JPH11155108A - Video signal processing apparatus and processing method, video camera using the same - Google Patents

Abstract

(57) [Problem] To provide a video signal processing device capable of generating a video signal having a wide dynamic range. SOLUTION: For the same scene, a standard exposure video signal photographed with a standard exposure time and a non-standard exposure video signal photographed with an exposure time shorter than the standard exposure video signal are generated, and these are used. In a video signal processing apparatus for synthesizing a video signal having an expanded dynamic range, a gain adjusting means 1110 for performing gain adjustment on a non-standard exposure video signal according to an exposure time ratio between a standard exposure video signal and a non-standard exposure video signal. And a video signal synthesizing unit 1080 for generating a high dynamic range synthesized video signal by synthesizing the standard exposure video signal and the non-standard exposure video signal whose gain has been adjusted according to the signal level. It is possible to obtain a video signal of a wide dynamic range with a natural gradation from a low luminance range to a high luminance range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing apparatus for processing a video signal projected by a photographing element, a video signal processing method thereof, and a video camera using the same, and more particularly to a video with a wide dynamic range. The signal can be synthesized.

[0002]

2. Description of the Related Art In recent years, solid-state image sensors such as CCD image sensors have been widely used as image capturing means for video cameras and electronic still cameras.

However, the dynamic range of this solid-state imaging device is narrower than that of a silver halide photograph or the like, and when a subject having a large contrast ratio is imaged, a bright portion becomes uniformly whitish, that is, a so-called white loss or darkness. The portion becomes uniformly dark, that is, so-called underexposure appears in the image, and the image quality is significantly deteriorated.

Conventionally, as a method of expanding the dynamic range of an image, a method described in Japanese Patent Application Laid-Open No. Hei 7-131718 is known. In this method, the same scene is photographed with different exposure amounts, and video signals with different exposure amounts are combined to generate a video signal with an expanded dynamic range. After providing a common combining area for the signals and adjusting the signal level, video signals having different exposure amounts are combined.

However, when this method is simply applied to a three-panel video camera and a single-panel video camera of the RGB processing system, faithful color reproduction cannot be performed and false colors may be generated.

FIG. 9 shows a video signal processing apparatus of a three-panel video camera to which the dynamic range expansion method is applied. Here, the case of the dynamic range expansion processing in frame units will be described.

This apparatus includes a prism 1000 for separating light into R, G, and B, and a prism 1000 for converting the amount of light separated into three systems of R, G, and B into an electric signal and different exposure times. The three image pickup devices 1010 for each RGB, which output video signals (a video signal at the time of standard exposure and a video signal at the time of non-standard exposure) for each frame, and drive the image pickup device 1010 to output the video signal of the standard exposure and the non-standard In addition to controlling the timing at which the video signal of the standard exposure is generated, as shown in FIG.
An image pickup device driving unit 1020 that generates 21 and outputs it to each synchronization unit 1050, and a preprocessing unit 1030 that removes noise of the video signal output from the image pickup device 1010, adjusts the amplitude, and clamps to a predetermined level. An A / D converter 1040 for converting the output of the preprocessing means 1030 into a digital video signal, and a synchronizing means 1050 for outputting the standard exposure video signal and the non-standard exposure video signal converted into the digital video signal at the same timing.
And standard exposure video signal 1060 and non-standard exposure video signal 1070
Signal synthesizing means 1080 for synthesizing video and video signal synthesizing means
Gamma correction, contour correction, etc. are performed on the composite video signal 1081 output from the 1081, and a luminance signal, a color difference signal, R,
A camera process 1090 for generating G, B, etc. output signals.

The pre-processing means 1030 includes a CDS means for removing noise components of the analog signal output from the image sensor 1010 by correlated double sampling, and a means for maintaining the analog video signal from which the noise components have been removed at a constant signal level. AGC means for adjusting the amplitude of the analog video signal, a clamp circuit for performing a clamp process on the analog video signal whose amplitude has been adjusted, and the like, for performing A / D conversion on the analog video signal output from the image sensor 1010. Perform processing.

The A / D converter 1040 converts the output of each pre-processing unit 1030 into a digital video signal,
Output to The output 1041 of this A / D converter is shown in FIG.
This is shown in FIG.

As shown in FIG. 10A, the synchronizing means 1050 includes a memory means 10511 for delaying a video signal for one frame, a selector means 10513 for selecting and outputting a standard exposure video signal, Selector means 10514 for selecting and outputting the non-standard exposure video signal. The memory unit 10511 delays the A / D converter output 1041 of FIG. 10B by one frame and outputs the result to the selector unit 10513 and the selector unit 10514 as shown in FIG. 10C. According to the exposure time identification signal 1021 output from the element driving means 1020, only the standard exposure video signal is alternately selected and output from the A / D converter output 1041 and the memory means output 10512 (FIG. 10F). Similarly, the selector means 10514 similarly outputs the A / D converter output 1041 and the memory means output 10512 according to the exposure time identification signal 1021.
Then, only the non-standard exposure video signal is alternately selected and output (FIG. 10E). Thus, the standard exposure video signal 1060 and the non-standard exposure video signal 1070 are output from the synchronization unit 1050 to the video signal synthesizing unit 1080 at the same timing.

The video signal synthesizing means 1080 synthesizes the standard exposure video signal 1060 and the non-standard exposure video signal 1070. FIG. 11 shows a state of the synthesis.

In FIG. 11, since the exposure time of the standard exposure video signal 1060 is longer than that of the non-standard exposure video signal 1070, LON
G, and the non-standard exposure video signal 1070 is called SHORT because the exposure time is shorter than the video signal 1060 of the standard exposure.

FIG. 11A is an input / output characteristic showing the relationship between the amount of incident light in LONG and the output level of the image sensor. When the amount of incident light exceeds the amount of saturated light, the output level is saturated at a constant value, and whiteout is likely to occur. However, a normal standard video signal can be obtained up to the saturation light amount.

FIG. 11B shows input / output characteristics of SHORT. By shortening the shutter time from the standard exposure or lowering the sensitivity from LONG, the amount of incident light at which the image sensor is saturated can be increased accordingly. However, the portion where the amount of incident light is small has a poor S / N and tends to be blackened.

Therefore, the dynamic range of the video signal is expanded by utilizing the characteristics of LONG and SHORT.

For example, in a region where LONG is not saturated,
Only LONG is output as an image sensor output, and LONG and SHO are output in a region (MIX region) where LONG begins to saturate.
A value obtained by internally dividing RT with K (video signal synthesis signal) is output, and in a region where LONG is completely saturated, control is performed such that only SHORT is output. K is a control signal for smoothly varying LONG at the lower limit of the MIX area and SHORT at the upper limit.

As shown in FIG. 11 (E), the output level of K indicates the proportion of SHORT included in the composite video signal 1081, so that it is 0 in the LONG area, 0 ≦ K ≦ 1 in the MIX area, It is 1 in the short area.

Here, the synthesized video signal 1081 output from the video signal synthesizing means 1080 is OUT, the start level of the LONG MIX area is Yth, and the saturation level of LONG is SAT.
Assuming that LONG and SHORT intersect in the MIX area and OFSET1 and K are video signal synthesis control signals as offset values for naturally synthesizing video signals, control for obtaining a synthesized video signal 1081 (OUT) is performed. This can be expressed as follows. (1) When LONG ≦ Yth (region where LONG is not saturated K = 0) OUT = LONG (2) When Yth ≦ LONG ≦ SAT (MIX region
0 ≦ K ≦ 1) OUT = (1-K) × LONG + K × (SHORT + O
FSET1) where K = (LONG−Yth) / (SAT−Yt)
h) (3) When LONG ≧ SAT (LONG saturated area K = 1) OUT = SHORT + OFSET1

The composite video signal 10 finally obtained in this way
81 is shown in FIG.

Conventionally, a video signal is synthesized in this way,
A high dynamic range video signal was obtained.

[0021]

However, since the standard exposure video signal and the non-standard exposure video signal have different characteristics of the output of the imaging device with respect to the incident light amount, the standard exposure video signal and the non-standard exposure video signal are different from each other. A composite video signal with a non-standard exposure video signal cannot have a linear characteristic over the entire range from a low luminance region to a high luminance region. Therefore, R, G,
When this composite video signal is generated for each B, the ratio of R, G, B of the incident light amount and R, G,
The ratio of B may be different, and there is a problem that a so-called false color is generated.

This false color is more likely to occur when the dynamic range of the video signal must be limited in accordance with the gradation characteristics of the display device.

The present invention is to solve such a conventional problem, and provides a video signal processing apparatus for generating a video signal having a wide dynamic range with less occurrence of false colors, and a video signal processing method therefor. It is another object of the present invention to provide a video camera capable of faithfully displaying the hue of a subject by such video signal processing.

[0024]

Therefore, according to the video signal processing method of the present invention, the gain for the non-standard exposure video signal is adjusted according to the exposure time ratio between the standard exposure video signal and the non-standard exposure video signal. The standard exposure video signal and the non-standard exposure video signal whose gain has been adjusted are synthesized according to the signal level.

Further, the video signal processing apparatus of the present invention is provided with gain adjusting means for performing the gain adjustment and video signal synthesizing means for performing the synthesizing.

In the video camera of the present invention, the video signal of the image sensor is processed by using the video signal processing device.

Therefore, since the input / output characteristics of the standard exposure video signal before saturation and the input / output characteristics of the gain-adjusted non-standard exposure video signal can be made equal, by synthesizing them, the low-luminance region to the high-luminance region can be obtained. A video signal having a wide dynamic range up to the luminance range can be generated.

Further, by performing this video signal processing with a video camera having an image sensor, a video faithful to the hue of the subject can be displayed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides a standard exposure video signal which is photographed with a standard exposure time for the same scene and a standard exposure video signal which is photographed with a shorter exposure time than the standard exposure video signal. A non-standard exposure video signal is generated, and a video signal processing device that synthesizes a video signal having an expanded dynamic range using the non-standard exposure video signal is used in accordance with an exposure time ratio between the standard exposure video signal and the non-standard exposure video signal. Means for adjusting the gain of the non-standard exposure video signal, and generating a high dynamic range composite video signal by synthesizing the standard exposure video signal and the gain-adjusted non-standard exposure video signal according to the signal level. And a video signal having a wide dynamic range from a low luminance range to a high luminance range.

According to a second aspect of the present invention, the standard exposure video signal and the non-standard exposure video signal are converted into R,
G and B are generated for each, and the gain adjustment means performs gain adjustment for the non-standard exposure video signal for each of R, G and B,
The video signal synthesizing means generates a synthesized video signal for each of R, G, and B, and the ratio of R, G, and B is the same as the hue of the subject, and high dynamics without generating false colors. A range of video signals can be generated.

According to a third aspect of the present invention, there is provided a non-linear processing means for performing non-linear processing on a synthesized video signal generated by the video signal synthesizing means in accordance with a dynamic range of a display device. Even when the dynamic range of the composite video signal is limited in accordance with the gradation characteristics of the device, the occurrence of false colors can be reduced.

According to a fourth aspect of the present invention, a standard exposure video signal obtained by photographing the same scene with a standard exposure time is provided.
In a video signal processing method of generating a non-standard exposure video signal captured with an exposure time shorter than the standard exposure video signal and synthesizing a video signal having an expanded dynamic range using the standard exposure video signal, a non-standard exposure video signal and a non-standard exposure video signal are used. The gain for the non-standard exposure video signal is adjusted according to the exposure time ratio with the video signal, and the standard exposure video signal and the non-standard exposure video signal with the adjusted gain are combined according to the signal level to achieve high dynamics. A composite video signal of a range is generated, and a video signal having a wide dynamic range from a low luminance region to a high luminance region can be generated.

According to a fifth aspect of the present invention, the steps from generation of a standard exposure video signal and a non-standard exposure video signal to generation of a composite video signal are performed for each of R, G, and B in which incident light is separated. Thus, it is possible to generate a video signal with a high dynamic range in which the ratio of R, G, and B is not different from the hue of the subject.

According to a sixth aspect of the present invention, the composite video signal is subjected to a non-linear process in accordance with the dynamic range of the display device. Even when the dynamic range of the signal is limited, a video signal that is almost the same as the hue of the subject can be generated.

According to a seventh aspect of the present invention, there is provided a video camera provided with a solid-state imaging device as a photographing means, wherein the video signal processing device according to any one of the first to third aspects is provided. By expanding the dynamic range of the video signal obtained by the imaging device, it is possible to take a video that faithfully reproduces the hue of the subject.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(First Embodiment) As shown in FIG. 1, a video signal processing apparatus according to a first embodiment converts light into R, G, and B lights.
And two kinds of image signals (image signal 1060 by standard exposure) that convert the light amounts separated into three systems of R, G, and B into electric signals and have different exposure times.
And three image sensors 1010 for each of R, G, and B that alternately output a video signal 1070 due to non-standard exposure in frame units, and drives the image sensors 1010 to control the timing of standard exposure and non-standard exposure. An image sensor driving unit 1020 for outputting an exposure time identification signal 1021 together with the image signal; a pre-processing unit 1030 for performing pre-processing before A / D conversion on a video signal output from the image sensor 1010; A / D converter 1040 for converting the standard exposure video signal 1060 and the non-standard exposure video signal 1070 converted to digital video signals at the same timing.
And the non-standard exposure video signal output from the synchronization means 1050
Gain adjusting means 1110 for adjusting the gain of 1070, and gain adjusting means according to the exposure time ratio between the standard exposure and the non-standard exposure
Exposure ratio calculation means 1100 for controlling the gain of 1110, using the standard exposure video signal 1060 output from the synchronization means 1050 and the non-standard exposure video signal 1070 with the gain output from the gain adjustment means 1110 adjusted Gamma correction, contour correction, and the like are performed on the composite video signal 1081 output from the composite video signal 1081 and the composite video signal 1081 output from the composite video signal 1080 to output luminance signals, color difference signals, R, G, B, and the like. A camera process 1090 for generating a signal.

This apparatus is different from a conventional video signal processing apparatus (FIG. 9) in that a gain adjusting means 1110 and an exposure ratio calculating means are provided.
The difference is that it has the 1100, but the other configurations remain the same.

In this apparatus, the operation until the standard exposure video signal and the non-standard exposure video signal are output from the synchronization means 1050 at the same timing is the same as that of the conventional video signal processing apparatus (FIG. 9). That is, the prism 1000 separates the incident light into R, G, and B light,
As shown in FIG. 2A, an exposure time identification signal 1021 in which the signal level switches between the signal level at the time of standard exposure and the signal level at the time of non-standard exposure for each frame is output to each synchronization means 1050. I do. The signal level during the standard exposure corresponds to the standard exposure time, and the signal level during the non-standard exposure corresponds to the non-standard exposure time.

Each image sensor 1010 converts each of the amounts of R, G, and B light separated by the prism 1000 into an electric signal, and also outputs two types of video signals having different exposure times (a standard exposure video signal 1060 and a non-standard exposure video signal 1060). The standard exposure video signal 1070) is output alternately in frame units.

The preprocessing means 1030 removes noise components of the analog signal output from the image sensor 1010, adjusts the amplitude, and performs a clamp process. The A / D converter 1040 converts the preprocessed analog signal into a digital video signal and outputs the digital video signal to the synchronization means 1050.

As shown in FIG. 10A, the synchronizing means 1050 includes a memory means 10511, a selector means 10513, and a selector means 10514. The standard exposure video signal 1060 and the non-standard exposure The video signal 1070 is output at the same timing.

Here, the characteristics of the standard exposure video signal 1060 and the non-standard exposure video signal 1070 will be described.

FIG. 3A shows the input / output characteristics of the standard exposure video signal 1060, and FIG.
70 shows input / output characteristics. As can be seen from FIGS. 3A and 3B, since the non-standard exposure video signal 1070 and the standard exposure video signal 1060 have different characteristics of the output of the image sensor with respect to the amount of incident light, the video signal is synthesized by the conventional method. In this case, the characteristics shown in FIG. 11F are obtained, and it is not possible to obtain a composite video signal 1081 having a linear characteristic from a low luminance region to a high luminance region as shown in FIG.

As described above, when the characteristics of the synthesized video signal from the low luminance region to the high luminance region are not linear, false colors are likely to occur. For example, in the case of a three-plate video camera, as shown in FIGS. 12 (R), (G), and (B), the ratio of R, G, and B when the amount of incident light is R: B: G = 10: 1. Even when the video signal is synthesized by the conventional method, the ratio of R, G, and B in the synthesized video signal 1081 synthesized for each of R, G, and B is R: B: G = 7: 1: 1. Will change. Thus, the ratio of R: G: B which should be originally changed may be changed. This causes false colors.

Therefore, in this video signal processing apparatus, in order to prevent the generation of false colors, the standard exposure video signal for each of R, G and B is used.
When the 1060 and the non-standard exposure video signal 1070 are combined, the video signal is processed so that a video signal having linear characteristics from a low luminance region to a high luminance region is obtained. Therefore, the input / output characteristics of the non-standard exposure video signal 1070
The non-standard exposure video signal 1070 is converted so as to have the same input / output characteristics in the 60 non-saturated region, and the converted non-standard exposure video signal 1070 and the standard exposure video signal 1060 are used to perform synthesis.

Therefore, first, the exposure ratio calculating means 11 shown in FIG.
00 calculates the ratio between the signal level at the time of standard exposure and the signal level at the time of non-standard exposure of the exposure time identification signal 1021 (FIG. 2A) input from the image sensor driving means 1020. Then, a gain control signal 1101 indicating a gain at a magnification corresponding to the ratio is output to the gain adjusting means 1110 (FIG. 2B).
, The gain for the video signal at the time of non-standard exposure is set to be larger than the video signal at the time of standard exposure).

The gain adjustment means 1110 for each of R, G and B multiplies the non-standard exposure video signal 1070 by the gain indicated by the gain control signal 1101. As a result, the gain-adjusted video signal 1111 shown in FIG.
Is output.

For example, FIGS. 2A and 2B and FIG.
As shown in (D), the exposure time identification signal 1021 is
(B) Standard exposure video signal 1060 of A / D converter output 1041
(Long) to 64, and the non-standard video signal 1070 (s)
When (hort) is weighted to 2, the gain is controlled so that the non-standard exposure video signal 1070 for each of R, G, and B is multiplied by 32 based on the exposure ratio.

By this gain control, the slopes of the standard exposure video signal 1060 and the non-standard exposure video signal 1070 in each of R, G, and B become equal. The video signal combining means 1080 for each of R, G, and B combines the video signal using the standard exposure video signal 1060 and the non-standard exposure video signal 1111 after the gain adjustment. As a result, the composite video signal 1081 in each of R, G, and B becomes a video signal that maintains linear characteristics from a low luminance region to a high luminance region, as shown in FIG.

Accordingly, as shown in FIGS. 4 (R), 4 (G) and 4 (B), the ratio of R, G and B at the time of the amount of incident light is 10: 1: 1.
Is maintained at 10: 1: 1 even after the synthesis, and is not different from the original ratio of R: G: B at the incident light amount.

Therefore, even if gamma correction and contour correction are performed in the camera process 1090, an image with an excellent high dynamic range without false colors can be obtained from a low luminance region to a high luminance region.

(Second Embodiment) However, if the dynamic range of the display device is limited, the camera process 1090 adjusts the composite video signal 1081 for each of R, G, and B to match the dynamic range of the display device. Need to be clipped.

For example, as shown in FIGS. 8 (R), (G) and (B), when the amount of incident light is R: G: B = 20: 5: 2.
The ratio of R, G, and B, which is 5 when combined by the video signal processing apparatus of the first embodiment, is 20: 5: 25 even after the combination. However, assuming that the limit of the dynamic range of the display device is 20, the video signal is clipped to 20 by the camera process, so that the ratio of R, G, and B is 20: 5: 20, and the R component and the B component are Causes no difference in signal level and causes false color.

The cause of this false color will be described in detail with reference to FIG.

In FIG. 6, RGBMAX means the largest value among the maximum values in the combined R, G, and B frames. Here, RGBMAX is shown as a signal level 25.

DIPSMAX means the dynamic range (upper limit) of the display device. Here, the incident light amount is 2
It is assumed that the dynamic range of the display device is saturated at 0 or more, and DISPMAX = 20.

The saturation level of the standard exposure video signal 1060 is SAT, the synthesis start level of the standard exposure video signal 1060 and the non-standard exposure video signal 1070 is Yth, and the signal level from Yth to SAT is the synthesis width. .

When the incident light amount is 23, the video signal which should be at a signal level like A originally becomes A 'of 20 which is the same signal level as DISPMAX because of the limitation of the dynamic range of the display device. . In other words, in such a case, all signals having a signal level with an incident light amount of 20 or more are regarded as having the same signal level 20 as DISPMAX. (A ′ = DISPMAX) Therefore, depending on the subject, there is no gradation, which causes a false color.

Therefore, in the second embodiment, R,
By applying non-linear processing to the composite video signal 1081 for each of G and B according to the dynamic range of the display device, the gradation and the false color are improved.

As shown in FIG. 5, the apparatus for performing the video signal processing includes a maximum value detecting means 1130 for extracting the largest value among the signal levels of one frame simultaneously output from each of the video signal synthesizing means 1080. And dynamic range setting means 1140 for setting the dynamic range (upper limit) of the display device, and non-linear processing of the composite video signal using the maximum value detected by the maximum value detecting means 1130 and the dynamic range (upper limit) of the display device And a non-linear processing means 1120 for performing the following. Other configurations are the same as those of the first embodiment (FIG. 1).

The R, G, B video signal synthesizing means 1080 of this apparatus detects the maximum value (RMAX, GMAX, BMAX) of the signal level in each one frame and transfers it to the maximum value detecting means 1130. At the same time, the saturation level SAT1082 of the R, G, B standard exposure video signal 1060 is transferred to the non-linear processing means 1120.

The maximum value detecting means 1130 determines the largest value among the maximum values (RMAX, GMAX, BMAX) of the signal level in one frame transferred from the R, G, B video signal synthesizing means 1080 as RGBMAX1131. Extracted as
The data is transferred to the R, G, and B nonlinear processing means 1120. Also,
The dynamic range setting means 1140 of the display device sets the dynamic range (upper limit) of the display device,
The PMAX 1141 is transferred to the R, G, B nonlinear processing means 1120.

As shown in FIG. 6, each of the R, G, and B nonlinear processing means 1120 converts A to A ″ so that the signal level does not saturate even when the incident light amount is 20 or more than the dynamic range of the display device. S = S ″ = RGBMAX = DI
The signal level above SAT is controlled to have non-linear characteristics so as to be SPMAX.

At this time, assuming that the synthesized video signal 1081 is A and A after nonlinear processing is A ", nonlinear processing is not performed when A is below the SAT level, and A = A".

When A is equal to or larger than SAT, in order to realize nonlinear characteristics, αA obtained by internally dividing the difference between RGBMAX and SAT by A is used as a control coefficient, and n is used as a control coefficient of nonlinear characteristics. The following A ″ can be represented by the following equation: RGBMAX−DISPMAX ≧ 0 and A ≧ SAT
In the case of αA = (A-SAT) / (RGBMAX-SAT) A ″ = A − ｛(αA) ⁿ × (RGBMAX−DISPM
AX)｝ RGBMAX-DISPMAX ≧ 0 and A <SAT
In the case of αA = 0 A ″ = A In the case of RGBMAX−DISPMAX <0 αA = 0 A ″ = A

The composite video signal 10 thus nonlinearly processed
6, 81 is shown as the video signal 1121 after the non-linear processing.

This non-linear processing is performed on each of the R, G, and B composite video signals as shown in the following (1) to (3).

(1): Non-linear processing for R component If the synthesized video signal 1081 is R, and R after the non-linear processing is R ", non-linear processing is not performed when R is below the SAT level, so that R = R" (αR = 0).

If R is equal to or larger than SAT, a non-linear characteristic is obtained. If αR obtained by internally dividing the difference between RGBMAX and SAT by R is a control coefficient, and n is a control coefficient of the non-linear characteristic, R ″ after the processing is represented by the following equation: RGBMAX−DISPMAX ≧ 0 and R ≧ SAT
In the case of αR = (R-SAT) / (RGBMAX-SAT) R ″ = R − ｛(αR) ⁿ × (RGBMAX-DISPM
AX)｝ RGBMAX-DISPMAX ≧ 0 and R <SAT
In the case of αR = 0 R ″ = R RGBMAX−DISPMAX <0 αR = 0 R ″ = R

FIG. 7 shows a configuration example of the nonlinear processing means 1120 for the R component when n = 2.

(2) Non-linear processing for G component If the synthesized video signal 1081 is G, and G after the non-linear processing is G ", non-linear processing is not performed when G is below the SAT level, so that G = G" (αG = 0).

If G is equal to or larger than SAT, a non-linear characteristic is obtained. If αG obtained by internally dividing the difference between RGBMAX and SAT by G is used as a control coefficient, and n is a control coefficient of the non-linear characteristic, G ″ after the processing is represented by the following equation: RGBMAX−DISPMAX ≧ 0 and G ≧ SAT
In the case of αG = (G-SAT) / (RGBMAX-SAT) G ″ = G − ｛(αG) ⁿ × (RGBMAX-DISPM
AX)｝ RGBAMAX-DISPMAX ≧ 0 and G <SA
In the case of T αG = 0 G ″ = G In the case of RGBMAX−DISPMAX <0 αG = 0 G ″ = G

(3): Non-Linear Processing for B Component If the synthesized video signal 1081 is B, and B after the non-linear processing is B ", the non-linear processing is not performed when B is below the SAT level, so that B = B" (αB = 0).

If B is equal to or larger than SAT, a non-linear characteristic is obtained. If αB obtained by internally dividing the difference between RGBMAX and SAT by B is used as a control coefficient, and n is a control coefficient of the non-linear characteristic, B ″ after the processing is expressed by the following equation.

The synthesized video signal 1081 is converted to B,
Is B ", the processing represented by the following equation is performed. RGBMAX-DISPMAX ≧ 0 and B ≧ SAT
In the case of αB = (B-SAT) / (RGBMAX-SAT) B ″ = B − ｛(αB) ⁿ × (RGBMAX−DISPM
AX)｝ RGBMAX-DISPMAX ≧ 0 and B <SAT
In the case of αB = 0 B ″ = B RGBMAX−DISPMAX <0 In the case of αB = 0 B ″ = B

FIG. 8 shows how the gradation is improved and the false color is reduced by this non-linear processing.

8 (R), (G) and (B) show the dynamic range of the display device: DISPMAX = 2
Maximum signal level of 0, R, G, B: RGBMAX = 2
5. The case where the non-linear processing is performed on the composite video signal 1081 for each of R, G, and B under the condition that the saturation level of the standard exposure video signal 1060 is SAT = 3.

When the amount of incident light is R: G: B = 20: 5: 25
By performing this non-linear processing, the composite video signal 1081 for each of R, G, and B is R ″: G ″: B ″ = 18: 5:
It will be 20. In the video signal processing of the first embodiment, R,
When the ratio of G and B becomes R: G: B = 20: 5: 20, 20
Although there is no gradation for the above incident light amount, which is a factor of false color, it is improved by this non-linear processing that the gradation higher than DISPMAX is completely destroyed. Since the ratio (hue) of R, G, and B is sufficiently maintained, false colors can be reduced.

The maximum value RGBMAX in one frame
Is always adjusted to the dynamic range DISPMAX of the display device, so that the dynamic range of the display device can be maximized.

Therefore, in this video signal processing device, it is possible to obtain an excellent video signal with less false colors according to the dynamic range of the display device.

[0082]

As is apparent from the above description, the video signal processing apparatus of the present invention can synthesize a video signal having a high dynamic range and maintaining a linear characteristic over a wide range. Can be suppressed.

Even in the case where the dynamic range of the display device is restricted, the generation of false colors can be improved by performing the nonlinear processing on the composite video signal while maximizing the dynamic range of the display device. .

Further, the video signal processing method of the present invention can generate a video signal with a high dynamic range that faithfully reproduces the color of a subject. Since the same hue as that described above can be maintained, a video signal with less false colors can be generated.

Further, the video camera of the present invention can take an image faithful to the hue of the object by overcoming the drawbacks of the solid-state imaging device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a camera system using a video signal processing device according to a first embodiment,

FIG. 2A is a diagram showing characteristics of an exposure time identification signal;
(B) A diagram for explaining the characteristics of the gain control signal.

FIG. 3A is a diagram showing characteristics of a standard exposure video signal;
(B) A diagram showing characteristics of a video signal of non-standard exposure and a gain adjustment of the non-standard exposure video signal, (C) a diagram showing a composite video signal by the video signal processing device of the first embodiment,

FIG. 4 (R) is a diagram showing a composite video signal for an R signal by the video signal processing device of the first embodiment; FIG. 4 (G) is a diagram showing a composite video signal for a G signal by the video signal processing device of the first embodiment; FIG. 1B is a diagram showing a combined video signal for a B signal by the video signal processing device of the first embodiment;

FIG. 5 is a configuration diagram of a camera system using the video signal processing device according to the second embodiment;

FIG. 6 is a diagram showing a combined video signal and a non-linear process which are limited by a dynamic range of a display device;

FIG. 7 is a diagram showing a circuit configuration of a nonlinear processing unit;

FIG. 8 (R) is a diagram showing a composite video signal for an R signal by the video signal processing device of the second embodiment, and FIG. 8 (G) is a diagram showing a composite video signal for a G signal by the video signal processing device of the second embodiment. FIG. 9B is a diagram showing a composite video signal for a B signal by the video signal processing device according to the second embodiment;

FIG. 9 is a diagram showing a camera system using a conventional video signal processing device;

FIG. 10A is a configuration diagram showing a synchronization unit, and FIG.
A diagram showing a D converter output, (C) a diagram showing an output of a memory means, (D) a diagram showing an exposure time identification signal, (E) a diagram showing a non-standard exposure video signal, and (F) a standard exposure video signal. Figure,

11A is a diagram showing characteristics of a standard exposure video signal: LONG, FIG. 11B is a diagram showing characteristics of a non-standard exposure video signal: SHORT, and FIG.
ET1) is a diagram showing characteristics when added, (D) is a diagram showing the synthesis of a standard exposure video signal and a non-standard exposure video signal, (E)
(F) A diagram showing the characteristics of the synthesized video signal,

FIG. 12 (R) is a diagram showing a composite video signal for an R signal by a conventional video signal processing device; FIG. 12 (G) is a diagram showing a composite video signal for a G signal by a conventional video signal processing device;
FIG. 5B is a diagram showing a composite video signal for the B signal by the conventional video signal processing device.

[Explanation of symbols]

 1000 Prism 1010 Image sensor 1020 Image sensor driving means 1021 Exposure time identification signal 1030 Preprocessing means 1040 A / D converter 1041 A / D converter output 1050 Synchronization means 10511 Memory means 10512 Memory output 10513 Selector means 10514 Selector means 1060 Standard Exposure video signal 1070 Non-standard exposure video signal 1080 Video signal synthesis means 1081 Composite video signal 1082 Saturation level 1090 Camera process 1100 Exposure ratio calculation means 1101 Gain control signal 1110 Gain adjustment means 1111 Gain adjusted video signal 1120 Non-linear processing means 1121 Non-linear Video signal after processing 1130 Maximum value detection means 1131 RGBMAX 1140 Dynamic range setting means of display device 1141 DISPMAX

Claims (7)

[Claims] 1. A standard exposure video signal photographed with a standard exposure time and a non-standard exposure video signal photographed with an exposure time shorter than the standard exposure video signal are generated for the same scene. A video signal processing apparatus for synthesizing a video signal having a dynamic range expanded by performing gain adjustment on the non-standard exposure video signal according to an exposure time ratio between the standard exposure video signal and the non-standard exposure video signal. Gain adjusting means; and video signal synthesizing means for generating a high dynamic range synthesized video signal by synthesizing the standard exposure video signal and the gain-adjusted non-standard exposure video signal according to a signal level. A video signal processing device. 2. The standard exposure video signal and the non-standard exposure video signal are generated for each of R, G, and B obtained by separating incident light, and the gain adjustment unit performs the non-standard exposure for each of R, G, and B. 2. The video signal processing apparatus according to claim 1, wherein gain adjustment is performed on the video signal, and the video signal synthesizing unit generates a synthesized video signal for each of R, G, and B. 3. The apparatus according to claim 1, further comprising a non-linear processing unit that performs non-linear processing on the synthesized video signal generated by the video signal synthesizing unit in accordance with a dynamic range of a display device. The video signal processing device according to the above. 4. A standard exposure video signal captured with a standard exposure time and a non-standard exposure video signal captured with an exposure time shorter than the standard exposure video signal are generated for the same scene.
A video signal processing method for synthesizing a video signal whose dynamic range has been expanded by using them, according to an exposure time ratio between the standard exposure video signal and the non-standard exposure video signal, a gain for the non-standard exposure video signal. A video signal processing method for generating a high dynamic range composite video signal by combining the standard exposure video signal and the non-standard exposure video signal whose gain has been adjusted according to the signal level. . 5. The method according to claim 4, wherein the steps from the generation of the standard exposure video signal and the non-standard exposure video signal to the generation of the composite video signal are performed for each of R, G, and B obtained by separating incident light. The video signal processing method according to the above. 6. The video signal processing method according to claim 4, wherein the synthesized video signal is subjected to non-linear processing according to a dynamic range of a display device. 7. A video signal processing apparatus according to claim 1, further comprising an image sensor as a photographing means, and a video signal processing apparatus according to claim 1 for processing a video signal photographed by said photographing means. A video camera characterized by the following.