness value, the compensation of the dark area is not compensated, and the compensation of the gray area is reduced (which can be realized by changing the change of the rotation frequency of the DMD small mirror). By stretching and converting the brightness of all pixels in the frame, the contrast in the frame is improved.

In the above scheme, the control signal to the light source of the projector and the synchronization of the light from the LDR and HDR projectors may be implemented by a frame synchronization technique, which belongs to the common general knowledge in the art and is not described herein again.

In fact, as can be seen from the above examples, how to adjust the light-emitting brightness of the projector by using the mapping relationship of the present application and the above method is only a preferred embodiment, and a person skilled in the art can adjust the light-emitting brightness according to other ways as long as the pixel brightness of the projected image can be obtained, and the light-emitting power of the projector is adjusted by a modulation power supply, such as a pulse width modulator, so that the area of the projected image that needs to be bright is brighter and the area that needs to be dark is darker.

Optionally, the control hardware 16 is further configured to send a brightness control signal to the high dynamic range projector if it is determined that the peak brightness of the frame images of the digital cinema package exceeds the upper dynamic range limit of the low dynamic range projector. If not, the brightness control signal is not sent.

Second embodiment-Pre-analysis, real-time processing

Fig. 4 schematically illustrates a second embodiment of a digital cinema projection system comprising an LDR projector and an HDR projector. Please note that, the same or similar schemes as the first embodiment are not repeated or briefly described in this embodiment.

Digital cinema projection system 2 includes one LDR projector 20 and one HDR projector 22 configured to receive first image data (i.e., "video to LDR" in fig. 4) and second image data (i.e., "video to HDR" in fig. 4), respectively, and cause light projected by the LDR projector and the HDR projector to be combined into a projected image for viewing.

The digital cinema projection system 2 further comprises a modulation power supply 24 for modulating the brightness of the projected light of the LDR projector in accordance with a control signal. Optionally, the modulation power supply is a pulse width modulator, and the brightness of the light source in the LDR projector is modulated by changing a pulse width duty ratio.

Digital cinema projection system 2 further comprises control hardware 26 configured to receive the digital cinema package, wherein the digital cinema package contains the control signal sent to the modulated power supply; and configured to generate the first image data and the second image data for transmission to the low dynamic range projector and the high dynamic range projector, respectively, for projection. Wherein the first image data is obtained by converting the brightness value of each pixel in each frame of the original image in step S17 in the first embodiment; the second data image may be obtained by changing all regions of the original image other than the region where the peak luminance exceeds the upper limit of the LDR dynamic range to black.

In this embodiment, the control signal for modulating the modulated power source may be directly encoded in advance (analyzed in advance) when the digital cinema package is produced, for example, pulse width modulation duty ratio data is obtained on the basis of the mapping relationship in the first embodiment, and the duty ratio data is directly encoded in synchronization with the first image data and the second image data in DCP format by using a frame synchronization technique and stored in an image memory of a cinema. The IMB, when decoding, sends the control signal directly to the modulation power supply. The luminance value of each pixel in each frame of the original image is converted by step S17 in the first embodiment to obtain first image data (real-time processing).

Optionally, the modulation power supply 24 is a pulse width modulator, comprising a power supply controller and a duty cycle varying unit. The power supply controller is used for receiving the control data and generating a control signal, and instructs the duty ratio changing unit to change the duty ratio of the pulse signal.

Other alternative examples of the first embodiment may also be applied to the second embodiment without violating logic.

Third embodiment-Pre-analysis, Pre-processing

Fig. 5 schematically illustrates a third embodiment of a digital cinema projection system comprising an LDR projector and an HDR projector. Please note that, the same or similar schemes as the first embodiment are not repeated or briefly described in this embodiment.

Digital cinema projection system 3 comprises one LDR projector 30 and one HDR projector 32 configured to receive first image data (i.e. "video to LDR" in fig. 5) and second image data (i.e. "video to HDR" in fig. 5), respectively, and to cause light projected by the LDR projector and HDR projector to be combined into a projected image for viewing.

The digital cinema projection system 3 further comprises a modulation power supply 34 for modulating the brightness of the projected light of the LDR projector in accordance with a control signal. Optionally, the modulation power supply is a pulse width modulator, and the brightness of the light source in the LDR projector is modulated by changing a pulse width duty ratio.

The system is configured to receive a digital cinema package from an IMB. In the present embodiment, the digital cinema package contains the first image data, the second image data, and the control signal and the first image data, the second image data, and the control signal are transmitted to the low dynamic range projector, the high dynamic range projector, and the modulation power supply, respectively.

The first image data obtained by modulating the control signal of the modulation power supply and converting the brightness value of each pixel in each frame of the original image in step S17 in the first embodiment is directly encoded therein in advance (pre-analysis, pre-processing) when the digital cinema package is produced, and the second image data can also be directly encoded therein in advance when the digital cinema package is produced. Such digital cinema packages may be stored in an image storage of a theater. The IMB, when decoding, sends the control signal directly to the modulation power supply. Sending the first image data and the second image data to the low dynamic range projector and the high dynamic range projector, respectively.

In the scheme, control hardware is not needed, and the method is suitable for film companies with digital film package plate making.

Alternatively, in this scheme, the luminance control signal for the HDR projector may also be encoded directly in the DCP.

Other alternative examples of the first embodiment may also be applied to the second embodiment without violating logic.

In the description of the present invention, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it is obvious for a person skilled in the art to make other variations or changes based on the above description, and all embodiments cannot be exhaustive here, and all obvious variations or changes that belong to the technical solutions of the present invention are still in the scope of protection of the present invention.

Claims (1)

1. A digital cinema projection system, comprising:

at least one low dynamic range projector and at least one high dynamic range projector, wherein the system receives a digital cinema package and sends first image data and second image data to the low dynamic range projector and the high dynamic range projector, respectively, the light projected by the low dynamic range projector and the high dynamic range projector being combined into a projected image for viewing;

a modulation power supply for modulating the brightness of the projected light of the low dynamic range projector in accordance with a control signal.

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