CN102694999B - Selecting method and selecting device for light energy conversion gain of photodiode in CMOS (complementary metal oxide semiconductor) sensor - Google Patents
Selecting method and selecting device for light energy conversion gain of photodiode in CMOS (complementary metal oxide semiconductor) sensor Download PDFInfo
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Abstract
The invention discloses a selecting method and a selecting device for light energy conversion gain of a photodiode in a CMOS (complementary metal oxide semiconductor) sensor. The selecting method includes: computing a light intensity value, wherein the light intensity is related to image brightness Y, exposure time TEXP and current light energy conversion gain FD and second gain of the photodiode; and selecting the light energy conversion gain matched with the light intensity value from a light energy conversion gain series, wherein the light energy conversion gain series comprises at least two types of light energy conversion gain. The selecting device comprises a light intensity value computing unit and a light energy conversion gain selecting unit. According to the method and the device, the proper light energy conversion gain can be intelligently selected according to different light intensities, so that the contradictions of yellow belts in highlight and poor sensitivity in dark light can be effectively overcome.
Description
Technical field
The present invention relates to cmos sensor, particularly relate to light energy conversion gain selection method and the device of light sensitive diode in cmos sensor.
Background technology
Integrated circuit technique gos deep into every field.In imaging field, CCD and cmos sensor are the two kinds of imageing sensors be generally used, both utilize light sensitive diode (photodiode) to carry out opto-electronic conversion, image is converted to numerical data, its Main Differences is that the mode that numerical data transmits is different.In ccd sensor, in every a line, the charge data of each pixel can be sent in next pixel successively, is exported by lowermost end part, then carries out amplification output via the amplifier of sensors edges; In cmos sensor, each pixel can adjoin an amplifier and A/D change-over circuit, data is exported by the mode of similar main memory circuit.Compared with traditional CCD technology, cmos sensor can meet the quality requirements that user constantly promotes in various applications better, as image capture, higher sensitivity, wider dynamic range, higher resolution, lower power consumption and the more excellent system integration etc. more flexibly, therefore generally had an optimistic view of by people.
The main composition of cmos sensor imaging is pixel.The quantity of pixel, size and interval determine the resolution of the image that image device produces.Produce pixel by incident light photons being converted to current signal, the signal that general each pixel produces is very little, need change pixel signal intensities by the gain of adjustment photoelectric conversion.
In the cmos sensor of line mode exposure, can produce yellowish leukorrhea when obtaining view data using fluorescent lamp as light source, its basic reason is the light energy difference impinging upon pixel in different rows, causes the difference of image brightness.Because fluorescent lamp have employed the power supply of 50/60HZ, the light energy of generation is the semicircle waveform of 100/120HZ.In order to make the energy that accepts between different rows identical, even if it is different to make every a line expose starting point, but the light energy accepted is identical, and the time for exposure must be integral multiple time in light energy cycle.But when outside light intensity is very strong, image overexposure will be caused.If now the light energy conversion gain of light sensitive diode is lower, just can reasonablely address this problem.
Sensitivity under half-light is another important indicator of transducer, and sensitivity is higher, and details expressive force is better.Now require that the light energy conversion gain of light sensitive diode is more high better.
How to solve the yellowish leukorrhea under high light and the insufficient sensitivity under half-light this to the contradiction being difficult to be in harmonious proportion, become the difficult problem that those skilled in the art are urgently to be resolved hurrily.
Authorization Notice No. is in the Chinese patent of CN100361020C, discloses more related contents.
Summary of the invention
Technical problem to be solved by this invention is to provide system of selection and the device of the light energy conversion gain of light sensitive diode in a kind of cmos sensor, according to different light intensity, can intelligently select suitable light energy conversion gain.
In order to solve the problems of the technologies described above, the invention provides the light energy conversion gain selection method of light sensitive diode in a kind of cmos sensor, comprising:
Calculate light intensity value, current light energy conversion gain FD and the second gain G AIN of described light intensity value and image brightness Y, time for exposure TEXP, light sensitive diode are relevant;
The light energy conversion gain of mating with described light intensity value is selected from the light energy conversion gain series that described light sensitive diode possesses; Described light energy conversion gain series at least comprises two kinds of light energy conversion gains.
Optionally, described calculating light intensity value comprises the following steps:
R, G, B component of statistical picture, obtains described image brightness Y;
According to current light energy conversion gain FD and the second gain G AIN of image brightness Y, time for exposure TEXP, light sensitive diode, calculate intensity signal light;
Average to the intensity signal light value of N two field picture, obtain described light intensity value, described N is natural number.
Optionally, R, G, B component of described statistical picture, according to formula: Y=a|R+b|G+c|B calculates, and a, b, c are arithmetic number and a+b+c=1.
Optionally, a is 0.299, b be 0.587, c is 0.114.
Optionally, describedly intensity signal light is calculated, according to formula:
Light=log
2y-log
2tEXP-log
2fD-log
2gAIN+M calculates, and described M is self-defined real number.
Optionally, described M is 40.
Optionally, the size of described N, determines by selecting the frequency of luminous energy conversion gain.
Optionally, the scope of described image brightness Y is 1 ~ 1023, and the scope of described time for exposure TEXP is 1 ~ (256*582*908), and the scope of described light energy conversion gain FD is 1 ~ 10, and the scope of the second described gain G AIN is 1 ~ 51.
Optionally, the second described gain G AIN comprises analog gain, digital gain.
Optionally, the described light energy conversion gain selecting to mate with described light intensity value from the light energy conversion gain series that described light sensitive diode possesses, comprising:
According to the light energy conversion gain that described light energy conversion gain series comprises, arrange Intensity threshold, the number ratio of described light energy conversion gain and described Intensity threshold is (n+1): 2n, n are natural number;
Set up the corresponding relation of Intensity threshold and light energy conversion gain, described Intensity threshold is less, and corresponding light energy conversion gain is higher; 2 kinds of light energy conversion gains that 2 adjacent Intensity thresholds are corresponding adjacent;
According to described light intensity value, determine 2 adjacent Intensity thresholds;
When described light intensity value is less than in adjacent 2 Intensity thresholds less one, select the higher person in corresponding 2 kinds of light energy conversion gains;
When described light intensity value is greater than in adjacent 2 Intensity thresholds larger one, select junior in corresponding 2 kinds of light energy conversion gains;
When described light intensity value is between adjacent 2 Intensity thresholds, according to the gain of described current light energy conversion gain selection light energy conversion.
Optionally, described according to the gain of described current light energy conversion gain selection light energy conversion, comprising: select in corresponding 2 light energy conversion gains with described current light energy conversion gain inequality apart from smaller.
Optionally, n is 2;
Described light energy conversion gain comprises high, medium and low three kinds, and described Intensity threshold comprises the first threshold representing the half-light upper limit, the Second Threshold representing appropriate light lower limit, represents the 3rd threshold value of the appropriate light upper limit and represent the 4th threshold value of high light lower limit;
When described light intensity value is less than or equal to first threshold, select high-light-energy conversion gain;
When described light intensity value is more than or equal to Second Threshold, and when being less than or equal to the 3rd threshold value, light energy conversion gain in selection;
When described light intensity value is more than or equal to the 4th threshold value, select low luminous energy conversion gain;
When described light intensity value is between first threshold and Second Threshold or between the 3rd threshold value and the 4th threshold value, according to the gain of described current light energy conversion gain selection light energy conversion.
Optionally, according to the gain of described current light energy conversion gain selection light energy conversion, comprising:
When described light intensity value is between first threshold and Second Threshold, only when original light energy conversion gain is low luminous energy conversion gain, light energy conversion gain in selection; Otherwise described current light energy conversion gain remains unchanged;
When described light intensity value is between the 3rd threshold value and the 4th threshold value, only when original light energy conversion gain is high-light-energy conversion gain, light energy conversion gain in selection; Otherwise described current light energy conversion gain remains unchanged.
Optionally, first, second, third, fourth described threshold value is in 2 ~ 50 scopes.
Optionally, described light energy conversion gain, is configured by the characteristic parameter of cmos sensor.
Optionally, described light energy conversion gain, when cmos sensor characteristic parameter is certain, needs to carry out fine tune according to user.
Present invention also offers the light energy conversion gain selection device of light sensitive diode in a kind of cmos sensor, comprising: light intensity value computing unit, light energy conversion gain selection unit, wherein:
Light intensity value computing unit, for according to the current light energy conversion gain FD and the second gain G AIN with image brightness Y, time for exposure TEXP, light sensitive diode, calculates light intensity value;
Light energy conversion gain selection unit, for selecting the light energy conversion gain of mating with described light intensity value in the light energy conversion gain series that possesses from described light sensitive diode.
Compared with prior art, the present invention has the following advantages:
1, by analyzing the influencing factor of light intensity value, light intensity value is calculated.Reference light intensity values, intelligently selects suitable light energy conversion gain, to avoid producing the requirement of sensitivity under yellowish leukorrhea and half-light under meeting high light simultaneously.
2, in possibility, after comparing with current light energy conversion gain, select suitable light energy conversion gain again, avoid the problem of the luminous energy conversion gain flicker when light intensity value just in time fluctuates near threshold point.
Accompanying drawing explanation
Fig. 1 is the schematic flow sheet of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 2 is the schematic flow sheet of a kind of embodiment calculating light intensity value in the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 3 is the schematic flow sheet of a kind of embodiment selecting the light energy conversion gain of mating in the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 4 is the result oscillogram of the first embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 5 is the result oscillogram of the second embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 6 is the result oscillogram of the 3rd embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention;
Fig. 7 is the structural representation of the light energy conversion gain selection device of light sensitive diode in cmos sensor of the present invention.
Embodiment
Following elaboration and accompanying drawing will make above-mentioned feature of the present invention and advantage more obvious.This elaboration is intended to the present invention is described, is convenient to fully understand the present invention, and should not be construed as limitation of the invention.Describe in detail below with reference to accompanying drawings according to preferred embodiment of the present invention.
In order to solve the technical problem in background technology, the invention provides the system of selection of the light energy conversion gain of light sensitive diode in a kind of cmos sensor.Fig. 1 is the schematic flow sheet of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention, comprises the following steps:
Perform step S101, calculate light intensity value.
Perform step S102, from light energy conversion gain series, select the light energy conversion gain of mating with described light intensity value.
Fig. 2 is the schematic flow sheet of a kind of embodiment calculating light intensity value in the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention; Composition graphs 1, Fig. 2 illustrate calculating light intensity value.
With reference to figure 2, calculate light intensity value and at least comprise the following steps:
Perform step S201, R, G, B component of statistical graph, obtains image brightness Y.
Perform step S202, according to current light energy conversion gain FD and other gain G AIN of image brightness Y, time for exposure TEXP, light sensitive diode, calculate intensity signal light.
Perform step S203, the intensity signal light of N two field picture is averaged, obtains light intensity value.
Particularly, according to
Y=0.299|R+0.587|G+0.114|B formula 1
Statistics obtains image brightness Y.This formula is the general formula that rgb color model transfers YUV colour model to, and wherein R, G, B are respectively the rgb color component of figure.In YUV color mode, Y represents brightness (Luminance or Luma), namely grey decision-making; U and V represents colourity (Chrominance or Chroma), and effect is color and the saturation of Description Image, is used to specify the color of pixel.In YUV color mode, brightness signal Y is separated with carrier chrominance signal U, V, and brightness Y sets up by RGB input signal, by above-mentioned formula, the specific part of rgb signal can be superimposed together.
It should be noted that, in other embodiment, the weight shared by each color component of RGB need not be defined as 0.299,0.587,0.114, can according to demand under each weight adds up to the prerequisite of 100% from Row sum-equal matrix weight.In other color modes, other statistical formula also can be used to obtain brightness Y.
Inventor analyzes the some questions affecting light intensity, finds that light intensity L comprises analog gain and digital gain primarily of the current light energy conversion gain FD of image brightness Y, time for exposure TEXP, light sensitive diode and the second gain G AIN() four large factors decisions:
Wherein image brightness Y is by described statistics color component gained.Time for exposure TEXP, current light energy conversion gain FD and the internal circuit design of the second gain G AIN all in cmos sensor are relevant.Current light energy conversion gain FD is given by cmos sensor internal circuit, is the one (light energy conversion gain series at least comprises two kinds of light energy conversion gains) in light energy conversion gain series.But the light intensity degree in the external world, may still use high-light-energy conversion gain and cause image overexposure, also may still use low luminous energy conversion gain and make image sensitivity not good enough under half-light under high light when actual use is not considered in this selection.System of selection of the present invention, combines light intensity value, intelligently adjusts, select suitable transform light energy gain FD ' to the current light energy conversion gain FD produced by cmos sensor internal circuit, thus improves picture quality.
To the formula 2 both sides logarithm that to get with 2 be the end:
Log
2l=log
2y-log
2tEXP-log
2fD-log
2gAIN formula 3
In this embodiment, the span of Y is 1 ~ 1023(is 10 in each data of cmos sensor), the span of the span of TEXP to be the span of 1 ~ (256*582*908), FD be 1 ~ 10, GAIN is 1 ~ 51.Above-mentioned span is only for certain specific cmos sensor.In conjunction with the circuit design characteristic of itself, the restriction meeting cmos sensor requirement can be made to above-mentioned span for other cmos sensors.
Can estimate in conjunction with above-mentioned span, log
2the span of L is-38 ~ 10.For convenience of subsequent calculations, ensure intensity signal light be on the occasion of, on formula 3 basis, therefore add a concrete real number.In this embodiment, this real number is 40(formula 4).So the span of intensity signal light is 2 ~ 50.The span different according to other cmos sensors, this concrete real number can be different.
Light=log
2l+40 formula 4
The intensity signal light of N two field picture is averaged (formula 5), obtains described light intensity value
Intensity signal is averaged and can be made light intensity value
more level and smooth, avoid the accident error because of certain intensity signal large especially, cause light intensity value
excessive and have influence on the selection of light energy conversion gain FD ' with actual value error.The size of concrete N determines by selecting the frequency of luminous energy conversion gain FD.Frequency is higher, and N value is less.Such as: the light energy conversion gain that TRY ANOTHER SELECTION in every 2 minutes, and the image having 25 ~ 30 frames per second, then N value between (25*2*60) to (30*2*60).N is too small, level and smooth intensity signal, avoids the effect of error effect may be not ideal enough.N is excessive, can have influence on the response speed of image procossing.But concrete N value scope is not specifically limited in this application.
Fig. 3 is the schematic flow sheet of a kind of embodiment selecting the light energy conversion gain of mating in the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention.Composition graphs 1, Fig. 3 illustrate the light energy conversion gain selecting coupling.
With reference to figure 3, the light energy conversion gain of coupling is selected at least to comprise the following steps:
Perform step S301, according to the light energy conversion gain that light energy conversion gain series comprises, arrange Intensity threshold, the number ratio of light energy conversion gain and Intensity threshold is (n+1): 2n;
Perform step S302, set up the corresponding relation of Intensity threshold and light energy conversion gain, Intensity threshold is less, and corresponding light energy conversion gain is higher, 2 kinds of light energy conversion gains that 2 adjacent Intensity thresholds are corresponding adjacent;
Perform step S303, according to described light intensity value, determine adjacent 2 Intensity thresholds.
According to the relation of light intensity value and adjacent 2 Intensity thresholds, points of 3 kinds different dispositions.
1, perform step S304, judge whether light intensity value is less than in adjacent 2 each Intensity thresholds less one.If so, then perform step S307, select the higher person in corresponding 2 kinds of light energy conversion gains.
2, perform step S305, judge light intensity value whether between adjacent 2 Intensity thresholds.If so, then step S308 is performed, according to the gain of current light energy conversion gain selection light energy conversion.Particularly, in this embodiment, select in corresponding 2 light energy conversion gains with described current light energy conversion gain inequality apart from smaller.Why needing to compare with current light energy conversion gain, is because when light intensity value fluctuates at Near Threshold, can cause frequently changing between 2 different light energy conversion gains, generation scintillation.By comparing with current light energy conversion gain, continuing to use current light energy conversion gain as far as possible, can effectively avoid above-mentioned scintillation.
3, perform step S306, judge whether light intensity value is greater than in adjacent 2 Intensity thresholds larger one.If so, then perform step S309, select junior in corresponding 2 kinds of light energy conversion gains.
It should be noted that, described light energy conversion gain is configured by the characteristic parameter of cmos sensor.Further, when cmos sensor characteristic parameter is certain, can also need to carry out fine tune according to user.
Fig. 4 is the result oscillogram of the first embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention.In the present embodiment, n is 1, and namely light energy conversion gain series comprises 2 kinds of light energy conversion gains, is therefore provided with 2 Intensity thresholds.Abscissa with reference to figure 4, Fig. 4 represents light intensity value.Abscissa there are 2 Intensity thresholds, first threshold Lth1 and Second Threshold Lth2, first threshold Lth1< Second Threshold Lth2.The ordinate of Fig. 4 represents light energy conversion gain.Ordinate there are 2 kinds of light energy conversion gains, low luminous energy conversion gain fd1 and high-light-energy conversion gain fd0.
When the light intensity value calculating gained is less than first threshold Lth1, select high-light-energy conversion gain fd0.When light intensity value is between first threshold Lth1 and Second Threshold Lth2, need with reference to current light energy conversion gain FD.When current light energy conversion gain FD is high-light-energy conversion gain fd0, select high-light-energy conversion gain fd0(because | fd0-fd0|<|fd1-fd0|).In like manner, current light energy conversion gain FD is low luminous energy conversion gain fd1 is select low luminous energy conversion gain fd1.When the light intensity value calculating gained is greater than Second Threshold Lth2, select low luminous energy conversion gain fd1.
Fig. 5 is the result oscillogram of the second embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention.In the present embodiment, n is 2, and namely light energy conversion gain series comprises 3 kinds of light energy conversion gains, is therefore provided with 4 Intensity thresholds.The abscissa of Fig. 5 there are 4 threshold values, first threshold Lth1< Second Threshold Lth2< the 3rd threshold value Lth3< the 4th threshold value Lth4, represents the half-light upper limit, appropriate light lower limit, the appropriate light upper limit and high light lower limit successively.In the present embodiment, the value of 4 threshold values is between 2 ~ 50.The ordinate of Fig. 5 there are 3 value fd0, fd1, fd2, represent high-light-energy conversion gain, middle light energy conversion gain, low luminous energy conversion gain respectively.2 adjacent Intensity threshold first threshold Lth1 and Second Threshold Lth2, corresponding high-light-energy conversion gain fd0 and middle light energy conversion gain fd1.Another 2 adjacent Intensity threshold the 3rd threshold value Lth3 and the 4th threshold value Lth4, light energy conversion gain fd1 and low luminous energy conversion gain fd2 in correspondence.
When light intensity value is less than first threshold Lth1, namely during half-light, select high-light-energy conversion gain fd0, to increase the signal strength signal intensity of pixel, improve the sensitivity under transducer half-light.
When light intensity value is between Second Threshold Lth2 and the 3rd threshold value Lth3, namely during appropriate light, light energy conversion gain fd1 in selection.
When light intensity value is greater than the 4th threshold value Lth4, namely high smooth time, select low luminous energy conversion gain fd2, weaken the signal strength signal intensity of pixel, to prevent image overexposure.
When light intensity value is between half-light and appropriate light between first threshold Lth1 and Second Threshold Lth2, or when being between appropriate light and Gao Guang between the 3rd threshold value Lth3 and the 4th threshold value Lth4, need select according to current light energy conversion gain.
Particularly, when light intensity value is between first threshold Lth1 and Second Threshold Lth2, namely time between half-light and appropriate light, because the light energy conversion gain that first threshold Lth1 and Second Threshold Lth2 is corresponding is high-light-energy conversion gain fd0 and middle light energy conversion gain fd1, so now optional light energy conversion gain is only limitted to these 2 kinds, and can not be low luminous energy conversion gain fd2.When current light energy conversion gain is low luminous energy conversion gain fd2, due to | fd1-fd2|<|fd0-fd2|, so light energy conversion gain fd1 in selecting.When current light energy conversion gain is middle light energy conversion gain fd1, due to | fd1-fd1|<|fd0-fd1|, so light energy conversion gain fd1 in selecting.When current light energy conversion gain is high-light-energy conversion gain fd0, due to | fd0-fd0|<|fd1-fd0|, so select high-light-energy conversion gain fd0.
When light intensity value is between the 3rd threshold value Lth3 and the 4th threshold value Lth4, namely time between appropriate light and Gao Guang, because the light energy conversion gain that the 3rd threshold value Lth3 and the 4th threshold value Lth4 is corresponding is middle light energy conversion gain fd1 and low luminous energy conversion gain fd2, so now optional light energy conversion gain is only limitted to these 2 kinds, and can not be high-light-energy conversion gain fd0.When current light energy conversion gain is low luminous energy conversion gain fd2, due to | fd2-fd2|<|fd1-fd2|, so select low luminous energy conversion gain fd2.When current light energy conversion gain is middle light energy conversion gain fd1, due to | fd1-fd1|<|fd2-fd1|, so light energy conversion gain fd1 in selecting.When current light energy conversion gain is high-light-energy conversion gain fd0, due to | fd1-fd0|<|fd2-fd0|, so light energy conversion gain fd1 in selecting.
By comparing with current light energy conversion gain, only when current light energy conversion gain significant discomfort is closed, just reselect new transform light energy gain.In other situations, keep current light energy conversion gain as far as possible, effectively can avoid scintillation.
Fig. 6 is the result oscillogram of the 3rd embodiment of the light energy conversion gain selection method of light sensitive diode in cmos sensor of the present invention.In the present embodiment, n is 3, and namely light energy conversion gain series comprises 4 kinds of light energy conversion gains, is therefore provided with 6 Intensity thresholds.The abscissa of Fig. 6 there are 6 threshold values, first threshold Lth1< Second Threshold Lth2< the 3rd threshold value Lth3< the 4th threshold value Lth4< the 5th threshold value Lth5< the 6th threshold value Lth6.The ordinate of Fig. 6 has 4 light energy conversion gains, namely high-light-energy conversion gain fd0, middle high-light-energy conversion gain fd1, in low luminous energy conversion gain fd2, low luminous energy conversion gain fd3.Adjacent first threshold Lth1 and Second Threshold Lth2, corresponding high-light-energy conversion gain fd0 and middle high-light-energy conversion gain fd1.The 3rd adjacent threshold value Lth3 and the 4th threshold value Lth4, in correspondence high-light-energy conversion gain fd1 and in low luminous energy conversion gain fd2.The 5th adjacent threshold value Lth5 and the 6th threshold value Lth6, low luminous energy conversion gain fd2 and low luminous energy conversion gain fd3 in correspondence.
With precedent similar portions, repeat no more, the situation of main explanation light intensity value between 2 threshold values herein.
When light intensity value is between first threshold Lth1 and Second Threshold Lth2, because first threshold and light energy conversion gain corresponding to Second Threshold are high-light-energy conversion gain fd0 and middle high-light-energy conversion gain fd1, so now optional light energy conversion gain is only limitted to these 2 kinds.When current light energy conversion gain is low luminous energy conversion gain fd3, due to | fd1-fd3|<|fd0-fd3|, so high-light-energy conversion gain fd1 in selecting.Current light energy conversion gain be in low luminous energy conversion gain fd2 time, due to | fd1-fd2|<|fd0-fd2|, so high-light-energy conversion gain fd1 in selecting.When current light energy conversion gain is middle high-light-energy conversion gain fd1, due to | fd1-fd1|<|fd0-fd1|, so high-light-energy conversion gain fd1 in selecting.When current light energy conversion gain is high-light-energy conversion gain fd0, due to | fd0-fd0|<|fd1-fd0|, so select high-light-energy conversion gain fd0.
When light intensity value is between the 3rd threshold value Lth3 and the 4th threshold value Lth4, due to light energy conversion gain that the 3rd threshold value Lth3 and the 4th threshold value Lth4 is corresponding be middle high-light-energy conversion gain fd1 and in low luminous energy conversion gain fd2, so now optional light energy conversion gain is only limitted to these 2 kinds.When current light energy conversion gain is low luminous energy conversion gain fd3, due to | fd2-fd3|<|fd1-fd3|, so low luminous energy conversion gain fd2 in selecting.Current light energy conversion gain be in low luminous energy conversion gain fd2 time, due to | fd2-fd2|<|fd1-fd2|, so low luminous energy conversion gain fd2 in selecting.When current light energy conversion gain is middle high-light-energy conversion gain fd1, due to | fd1-fd1|<|fd2-fd1|, so high-light-energy conversion gain fd1 in selecting.When current light energy conversion gain is high-light-energy conversion gain fd0, due to | fd1-fd0|<|fd2-fd0|, so high-light-energy conversion gain fd1 in selecting.
When light intensity value is between the 5th threshold value Lth5 and the 6th threshold value Lth6, due to light energy conversion gain that the 5th threshold value Lth5 and the 6th threshold value Lth6 is corresponding be in low luminous energy conversion gain fd2 and low luminous energy conversion gain fd3, so now optional light energy conversion gain is only limitted to these 2 kinds.When current light energy conversion gain is low luminous energy conversion gain fd3, due to | fd3-fd3|<|fd2-fd3|, so select low luminous energy conversion gain fd3.Current light energy conversion gain be in low luminous energy conversion gain fd2 time, due to | fd2-fd2|<|fd3-fd2|, so low luminous energy conversion gain fd2 in selecting.When current light energy conversion gain is middle high-light-energy conversion gain fd1, due to | fd2-fd1|<|fd3-fd1|, so low luminous energy conversion gain fd2 in selecting.When current light energy conversion gain is high-light-energy conversion gain fd0, due to | fd2-fd0|<|fd3-fd0|, so low luminous energy conversion gain fd2 in selecting.
Fig. 7 is the structural representation of the light energy conversion gain selection device of light sensitive diode in cmos sensor of the present invention, comprises light intensity value computing unit 100, light energy conversion gain selection unit 200.RGB component, time for exposure TEXP, current light energy conversion gain FD and the second gain G AIN, as input signal, enter light intensity value computing unit 100.Current light energy conversion gain FD is simultaneously also as the input signal of light energy conversion gain selection unit.Light energy conversion gain selection unit 200 also accepts the output signal light intensity value of light intensity value computing unit 100
as input signal.Light energy conversion gain selection unit 200 is in conjunction with light intensity value
current light energy conversion gain FD is adjusted, light energy output conversion gain FD '.
Disclose as above with preferred embodiment although the present invention is own, the present invention is not defined in this.Any those skilled in the art, without departing from the spirit and scope of the present invention, all can make various changes or modifications, and therefore protection scope of the present invention should be as the criterion with claim limited range.
Claims (12)
1. the light energy conversion gain selection method of light sensitive diode in cmos sensor, is characterized in that:
Calculate light intensity value, current light energy conversion gain FD and the second gain G AIN of described light intensity value and image brightness Y, time for exposure TEXP, light sensitive diode are relevant, comprise step: R, G, B component of statistical picture, obtains described image brightness; According to current light energy conversion gain and second gain of image brightness, time for exposure, light sensitive diode, and formula:
Light=log
2y-log
2tEXP-log
2fD-log
2gAIN+M, calculates intensity signal light, and wherein said M is self-defined real number; Average to the intensity signal of N two field picture, obtain described light intensity value, described N is natural number;
The light energy conversion gain of mating with described light intensity value is selected from the light energy conversion gain series that described light sensitive diode possesses, described light energy conversion gain series at least comprises two kinds of light energy conversion gains, comprise step: the light energy conversion gain comprised according to described light energy conversion gain series, Intensity threshold is set, the number ratio of described light energy conversion gain and described Intensity threshold is (n+1): 2n, n are natural number; Set up the corresponding relation of Intensity threshold and light energy conversion gain, described Intensity threshold is less, and corresponding light energy conversion gain is higher; 2 kinds of light energy conversion gains that 2 adjacent Intensity thresholds are corresponding adjacent; According to described light intensity value, determine 2 adjacent Intensity thresholds; When described light intensity value is less than in adjacent 2 Intensity thresholds less one, select the higher person in corresponding 2 kinds of light energy conversion gains; When described light intensity value is greater than in adjacent 2 Intensity thresholds larger one, select junior in corresponding 2 kinds of light energy conversion gains; When described light intensity value is between adjacent 2 Intensity thresholds, select in corresponding 2 light energy conversion gains with described current light energy conversion gain inequality apart from smaller.
2. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that:
R, G, B component of described statistical picture, according to formula: Y=a|R+b|G+c|B calculates, and a, b, c are arithmetic number and a+b+c=1.
3. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 2, is characterized in that: a is 0.299, b be 0.587, c is 0.114.
4. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that: described M is 40.
5. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that:
The size of described N, determines by selecting the frequency of luminous energy conversion gain.
6. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that:
The scope of described image brightness is 1 ~ 1023, and the scope of described time for exposure is 1 ~ (256*582*908), and the scope of described light energy conversion gain is 1 ~ 10, and the scope of the second described gain is 1 ~ 51.
7. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that: the second described gain comprises analog gain and digital gain.
8. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that:
N is 2;
Described light energy conversion gain comprises high, medium and low three kinds, and described Intensity threshold comprises the first threshold representing the half-light upper limit, the Second Threshold representing appropriate light lower limit, represents the 3rd threshold value of the appropriate light upper limit and represent the 4th threshold value of high light lower limit;
When described light intensity value is less than or equal to first threshold, select high-light-energy conversion gain;
When described light intensity value is more than or equal to Second Threshold, and when being less than or equal to the 3rd threshold value, light energy conversion gain in selection;
When described light intensity value is more than or equal to the 4th threshold value, select low luminous energy conversion gain;
When described light intensity value is between first threshold and Second Threshold or between the 3rd threshold value and the 4th threshold value, according to the gain of described current light energy conversion gain selection transform light energy, comprising:
When described light intensity value is between first threshold and Second Threshold, only when original light energy conversion gain is low luminous energy conversion gain, light energy conversion gain in selection; Otherwise described current light energy conversion gain remains unchanged;
When described light intensity value is between the 3rd threshold value and the 4th threshold value, only when original light energy conversion gain is high-light-energy conversion gain, light energy conversion gain in selection; Otherwise described current light energy conversion gain remains unchanged.
9. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 8, is characterized in that:
First, second, third, fourth described threshold value is in 2 ~ 50 scopes.
10. the light energy conversion gain selection method of light sensitive diode in cmos sensor as claimed in claim 1, is characterized in that:
Described light energy conversion gain, is configured by the characteristic parameter of cmos sensor.
The light energy conversion gain selection method of light sensitive diode in 11. cmos sensors as claimed in claim 1, is characterized in that:
Described light energy conversion gain, when cmos sensor characteristic parameter is certain, needs to carry out fine tune according to user.
The light energy conversion gain selection device of light sensitive diode in 12. 1 kinds of cmos sensors, is characterized in that, comprising: light intensity value computing unit, light energy conversion gain selection unit, wherein:
Light intensity value computing unit, for calculating light intensity value, current light energy conversion gain FD and the second gain G AIN of described light intensity value and image brightness Y, time for exposure TEXP, light sensitive diode are relevant, comprising: R, G, B component of statistical picture, obtains described image brightness; According to current light energy conversion gain and second gain of image brightness, time for exposure, light sensitive diode, and formula:
Light=log
2y-log
2tEXP-log
2fD-log
2gAIN+M, calculates intensity signal light, and wherein said M is self-defined real number; Average to the intensity signal of N two field picture, obtain described light intensity value, described N is natural number;
Light energy conversion gain selection unit, for selecting the light energy conversion gain of mating with described light intensity value in the light energy conversion gain series that possesses from described light sensitive diode, comprise: the light energy conversion gain comprised according to described light energy conversion gain series, Intensity threshold is set, the number ratio of described light energy conversion gain and described Intensity threshold is (n+1): 2n, n are natural number; Set up the corresponding relation of Intensity threshold and light energy conversion gain, described Intensity threshold is less, and corresponding light energy conversion gain is higher; 2 kinds of light energy conversion gains that 2 adjacent Intensity thresholds are corresponding adjacent; According to described light intensity value, determine 2 adjacent Intensity thresholds; When described light intensity value is less than in adjacent 2 Intensity thresholds less one, select the higher person in corresponding 2 kinds of light energy conversion gains; When described light intensity value is greater than in adjacent 2 Intensity thresholds larger one, select junior in corresponding 2 kinds of light energy conversion gains; When described light intensity value is between adjacent 2 Intensity thresholds, select in corresponding 2 light energy conversion gains with described current light energy conversion gain inequality apart from smaller.
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