JP4423770B2 - Housing for camera characteristic evaluation, camera characteristic evaluation method, and camera characteristic evaluation apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera characteristic evaluation housing, a camera characteristic evaluation method, and a camera characteristic evaluation apparatus. Specifically, when evaluating camera characteristics such as a video camera with a wide dynamic range with respect to the amount of subject light, it is possible to simultaneously image a subject for camera characteristic evaluation using light from two light sources having different illuminance and color temperature. By doing so, the camera characteristics of a video camera with a wide dynamic range can be accurately evaluated.
[0002]
[Prior art]
In an imaging device such as a video camera, it is necessary to capture the subject under the best imaging conditions. Therefore, including the white balance of the video camera to be used in advance, the dynamic range for the subject light amount, gradation reproducibility, etc. It is necessary to know various imaging characteristics (camera characteristics).
[0003]
In order to achieve such an object, a camera characteristic evaluation apparatus has been conventionally used. FIG. 11 is a specific example of the camera characteristic evaluation apparatus 1 and includes a camera characteristic evaluation housing 10, a camera 12 to be measured, and measurement means 14.
[0004]
The camera characteristic evaluation housing 10 has a subject 18 mounted on the front surface of the case body, and a light source 16 is housed therein. The subject 18 projected by the light source 16 is imaged by the camera 12 to be measured. .
[0005]
The picked-up output signal is supplied to the measuring device 14, various camera characteristics are measured and evaluated, and adjustment processing for the camera under measurement 12 is performed as necessary. Among the camera characteristics, the characteristics to be evaluated include white balance, dynamic range, gradation reproducibility, color reproducibility, and the like as described above.
[0006]
As the camera characteristic evaluation subject 18, for example, a gray scale plate whose gradation changes sequentially as shown in FIG. 12 is used. Using a gray scale plate, white balance, dynamic range, gradation reproducibility, etc. can be evaluated. When evaluating color reproducibility, a color bar plate or the like is used instead of the gray scale plate.
[0007]
As the camera 12 to be measured, in addition to a video camera having a normal dynamic range, a video camera having a wider dynamic range that can handle a light amount in a wider range than a normal light amount can be used. Here, a video camera having a wide dynamic range is called a video camera for a wide dynamic range (WDR).
[0008]
This wide dynamic range video camera is already known (Japanese Patent Laid-Open Nos. 6-153089, 7-177427, 6-269209, etc.). This type of video camera, for example, enables a person in the room to capture an image of the outside of a window from outside so as not to be blacked out, and to prevent an outdoor landscape or person from being shot out of white. It was developed.
[0009]
For this purpose, the dynamic range that can be handled with respect to the amount of light of the subject needs to be expanded (widened). There are various methods for widening the dynamic range, and one method is generally to image twice for the same field.
[0010]
In this case, for the same image frame (imaging area), in the first half field, for example, the first imaging signal is obtained by lowering the shutter speed. In the latter half of the field, the second imaging signal is obtained by increasing the shutter speed and imaging. Imaging when the shutter speed is slow (normal shutter speed) is mainly for imaging low-illuminance subjects (for example, indoor subjects) in the same image frame. I can image. On the other hand, imaging when the shutter speed is high is mainly for imaging a high-illumination subject (for example, an outdoor subject). Since the shutter speed is fast, the subject can be captured without being overexposed even if it is a bright subject. .
[0011]
These first and second imaging signals are appropriately combined and output as one imaging signal, and the combined imaging signal is used as a signal of a wide dynamic range video camera.
[0012]
[Problems to be solved by the invention]
By the way, when a video camera with a wide dynamic range as described above is used as a camera to be measured instead of a video camera having a normal dynamic range, the conventional camera characteristic evaluation apparatus cannot accurately evaluate the camera characteristic. found. This is based on the following reasons.
[0013]
First, a problem occurs when, for example, white balance is evaluated or adjusted using the conventional camera characteristic evaluation apparatus 1. This is because the conventional apparatus uses a single light source 16 as shown in FIG.
[0014]
In a wide dynamic range video camera, two subjects with different illuminance and color temperature must be imaged, such as indoors and outdoors. Therefore, when the single light source 16 is used, it must be used while adjusting the illuminance or replacing the color temperature conversion filter (ND filter). Therefore, the white balance cannot be accurately evaluated or adjusted due to misadjustment of illuminance or variations in the characteristics of the color temperature conversion filter.
[0015]
In particular, since the white balance that is actually used is a signal after the first and second imaging signals are combined, there is no means for evaluating and adjusting the white balance for the combined imaging signal. For this reason, the conventional apparatus cannot accurately measure the white balance characteristic of the wide dynamic range, and as a result, the white balance is not sufficiently adjusted.
[0016]
Regarding gradation reproducibility and the like, since there is only one gray scale, a video camera that can handle even a light amount exceeding the light amount range that can be measured with this gray scale cannot be evaluated.
[0017]
Therefore, the present invention solves such a conventional problem, and proposes a camera characteristic evaluation apparatus and the like that can accurately evaluate a camera characteristic particularly at the time of imaging with different illuminance and color temperature. is there.
[0018]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, in the camera characteristic evaluation housing according to the present invention described in claim 1,It has the 1st division room and the 2nd division room which were shieldedCase bodyAnd accommodated in the first division chamberWith a first light source, Housed in the second divided chamber, and different in illuminance and color temperature from the first light source.2 light sourcesAnd aboveRecordFirst and secondLight sourceeachOn the light pathAttached,Camera characteristics evaluation subject imaged by the camera under measurementThe camera characteristic evaluation subject is configured to be detachable from the case body.
[0019]
  Claim6In the camera characteristic evaluation apparatus according to the present invention described in 1.It has the 1st division room and the 2nd division room which were shieldedCase bodyAnd accommodated in the first division chamberWith a first light source, Housed in the second divided chamber and different in illuminance and color temperature from the first light sourceSecond light sourceAnd the first and second light sourcesOn each light pathAttachedSubject for camera characteristics evaluationAnd havingA camera characteristic evaluation case;The camera characteristics evaluation housingA camera to be measured for imaging the subject for camera characteristic evaluation;the aboveMeasuring means for measuring camera characteristics from the output signal of the camera under measurement;The camera characteristic evaluation subject of the camera characteristic evaluation case is configured to be detachable from the case body.
[0020]
  Claim8In the camera characteristic evaluation method according to the present invention described in 1), a case is used in which two light sources having different illuminance and color temperature are housed in the case body, and a camera characteristic evaluation subject is mounted on the front surface thereof. In the camera characteristic evaluation method for evaluating the camera characteristics of the camera to be measured, when a camera having a wide dynamic range with respect to the amount of light of the subject is used as the camera to be measured, and white balance is evaluated as the camera characteristics. An output signal obtained when the camera characteristic evaluation subject is imaged using the first light source and an output obtained when the camera characteristic evaluation subject is imaged using the second light source Signal andThe white balance is adjusted by adjusting so that the bright spots of the two output signals coincide with each other.
[0021]
  Claim10In the camera characteristic evaluation method according to the present invention described in 1), a case is used in which two light sources having different illuminance and color temperature are housed in the case body, and a camera characteristic evaluation subject is mounted on the front surface thereof. In the camera characteristic evaluation method for evaluating the camera characteristics of the camera to be measured, when a camera having a wide dynamic range with respect to the light amount of the subject is used as the camera to be measured, and the dynamic range is evaluated as the camera characteristics. A gray scale plate is used as the object for camera characteristic evaluation, and the desired scale of one of the gray scales is set as the reference illuminance, and the dynamic range is measured based on the reference gray scale.It is a thing.
[0022]
In the present invention, at least two types of light sources having different illuminance and color temperature are used as light sources for irradiating the measurement subject. These light sources are shielded from each other. And it images with the to-be-measured camera through the object irradiated by those light sources. As the subject, a colorless transparent plate (clear sheet plate), a gray scale plate, a color bar plate, or the like is used.
[0023]
Two gray scales having the same pattern are printed on the gray scale plate. Therefore, when the gray scale plate is used as a subject, the first gray scale (upper gray scale) illuminated by the first light source used for high illuminance is imaged to obtain a first imaging signal. A second image signal is obtained by capturing an image of the second gray scale irradiated with a second light source having a color temperature different from that of the first light source used for illuminance.
[0024]
The white balance is measured and evaluated using the first imaging signal, and when it is different from the reference, the white balance at high illuminance is adjusted by adjusting. Similarly, the white balance is measured and evaluated using the second imaging signal, and when this is different from the reference, the output stage of the camera is adjusted to adjust the white balance at low illuminance.
[0025]
Then, the white balance by the imaging signal when the first imaging signal and the second imaging signal are combined is measured and evaluated. As a result, the white balance in the wide dynamic range is adjusted when it is different from the reference. Thus, even with a wide dynamic range video camera, if the first and second imaging signals obtained simultaneously are used, the white balance in the wide dynamic range can be accurately evaluated and adjusted correctly. it can.
[0026]
Next, when evaluating the wide dynamic range, for example, when the measurement is based on the second gray scale, and the amount of light exceeding the gray scale range can be handled, the evaluation is performed using the first gray scale. . At this time, since the illuminance difference between the first and second light sources is known in advance, the wide dynamic range of the camera can be measured from the first and second gray scales by taking this illuminance difference into account. Therefore, the wide dynamic range can be accurately evaluated.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Subsequently, an embodiment of a camera characteristic evaluation housing, a camera characteristic evaluation apparatus, and a camera characteristic evaluation method according to the present invention will be described in detail with reference to the drawings.
[0028]
For convenience of explanation, the camera characteristic evaluation apparatus will be described. FIG. 1 shows an embodiment of a camera characteristic evaluation apparatus 1 according to the present invention. The structure is almost the same as that of the prior art except for a camera characteristic evaluation case. Therefore, the camera characteristic evaluation housing 10, the camera to be measured 12, and the measurement unit 14 are configured. The measurement unit 14 uses an operation unit 19 using a keyboard or the like for inputting a measurement type. The measuring means 14 uses a vector scope or an oscilloscope depending on which camera characteristics are mainly measured and evaluated.
[0029]
The camera characteristic evaluation casing 10 is configured as shown in FIG.
In FIG. 2, a case main body 22 having a substantially rectangular shape is provided. The case main body 22 is divided into two upper and lower stages by a shielding plate 24 provided at an intermediate portion, and the first division chamber 26a located at the upper stage includes The first light source 28 is accommodated, and the second light source 29 is accommodated in the second divided chamber 26b located at the lower stage. As the light sources 28 and 29, light sources having different illuminance and color temperature are used. This is because the illuminance and the color temperature are different when taking images indoors and outdoors.
[0030]
In the embodiment, the first light source 28 is a light source close to natural light, that is, a light source with high illuminance. Therefore, a xenon lamp, a white light bulb, or the like is used as the first light source 28. In the figure, a xenon lamp is used. On the other hand, a low illuminance light source is used as the second light source 29. A light source (fluorescent lamp) corresponding to an indoor illumination light source is used.
[0031]
Windows 30a and 30b corresponding to the respective divided chambers 26a and 26b are formed on the front surface of the case body 22, and a camera characteristic evaluation subject (hereinafter referred to as a subject) 18 is detachable so as to cover the windows 30a and 30b. Installed. Therefore, a guide plate 32 having an L-shaped cross section that functions as a mounting guide is provided.
[0032]
An embodiment of the subject 18 will be described with reference to FIG. In this embodiment, as shown in the figure, the subject 18 is configured by providing colorless and transparent plates 18b and 18c on both sides so as to sandwich a flat subject body 18a. As described above, the subject body 18a is a gray scale plate (chart) or a color bar plate (chart). Thus, in the sandwich structure using the colorless and transparent plates 18b and 18c, the colorless and transparent plate (clear chart) used at the time of white balance evaluation is unnecessary. This is because the colorless transparent plates 18b and 18c can be substituted.
[0033]
FIG. 4 shows an example of the gray scale plate 34 as the subject main body 18a. In this embodiment, a transparent acrylic plate or glass plate is used, and a white window 36 that can be used for white level adjustment is provided on the surface of the transparent acrylic plate or glass plate. First and second gray scales 38a and 38b are formed at predetermined positions.
[0034]
That is, the first gray scale 38a and the upper half of the white area 36 are located at a position corresponding to the transmission window 30a, and the second gray scale 38b and the lower half of the white area 36 are located at a position corresponding to the transmission window 30b. Is formed to be positioned.
[0035]
The gray scales 38a and 38b are arranged such that a plurality of scales (charts) whose densities are sequentially changed so that the emitted illuminance changes in a stepwise manner at a constant rate, are gradually darkened from white and finally become black. In this embodiment, one gray scale is configured with a scale of 10 stages. The gradient of density change is arbitrary, but in this example, when white is used as a reference (1 × = × 1), the adjacent scale is selected so that its brightness is ½ that of the white scale. The density at that time is displayed as “× 2”. Incidentally, in this embodiment,
"X1, x2, x4, x8, x12, x16, x24, x32, x48, x64"
In this case, “× 64” is all black.
[0036]
The first gray scale 38a and the second gray scale 38b have exactly the same configuration, the same change direction of the density gradient, and the density increases from left to right.
[0037]
As described above, the gray scale having the same scale configuration is arranged in two upper and lower stages. When the luminance level of the signal when the image is picked up is monitored, it is displayed in the same manner with the difference in illuminance between the upper and lower stages. This is because the level comparison between the two becomes easy.
[0038]
Next, an embodiment of the camera 12 to be measured will be described with reference to FIG. As the camera to be measured, a wide dynamic range video camera (color camera) is exemplified as described above.
[0039]
The subject 18 is guided to the image sensor 42 via the optical lens 40, and the subject image is converted into an electrical signal (imaging signal). A semiconductor image sensor such as a CCD can be used as the image sensor 42. The imaging format of the imaging element 42 may be a single plate type or a three plate type.
[0040]
The imaging signal is supplied to the previous value signal processing unit 44. First, a correlated double sampling (CDS) circuit 44a performs correlated double sampling, correlated double sampling, and a waveform-shaped image signal is subjected to gain adjustment processing by the next automatic gain adjustment (AGC) circuit 44b. Done.
[0041]
In this embodiment, white balance adjustment is also performed in the three AGC circuits 44b provided corresponding to the channels of the imaging signals corresponding to the R, G, and B primary colors. Further, the preceding value signal processing unit 44 is provided with an A / D converter 33c, and the image signal subjected to white balance adjustment is converted into a digital signal by the A / D conversion means.
[0042]
The digitally converted image pickup signal is further converted by the main signal processing unit 46 into a desired video signal, for example, a video signal composed of a luminance signal Y and a pair of color signals Cr and Cb. Accordingly, the main signal processing unit 46 uses a DSP (Digital Signal Processor) circuit or the like.
[0043]
The output from the main signal processing unit 46 is used as a normal camera output. This video signal is further supplied to a control unit 48 formed of a computer, and a control signal is given to the driver 50 to adjust the diaphragm of the optical lens system 40 in this example. Further, the shutter speed and field frequency for the CCD 42 are instructed from the control unit 48, and a white balance adjustment signal and the like are supplied to the preceding value signal processing unit 44.
[0044]
Here, as described above, the operator can switch whether to use the dynamic range as a normal range or a wider range. The terminal 48a is a control signal input terminal, and functions as a key signal input terminal from an operation unit provided in the camera body.
[0045]
When the shutter speed when using the standard dynamic range is the shutter speed for low illuminance, the shutter speed is switched to the shutter speed for high illuminance (high shutter speed) in the wide dynamic range mode. The speed ratio is 2-4 times. In addition, in the wide dynamic range mode, imaging is performed twice in one field.
[0046]
In the first half field, for example, the subject is imaged at the shutter speed for high illuminance to obtain the first imaging signal, and in the second half field, for example, the subject is captured at the shutter speed for low illuminance. A second imaging signal is acquired by imaging. The first and second imaging signals are synthesized at a certain ratio, and the above-described video signal is purified from the synthesized imaging signal.
[0047]
As described above, in the wide dynamic range mode, an imaging process of switching the field scanning frequency or alternately switching the shutter speed is performed, and a control signal for that purpose is generated by the control unit 48.
[0048]
As the measurement means 14 shown in FIG. 1, a vector scope, an oscilloscope, or the like is used as described above. When measuring, evaluating and adjusting the white balance, a vector scope is used, and the white level of the bright spot displayed on the monitor (the bright spot on the coordinate axis by the RY and BY axes) is white. Balance is measured, evaluated and adjusted.
[0049]
Subsequently, a camera characteristic evaluation method according to the present invention using the present invention will be described with reference to FIG.
(1) White balance evaluation
As the subject 18, an entirely colorless transparent plate or a gray scale plate 34 may be used. In the case of a standard dynamic range video camera, a second light source 28 is used. In the case of a wide dynamic range video camera, both the first and second light sources 28 and 29 are used simultaneously. As the measuring means 14, a vector scope (vector scope) is used.
[0050]
As in the flowchart of FIG. 6, in the case of white balance evaluation, the image frame of the camera is aligned with the light source surface of the housing 10 (shown by the chain line in FIG. 4) (step 61) and then switched to the white balance WB mode ( Step 62). This is because the light source used and the processing steps of the imaging signal are different depending on whether the video camera has only the standard dynamic range or the wide dynamic range.
[0051]
Next, in this state, the mounted gray scale plate 34 is used in this example, and this is imaged by the video camera 12. Then, white balance is measured and evaluated using the obtained imaging signal (video signal) (step 63).
[0052]
The white balance evaluation items include whether the position of the bright spot of the white balance (the convergence point when the automatic white balance mode is activated) is in the normal position, whether the white balance is correct, and the bright spot. The time until the convergence to the convergence point is measured.
[0053]
If the white balance matches the reference, there is no problem, but when it is deviated (step 64), gain adjustment (R: G: B = 1: 1: 1) is performed using the AGC circuit 44b (step 65). ) Evaluation is performed again using the image signal after adjustment. With such repetition, the white balance measurement, evaluation and adjustment are completed.
[0054]
Here, when evaluating a wide dynamic range video camera, the following processing is performed. As described above, in a video camera for a wide dynamic range, white balance needs to be adjusted regardless of whether the video camera is used indoors or outdoors. In addition to this, white balance must be maintained even in the wide dynamic range mode.
[0055]
First, when used separately indoors and outdoors, a white level bright spot (white level convergence point) is displayed by the second imaging signal obtained from the low illuminance side. When the gray scale plate 34 is used, the evaluation is performed using an imaging signal obtained from the white scale “× 1”.
[0056]
When the bright point (second bright point) at that time is not deviated from the reference point (standard point), it is treated as being correctly adjusted. When the position is deviated from the reference point, the second bright spot is adjusted. When this adjustment is completed, the white balance adjustment at the time of low illuminance is completed as in indoor imaging. The convergence speed to the second bright spot is also an evaluation target.
[0057]
Similarly, white level bright spots (first bright spots) are displayed based on the first imaging signal obtained from the high illuminance side, and the white balance is evaluated from the deviation from the reference point. When it is deviated from the reference point, the same adjustment is performed to match the reference point. As a result, it is possible to obtain an imaging signal with white balance even when imaging is performed outdoors.
[0058]
Next, in the wide dynamic range mode in which both indoor and outdoor subjects are imaged, as described above, image capturing is attempted twice in one field, and the main signal processing unit 46 performs signal synthesis processing. Then, the synthesized video signal is supplied to the vector scope 14 and white level bright spots are displayed. In this mode, when there are two bright spots, adjustment in the previous value signal processing unit 44 is performed so that there is one bright spot. This completes the white balance evaluation and adjustment processing in the wide dynamic range mode.
[0059]
(2) Evaluation of color reproducibility
When evaluating the color reproducibility, a waveform monitor is used as the measuring means 14 and a color bar plate is used as the subject 18. As the color pattern of the color bar plate, for example, a color bar pattern conforming to the Japan Electronics Machinery Association (EIAJ) standard can be used. In the case of color reproducibility, any one of the light sources 28 or 29 (for example, the light source 28) may be used.
[0060]
In the flowchart shown in FIG. 7, a color bar plate is selected as the subject (step 71), and then the imaging area is adjusted so that the color bar plate fills the image frame of the camera 12 (step 72). Next, it is selected whether the white balance mode is the standard dynamic range mode or the wide dynamic range mode (step 73).
[0061]
After a sufficient white balance pull-in time has elapsed, the color reproducibility is evaluated using a monitor (step 74). In other words, it is evaluated whether the hue and saturation are correctly adjusted. If adjustment is necessary as a result of the evaluation, necessary adjustment of the camera 12 is adjusted (steps 75 and 76). By performing this adjustment, the color reproducibility process ends.
[0062]
(3) Dynamic range evaluation
For example, when the video camera to be evaluated is a wide dynamic range video camera, first, the image frame of the camera is used as the subject 18 in the state where the gray scale plate 34 shown in FIG. (Steps 81 and 82).
[0063]
Next, the brightness level is adjusted in a state in which the wide dynamic range mode is turned off, that is, in a mode in which the standard dynamic range is set (step 83). The brightness level adjustment is based on the lower gray scale (for low brightness) 38b. The video camera 12 has a brightness of 100% white (= 100 IRE (Institute of Radio Engineers)) when an appropriate scale of the gray scale 38b, for example, a scale of “× 64” is imaged. Is adjusted (step 84). When the adjustment is completed, the wide dynamic range mode is turned on (step 85).
[0064]
The gray scale board 18 is imaged with the wide dynamic range mode turned on, and the brightness level of the second gray scale 38b located at the lower stage is evaluated using a monitor or an oscilloscope (step 86). Then, it is determined whether or not the brightest scale (“× 1” scale) of the low-brightness gray scale 38b can be observed without whiteout (step 87).
[0065]
If the scale of “× 1” can be observed normally, it can be seen that at least the dynamic range of the video camera 12 has 64 times the performance of the reference light amount. Accordingly, in this case, the scale of the upper gray scale 38a used for high luminance is observed to calculate the dynamic range, and the evaluation process is terminated (step 88).
[0066]
Here, when the illuminance ratio between the first light source 28 and the second light source 29 is, for example, 30 times, among the scales of the first gray scale 38a, the fifth stage from the white reference side (“× 12 ”Scale), and after that the gradation level cannot be determined from the white scale and the brightness level is saturated.
(64/12) x 30 times = 160 times
It can be seen that the dynamic range has been expanded.
[0067]
When the camera to be evaluated has a standard dynamic range, the evaluation is performed using only the lower gray scale 38b. The dynamic range is evaluated by the width (number of scales) to the discriminable scale. For example, when the level of the imaging signal obtained from the “× 1” scale is adjusted to 100 IRE and the gradation can be distinguished from the “× 1” scale to the “× 32” scale, the dynamic range at that time is Judged to be 32 times. Normally, the dynamic range is set so that it can be discriminated up to “× 64”.
[0068]
(4) Evaluation of gradation reproducibility
When the gamma characteristic of the video camera 12 to be evaluated is turned off, whether the gradation difference between the gray scales is as designed or whether the gradation difference is constant over the entire scale. The gradation reproducibility of the video camera 12 is evaluated depending on whether all gradations of the gray scale can be recognized. As the evaluation equipment (measuring means 14), a waveform monitor, an oscilloscope or the like can be used.
[0069]
In the case of tone reproducibility evaluation, a gray scale plate 34 as shown in FIG. 4 is mounted as shown in FIG. 9, and image frame adjustment of the video camera is performed (steps 91 and 92). When the image frame adjustment is completed, with the wide dynamic range mode turned off, the brightness level is adjusted so that the white level obtained from the “× 1” scale in the lower gray scale 38a is, for example, 100 IRE. Steps 93, 94).
[0070]
When the adjustment of the brightness level is completed, the wide dynamic range mode is turned back on (step 95). In this state, first, the gradation in the low luminance region, that is, the low illuminance region is evaluated using the luminance signal from the lower gray scale 38b (step 96). The gradation evaluation is performed by the method as described above.
[0071]
Similarly, using the luminance signal from the upper gray scale 38a, the gradation in the high luminance region, that is, the high illuminance region is evaluated using the same method as described above. Then, it is determined whether or not the desired performance is obtained. When it is determined that the performance is insufficient, the design value is reviewed, or the video camera 12 is readjusted depending on the case and the readjustment is performed. The same tone reproducibility is evaluated again (steps 97, 9, 93).
[0072]
In the above-described embodiment, white balance, dynamic range, gradation reproducibility, and color reproducibility are exemplified as camera characteristics. However, camera characteristics other than these can be evaluated according to the purpose.
[0073]
【The invention's effect】
As described above, according to the present invention, at least two types of light sources having different illuminance and color temperature are used as light sources for irradiating the subject to be measured. The present invention proposes a camera characteristic evaluation housing, an evaluation apparatus, and an evaluation method that can be simultaneously imaged.
[0074]
According to this, camera characteristics (white balance, dynamic range, color reproducibility, gradation reproducibility, etc.) such as a video camera with a wide dynamic range with respect to the amount of subject light can be obtained from two light sources with different illuminance and color temperature. Since it can be evaluated simultaneously using light, it has the feature that the camera characteristics can be accurately evaluated even for a video camera with a wide dynamic range, which often captures indoor and outdoor subjects simultaneously.
[Brief description of the drawings]
FIG. 1 is a system diagram of a main part showing an embodiment of a camera characteristic evaluation apparatus according to the present invention.
FIG. 2 is a cross-sectional view showing an embodiment of a camera characteristic evaluation casing.
FIG. 3 is a cross-sectional view showing an example of a subject for camera characteristic evaluation.
FIG. 4 is a plan view showing an embodiment of a gray scale plate.
FIG. 5 is a system diagram of a video camera to be measured.
FIG. 6 is a flowchart illustrating a processing example when white balance is evaluated.
FIG. 7 is a flowchart illustrating a processing example when evaluating color reproducibility.
FIG. 8 is a flowchart showing an example of processing when evaluating a dynamic range.
FIG. 9 is a flowchart illustrating a processing example when evaluating gradation reproducibility.
FIG. 10 is a configuration diagram of a conventional camera characteristic evaluation apparatus.
FIG. 11 is a gray scale plate used at that time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Camera characteristic evaluation apparatus, 10 ... Camera characteristic evaluation housing | casing, 12 ... Camera for to-be-measured, 14 ... Measuring means, 18 ... Subject, 22 ... Main body, 26a, 26b ... division chamber, 28, 29 ... light source, 34 ... gray scale plate, 38a, 38b ... gray scale, 44 ... pre-value signal processing unit, 46 ... main signal processing unit

Claims (11)

A case body having a shielded first division chamber and a second division chamber ;
A first light source housed in the first divided chamber ;
A second light source housed in the second divided chamber and having a different illuminance and color temperature from the first light source ;
Upper Symbol attached to the respective optical paths of the first and second light sources, and a camera characteristic evaluation subject photographed by the measuring camera,
The camera characteristic evaluation subject, detachably constructed camera characterization casing relative to the case body. Examples of the first light source, is used a light source close to natural light, the camera characteristic evaluation housing of 請 Motomeko 1, wherein the indoor illumination light source is used as the second light source. When using the grayscale plate as the camera for evaluating characteristics the photographic body, the camera characterization housing of the respective 請 Motomeko 1, wherein the gray scale of each the same configuration on the opposite portion is formed on the light source . A pair of gray scale formed on the gray scale plate are the same, the camera characterization housing of the concentration change direction 請 Motomeko 3 wherein is selected in the same direction. When using the color bar plate as the camera characteristic evaluation subject, the formed color bars plate pattern, two formed請 Motomeko 1, wherein the camera to be used in common to the light source Characteristic enclosure. A case main body having a shielded first division chamber and a second division chamber, a first light source accommodated in the first division chamber, and a first light source accommodated in the second division chamber, and the first division chamber. A camera characteristic evaluation housing having a second light source having a different illuminance and color temperature, and a camera characteristic evaluation subject mounted on the optical path of each of the first and second light sources ,
A camera to be measured for capturing an image of the camera characteristic evaluation subject in the camera characteristic evaluation case;
And a measuring means for measuring a camera characteristic from an output signal of the camera under test,
The camera characteristic evaluation subject of the camera characterization housing is detachably configured camera characteristic evaluation apparatus relative to the case body. The measuring camera is a camera characteristic evaluation apparatus 請 Motomeko 6 wherein Ru video camera der which the dynamic range has been expanded to handle the subject light intensity. Evaluate the camera characteristics of the camera to be measured by using a camera characteristic evaluation housing in which two light sources with different illuminance and color temperature are housed in the case body, and a camera characteristic evaluation subject is attached to the front of the light source. In the camera characteristic evaluation method,
When using a camera with a wide dynamic range for the subject light amount as the camera to be measured and evaluating white balance as its camera characteristics,
An output signal obtained when the camera characteristic evaluation subject is imaged using the first light source, and an output signal obtained when the camera characteristic evaluation subject is imaged using the second light source two bright points of the output signal is adjusted to be such to match, camera characteristic evaluation method to perform the adjustment of the white balance with. Above when the evaluation of white balance, the examples of camera characterization for an object, 請 Motomeko 8 camera characteristic evaluation method according to colorless, transparent plate or grayscale plate Ru is used. Evaluate the camera characteristics of the camera to be measured by using a camera characteristic evaluation housing in which two light sources with different illuminance and color temperature are housed in the case body, and a camera characteristic evaluation subject is attached to the front of the light source. In the camera characteristic evaluation method,
When using a camera with a wide dynamic range for the subject light amount as the camera to be measured, and when evaluating the dynamic range as its camera characteristics,
A gray scale board is used as the subject for camera characteristic evaluation, and a desired scale of one gray scale is set as a reference illuminance,
Camera characterization methods to measure the dynamic range of the reference gray-scale reference. 請 Motomeko 10 camera characteristic evaluation method according which to perform the evaluation of the wide dynamic range by utilizing each of the pair of gray scale formed on the camera characteristic evaluation object.

Images