JP3871681B2 - Imaging apparatus and camera - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus capable of correcting a specific color according to preference, and a camera including such an imaging apparatus.

  For an imaging apparatus, the skin color is a memory color like plants and sky, and its color reproducibility is important, and many methods for correcting the skin color have been proposed so far. For example, a technique for manually inputting a skin color area or information about the color (saturation (or saturation), hue) on a device that performs image quality editing of an image, and performing color correction on a target correction color or correction area Has been proposed (for example, Patent Document 1 and Patent Document 2).

  In addition, a technique has been proposed in which a skin color region is detected by comparing a ratio or difference between a luminance signal and a color difference signal with a threshold value, and a color in the region is corrected (for example, Patent Document 3).

  In general, Japanese women prefer that their skin is white, so many cosmetics are sold that make the skin color appear white (hereinafter referred to as whitening), and the color is more common than the original skin color. Furthermore, since the spectral reflectance is high from 400 nm to 700 nm, the color appears white (for example, Patent Document 4). In the signal processing, the same effect can be obtained by reducing the color saturation of the skin color region or increasing the luminance value.

On the other hand, particularly in the case of men, it may be desired that the skin color is tanned. A tanned skin color has a lower spectral reflectance at 400 to 700 nm than the original skin color, and the color looks black (for example, Patent Document 4). For this reason, a technique for obtaining the same effect can be improved by signal processing for increasing the color saturation of the skin color region or decreasing the luminance value.
JP 2003-234916 A JP 2000-261650 A JP 2000-217127 A JP 2001-74556 A

  However, the techniques described in Patent Document 1 and Patent Document 2 are capable of flexible and good color reproducibility processing, but have a problem that the work is complicated and requires complicated processing. Further, since the correction is performed after the imaging is completed, there is a problem that the simultaneousness of checking simultaneously while imaging is lacking.

  In addition, with the technique described in Patent Document 3, high detection accuracy cannot be desired in an imaging apparatus that captures images under various illumination light sources using only RGB values and YCrCb threshold values. Furthermore, since color correction is performed only on the detection area, there is a problem that the boundary of the area becomes unnatural. Furthermore, since a separate detection means is required, there has been a problem that the circuit scale of the imaging apparatus becomes large.

  Furthermore, if you increase or decrease the saturation by focusing on the skin color area, there is a problem that the saturation of the entire image changes and it becomes unnatural. If you want to correct only the skin color, As described above, there is a problem that a means for detecting the skin color portion is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an imaging device that can correct a specific color without requiring complicated and complicated input.

The imaging apparatus of the present invention
In an imaging device capable of correcting a specific color,
Color signal generating means for receiving incident light, separating the incident light into at least three color components, and outputting color signals corresponding to the at least three color components;
A luminance color difference signal generating means for receiving the color signal and generating a luminance signal and a color difference signal;
A luminance signal gradation conversion means for receiving the luminance signal output from the luminance color difference signal generation means and performing gradation conversion;
A color difference signal gradation conversion means for receiving the color difference signal output from the luminance color difference signal generation means and performing gradation conversion;
Gain adjusting means for receiving the output of the color difference signal gradation converting means, amplifying it with an adjustable gain, and outputting it;
The luminance signal gradation conversion means changes the output signal when the change amount of the output signal in the level range of the luminance signal input to the luminance signal gradation conversion means is outside the level range when the correction target color is imaged. The input / output characteristics can be changed to be larger than the quantity,
The chrominance signal gradation converting means changes the output signal when the change amount of the output signal in the level range of the chrominance signal input to the chrominance signal gradation converting means is outside the level range when the correction target color is imaged. The input / output characteristics can be changed to be larger than the quantity,
When the color difference signal gradation converting means changes its input / output characteristics, the gain adjusting means changes the output signal of the color difference signal gradation converting means due to the change of the input / output characteristics in the color difference signal gradation converting means. The gain is adjusted so that the output signal changes in the opposite direction.

  According to the present invention, it is possible to easily perform desired color correction without requiring manual color correction work, and for example, it is possible to easily obtain skin whitening or tanned skin color.

  In addition, since the influence on the color reproducibility of other images due to the correction of the color to be corrected, for example, the skin color, can be reduced, and no detection means for detecting the skin color is required, so the configuration of the imaging device can be simplified. can do.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram showing an imaging apparatus according to Embodiment 1 of the present invention.
As shown in the figure, this imaging apparatus includes an imaging means 1, a white balance means (WB) 3, a luminance / color difference signal generation means 4, a luminance signal gradation conversion means 5, a color difference signal gradation conversion means 6, and a gain. An adjustment unit 7, an imaging mode control unit 8, and an imaging mode selection unit 9 are included.

The color signal generating means 1 receives incident light, separates the incident light into at least three color components, and outputs color signals corresponding to the at least three color components. For example, as shown in FIG. ,
The imaging unit 11, the amplification unit 12, an A / D converter (ADC) 13, and a direct current component reproduction unit (DC reproduction unit) 14 are included.
For example, as shown in FIGS. 3A and 3B, the image pickup means 11 includes an optical system 21 including a lens, an image pickup element 22 having a plurality of photoelectric conversion elements arranged two-dimensionally, and a color separation means. As a color filter 23.
The plurality of photoelectric conversion elements of the image sensor 22 correspond to the three primary colors of red (R), green (G), and blue (B), which are arranged in a Bayer type as shown in FIG. 3A, for example. It is covered with a color filter 23 having a spectral transmittance.

  Light incident from the optical system 21 forms an image on the light receiving surface of the image sensor 22. The image sensor 22 is covered with the color filter 23 as described above, and color-separates incident light into red, green, and blue components. Each photoelectric conversion element corresponds to the spectral transmittance of the color filter 23. Color components, that is, R, G, B analog video signals are output.

  In this way, the R, G, and B analog signals output from the imaging unit 11 (hereinafter may be referred to as “R signal”, “G signal”, and “B signal”, respectively) are amplified by the amplification unit 12. Amplified.

The video signal output from the amplifying means 12 is converted into a digital signal by the ADC 13. The DC level of the video signal converted into the digital signal is reproduced by the DC reproducing means 14. In DC reproduction, the offset level held before the A / D conversion by the ADC 13 is DC-shifted or clamped so that the black level of the normal video signal becomes “0”.
In the present embodiment, the output of the DC reproducing means 14 becomes the output of the color signal generating means 1.

  For example, as shown in FIG. 4, the white balance unit 3 includes amplification units 31r, 31g, and 31b that receive and amplify the R, G, and B signals Ra, Ga, and Ba from the color signal generation unit 1, and amplification units 31r, Accumulating means 32r, 32g, 32b for integrating the outputs Rb, Gb, Bb of 31g, 31b with respect to each of a plurality of pixels, for example, all the pixels in the screen, and outputting integrated values ΣRb, ΣGb, ΣBb, and integrating means Gain control means 33 that receives the integrated values ΣRb, ΣGb, ΣBb from 32r, 32g, 32b and controls the amplification gains of the amplification means 31r, 31g, 31b based on this.

  The luminance / chrominance signal generation unit 4 multiplies the R, G, B signals Rb, Gb, and Bb output from the white balance unit 3 by a coefficient matrix of 3 rows and 3 columns (multiplication with coefficients and multiplication result). Luminance signal (Y signal) and color difference signal (CrCb) are generated.

  The imaging mode selection unit 9 is an input unit for selecting an imaging mode from the outside. For example, a user of the imaging apparatus can perform, for example, a normal imaging mode, a mode in which skin color is imaged in whitening (first corrected imaging mode), An operation is performed to select one of the modes (second correction imaging mode) for capturing an image of a tanned skin color, and a selection result is output. The imaging mode selection means 9 is constituted by, for example, an operation input key or a combination of a menu screen and selection input means.

The luminance signal gradation conversion means 5 performs gradation conversion of the luminance signal Y and has input / output characteristics (gradation conversion characteristics) represented by a polygonal line function. This broken line function has three or more broken points. The luminance signal gradation conversion 5 performs nonlinear conversion based on such input / output characteristics.
The color difference signal gradation conversion means 6 performs gradation conversion of the color difference signal CrCb and has input / output characteristics (gradation conversion characteristics) represented by a polygonal line function. This broken line function has three or more broken points. The color difference signal gradation conversion 6 performs non-linear conversion by such input / output characteristics.
The gain adjusting means 7 adjusts the saturation (color saturation) of the output of the color difference signal gradation converting means 6 with an adjustable gain.

The imaging mode control means 8 sends control signals to the luminance signal gradation conversion means 5 and the color difference signal gradation conversion means 6 according to the selection signal from the imaging mode selection means 9, and controls their input / output characteristics. .
The imaging mode control means 8 also sends a control signal to the gain adjustment means 7 in accordance with the selection signal from the imaging mode selection means 9 to control the gain.

  FIG. 5 shows the spectral reflectances of nine skin colors in the range of 400 nm to 700 nm (see Patent Document 4). Further, FIG. 6 shows spectral reflectance characteristics for six types of skin colors. When the skin color of men (curve SC3 in FIG. 6) is used as a reference, the makeup skin has a high reflectance over the entire wavelength range as shown by the curve SC5 in FIG. 6, resulting in a white skin color. On the other hand, the tanned skin has a low reflectance over the entire wavelength range as shown by a curve SC7 in FIG. 6, resulting in a dark skin color.

  From these, by performing signal processing as follows, control is performed to image the skin color to be whitened or to image the skin color that is tanned.

FIG. 7 shows the input / output characteristics of the luminance signal gradation converting means 5. The horizontal axis is the input signal, and the vertical axis is the output signal. FIG. 7 shows three input / output characteristics (a), (b), and (c), each of which is represented by a line function having three break points. Conversion characteristics are obtained.
The position of the break point can be changed, for example, by designating coordinate values, and the input / output characteristics can be changed by changing the position of the break point. The three input / output characteristics shown in FIG. 7 indicate that such a change is possible, and do not indicate that the number of input / output characteristics after the change is limited to three.
In the illustrated example, the characteristic (a) generally has a higher output signal level relative to the input signal than the characteristic (b), and the characteristic (c) generally has a lower output signal level relative to the input signal than the characteristic (b). .
In general, the image with the characteristic (a) in FIG. 7 is referred to as a “soft image” because the image has a low contrast, and the image with the characteristic (c) in FIG. Is said.

In FIG. 7, y1 represents the level range (input signal level range) y1 of the luminance signal Y input to the luminance signal gradation converting means 4 when the skin color is imaged with the color to be corrected as skin color. .
The input / output characteristics (a), (b), and (c) shown in FIG. 7 are outputs when the amount of change in the output signal level in the input signal level range y1 when the skin color is imaged is outside the input signal level range y1. The amount of change of the signal level is larger than that, and the joint portion between the input signal level range y1 and the outside of the input signal level range y1 is made as unnatural as possible, and the amount of change is made as small as possible.
As described above, in the illustrated example, each broken line has three break points. Although it is possible to achieve an input / output characteristic that is close to a smooth curve even with one breakpoint, the more breakpoints are better if the color to be corrected is appropriately corrected, and there is one breakpoint. In this case, the influence on colors other than the target color tends to be large. If there are two break points, the upper and lower limits of the correction range can be determined by the signal level. Therefore, it is desirable that there are at least two break points, and it is even more desirable that there are three or more break points.

FIG. 8 shows the input / output characteristics of the color difference signal gradation converting means 6. The horizontal axis is the input signal, and the vertical axis is the output signal. FIG. 8 shows three input / output characteristics (d), (e), and (f), each of which is represented by a line function having three break points. Conversion characteristics are obtained.
The position of the break point can be changed, for example, by designating coordinate values, and the input / output characteristics can be changed by changing the position of the break point. The three input / output characteristics shown in FIG. 8 indicate that such a change is possible, and do not indicate that the number of input / output characteristics after the change is limited to three.

  In the illustrated example, the characteristic (e) generally has a higher level of the output signal relative to the input signal than the characteristic (d), and the characteristic (f) generally has a lower level of the output signal relative to the input signal than the characteristic (d). .

In FIG. 8, c <b> 1 indicates a level range (input signal level range) c <b> 1 of the color difference signal CrCb that is input to the color difference signal gradation conversion unit 5 when the skin color is captured using the color to be corrected as the skin color.
The input / output characteristics (d), (e), and (f) shown in FIG. 8 are outputs when the change amount of the output signal level in the input signal level range c1 when skin color is imaged is outside the input signal level range c1. The change amount is larger than the change amount of the signal, and the joint portion between the input signal level range and the input signal level range is not unnatural as much as possible, and the change amount is made as small as possible.

  When performing normal imaging, the luminance signal gradation conversion means 5 and the color difference signal gradation conversion means 6 are generally referred to as gamma correction processing in the imaging apparatus. Y = X ↑ k1 (where “X ↑ k1” is X to the k1th power. The same applies to the following). Here, k1 is an integer. For example, in IEC (International Electrotechnical Commission) 61966-2-1, the gradation characteristic on the display side is set to 2.2, so that 0.45 (reciprocal number of 2.2 on the imaging apparatus side). ) Is used. However, when a value of 0.45 is used, the gain in the dark part of the video signal is increased and the S / N is deteriorated. Is used. Therefore, in the normal imaging mode, the luminance signal gradation converting means 5 selects the characteristic (b) of FIG. 7, and the color difference signal gradation converting means 6 selects the characteristic (e) of FIG.

Next, when the skin color is imaged to “whitening”, an instruction is input from the imaging mode selection means 9 to select a mode for imaging “whitening”. In this imaging mode, the imaging mode control unit 8 outputs a control signal for capturing whitening to the luminance signal tone conversion unit 5, the color difference signal tone conversion unit 6, and the gain adjustment unit 7. The luminance signal gradation converting means 5 selects the characteristic (a) in FIG. 7, and the color difference signal gradation converting means 6 selects the characteristic (f) in FIG. Further, the gain adjusting means 7 changes the gain so that the signal level of the color difference signal CrCb is increased. The impression of the color visible to the human eye changes greatly with saturation (saturation of color) and hue. Normally, when the saturation increases, the color appears darker, and when the hue changes, for example, from red to magenta, from yellow to orange. Such a change occurs. However, the color impression is not determined only by the saturation and the hue, and the appearance of the color varies greatly depending on the balance between the saturation and the luminance at that time (generally referred to as YC balance). That is, even if the saturation and hue are the same, the color impression varies greatly depending on whether the luminance value at that time is large or small. For example, when the brightness is increased while keeping the saturation and hue of the skin color constant, the color looks white, and when the brightness is decreased, the color becomes brownish, and looks like a tanned color. for that reason,
By changing the tone of the luminance signal so that the flesh-colored portion is high, and changing the tone of the color difference signal CrCb so that the chroma of the flesh-colored portion is low, the flesh-color luminance value is increased and the saturation is lowered. It becomes the skin color.
Note that the signal level of the color difference signal CrCb represents the saturation (color saturation) of the color signal.

  As described above, changing the input / output characteristics of the luminance signal gradation converting means 5 and the color difference signal gradation converting means 6 not only changes the level of the luminance signal and color difference signal of only the flesh color part, but also the signal level of the flesh color. The signal value near the level also changes, and the YC balance is shifted over the entire image and becomes whitish. Therefore, the saturation of the entire image is adjusted by increasing the signal level of the color difference signal CrCb by the gain adjusting means 7 so as to correct the whitish image as described above so as not to give an unnatural impression. As a result, although the saturation of the portion of the skin color to which correction is applied is slightly increased, the input / output characteristics of the color signal gradation conversion means 6 are set so that the reduction rate of the output signal at the skin color signal level is maximized, and the luminance is increased. By setting the input / output characteristics of the signal tone conversion means 6 so that the rate of increase of the output signal at the skin color signal level is maximized, the overall image is less unnatural and only the skin color of the face is white. Imaging can be performed as follows.

  In the conventional technique, when whitening is performed, there is a problem that only the saturation is reduced, and the saturation of the entire image is lowered. By making the direction and the direction of change of the tone conversion characteristics of the color difference signal different, processing to increase the saturation (as opposed to the prior art) is performed, and it is desirable to suppress the decrease in the saturation of the entire image. Skin color can be realized.

Next, when imaging the skin color to a tanned color, an instruction is input from the imaging mode selection means 9 to select a mode for imaging the “tanned skin color”. In this imaging mode, the imaging mode control unit 8 outputs a control signal for imaging a tanned skin color to the luminance signal tone conversion unit 5, the color difference signal tone conversion unit 6, and the gain adjustment unit 7. The luminance signal gradation conversion means 5 selects the characteristic (c) in FIG. 7, and the color difference signal gradation conversion means 6 selects the characteristic (d) in FIG. Further, the gain adjusting means 7 changes the gain so that the signal level of the color difference signal CrCb signal becomes small.
By changing the tone of the luminance signal so that the flesh-colored portion becomes lower, and changing the tone of the color difference signal CrCb so that the saturation of the flesh-colored portion becomes higher, the luminance value of the skin color decreases and the saturation increases, and the sunburn It becomes the skin color.

  As described above, changing the input / output characteristics of the luminance signal gradation converting means 5 and the color difference signal gradation converting means 6 not only changes the level of the luminance signal and color difference signal of only the flesh color part, but also the signal level of the flesh color. The signal value at a level close to 1 also changes, and the YC balance is shifted in the entire image, resulting in a darker and darker color. Therefore, the saturation of the entire image is adjusted by reducing the signal level of the color difference signal CrCb by the gain adjusting means 7, and correction is made to the blackish image as described above so as not to give an unnatural impression. Thereby, although the saturation of the skin color portion to which the correction is applied is slightly lowered, the input / output characteristic conversion characteristic of the color difference signal conversion means 6 is set so that the increase rate of the output signal at the skin color signal level is maximized, and The brightness signal tone conversion means 6 has a maximum reduction rate of the output signal at the skin color signal level, so that the whole image is less unnatural and only the skin color of the face is tanned. Images can be taken so as to be in color.

  In the prior art, there is a problem that only the saturation is increased in order to capture the skin color of the sunburn, and the saturation of the entire image is increased, but in this embodiment, the change in the tone conversion characteristics of the luminance signal is changed. By making the direction and the direction of change of the tone conversion characteristics of the color difference signal different, processing to lower the saturation (as opposed to the prior art) is performed, and an increase in the saturation of the entire image is suppressed, which is desirable Skin color can be realized.

Embodiment 2. FIG.
FIG. 9 is a schematic configuration diagram showing an imaging apparatus according to Embodiment 2 of the present invention.
The image pickup apparatus in FIG. 9 is almost the same as the image pickup apparatus shown in FIG. 1, but differs in the following points.
That is, instead of the single color difference signal gradation conversion means 6 of FIG. 1, a first color difference signal gradation conversion means 6a and a second color difference signal gradation conversion means 6b are provided, and the gain adjustment means 7 of FIG. Instead of these, a first gain adjusting means 7a and a second gain adjusting means 7b are provided.
The first chrominance signal gradation converting means 6a performs gradation conversion of the first chrominance signal Cr and has input / output characteristics represented by a polygonal line function. This broken line function has three or more broken points. The color difference signal gradation conversion 6a performs nonlinear conversion by such input / output characteristics.
The second color difference signal gradation conversion means 6b performs gradation conversion of the second color difference signal Cb and has input / output characteristics represented by a polygonal line function. This broken line function has three or more broken points. The color difference signal gradation conversion 6b performs non-linear conversion based on such input / output characteristics.
The first gain adjusting unit 7a adjusts the saturation (color saturation) of the output of the first color difference signal gradation converting unit 6a with an adjustable gain.
The second gain adjusting unit 7b adjusts the saturation (color saturation) of the output of the second color difference signal gradation converting unit 6b with an adjustable gain.

The imaging mode control unit 8 is responsive to a selection signal from the imaging mode selection unit 9 to display a luminance signal tone conversion unit 5, a first color difference signal tone conversion unit 6a, and a second color difference signal tone conversion unit 6b. A control signal is sent to the control unit to control their input / output characteristics (gradation conversion characteristics).
The imaging mode control means 8 also sends control signals to the first and second gain adjustment means 7a and 7b to control their gains.

  As described above, by providing separate gradation conversion means and gain adjustment means for the first color difference signal Cr and the second color difference signal Cb, the gradation conversion characteristics and gains of the two color difference signals Cr and Cb can be obtained. It can be adjusted independently.

FIG. 10 shows an example of input / output characteristics of the first color difference signal gradation converting means 6a, and FIG. 11 shows an example of input / output characteristics of the second color difference signal gradation converting means 6b.
Each of these is represented by a polygonal line function, similar to the input / output characteristics shown in FIG. 8, and can be changed by designating coordinate values.
FIG. 10 shows three characteristics (g), (h), and (i). In the illustrated example, the characteristic (g) generally has a higher level of the output signal relative to the input signal than the characteristic (h). The characteristic (i) generally has a lower level of the output signal relative to the input signal than the characteristic (h).
FIG. 11 shows three characteristics (j), (k), and (l). In the illustrated example, the characteristic (j) generally has a higher level of the output signal relative to the input signal than the characteristic (k). The characteristic (l) generally has a lower level of the output signal relative to the input signal than the characteristic (k).

  At the time of normal imaging, the first color difference signal tone conversion means 6a changes the characteristic of (h) in FIG. 10 to the second color difference signal tone conversion means so that the gamma correction characteristic is obtained as in the first embodiment. 6b selects the characteristic (k) in FIG. In the illustrated example, the characteristics (h) and (k) are substantially the same.

  In FIG. 10, cr1 indicates the level range (input signal level range) of the first color difference signal Cr input to the first color difference signal gradation converting means 6a when the skin color is imaged. In FIG. 10 shows the level range (input signal level range) of the second color difference signal Cb inputted to the second color difference signal gradation converting means 6b when the skin color is imaged, and the input signal level range of FIG. cr1 is higher than the input signal level range cb1 of FIG.

The input / output characteristics (g), (h), and (i) shown in FIG. 10 indicate the amount of change in the output signal level in the input signal level range cr1 of the first color difference signal Cr when the skin color is imaged. The amount of change of the output signal level outside the level range cr1 is larger than that, and the joint portion between the input signal level range cr1 and the outside of the input signal level range cr1 is not unnatural as much as possible, and the amount of change is as small as possible. I am doing so.
Similarly, the input / output characteristics (j), (k), and (l) shown in FIG. 11 indicate the amount of change in the output signal level in the input signal level range cb1 of the second color difference signal Cb when skin color is imaged. It is larger than the change amount of the output signal level outside the input signal level range cb1, and the joint portion between the input signal level range cb1 and the outside of the input signal level range cb1 is not unnatural as much as possible, and the change amount is as much as possible. To make it smaller.

  The operation of the luminance signal gradation converting means 5 of the second embodiment is the same as that of the first embodiment. The gain adjusting means 7a and 7b operate in the same manner as the gain adjusting means 7 of the first embodiment. The operations of the color difference signal tone conversion means 6a and 6b and the gain adjustment means 7a and 7b when imaging “whitening” or “suntanned skin color” will be described below.

  When the skin color is imaged to “whitening”, an instruction is input from the imaging mode selection means 9 to select a mode for imaging “whitening”. In this imaging mode, the imaging mode control means 8 sends control signals for whitening to the luminance signal gradation conversion means 5, the first color difference signal gradation conversion means 6a, and the first color difference signal gradation conversion means 6b. Output. The luminance signal gradation converting means 5 selects the characteristic (a) in FIG. 7 as in the first embodiment, the first color difference signal gradation converting means 6a selects the characteristic (i) in FIG. The second color difference signal gradation converting means 6b selects the characteristic (l) in FIG.

  On the other hand, when imaging the skin color to a tanned color, an instruction is input from the imaging mode selection means 9 to select a mode for imaging the “tanned skin color”. In this imaging mode, the imaging mode control means 8 outputs a control signal for imaging a tanned skin color as a luminance signal gradation conversion means 5, a first color difference signal gradation conversion means 6a, and a first color difference signal gradation conversion means. Output to 6b. The luminance signal gradation converting means 5 selects the characteristic (c) of FIG. 7 as in the first embodiment, the first color difference signal gradation converting means 6a selects the characteristic (g) of FIG. The second color difference signal gradation converting means 6b selects the characteristic (j) in FIG.

  As described above, it is possible to perform correction with higher accuracy by providing independent gradation conversion characteristics for each color value for which the first and second color difference signals Cr and Cb are to be corrected.

The imaging results according to the first and second embodiments are conceptually shown in FIGS. 12 (a) and 12 (b).
FIG. 12A shows an image of a person when normal imaging is performed, and FIG. 12B shows an imaging result when the skin color is imaged in whitening. The skin color of the face portion is shown in FIG. The other portions are substantially the same as in FIG. 12A. FIG. 12C shows an imaging result when imaging is performed with a tanned skin color. The skin color of the face portion is darker than that of FIG. 12A, while the other portions are substantially the same as FIG. 12A. It is.

Embodiment 3 FIG.
FIG. 13 is a schematic configuration diagram showing an imaging apparatus according to Embodiment 3 of the present invention.
The imaging apparatus of FIG. 13 is generally the same as the imaging apparatus shown in FIG. 1, but differs in the following points.
That is, in addition to the components shown in FIG. 1, a weight control unit 41, an integration unit 42, an exposure calculation unit 43, and a timing generator 44 are provided.

The weighting control means 41 divides the screen into a plurality of areas, generates weighting information for each area, and thereby controls the integrating means 42. For example, the weighting coefficient for each region is supplied to the integrating means 42.
The integrating means 42 outputs the R, G, B color signals output from the color signal generating means 1, for example, the R, G, B color signals Ra, Ga, Ba output from the DC reproducing means 14 for one screen or more. Accumulate. For this integration, weighting for each area is performed under the control of the weighting control means 41. The integration means 42 calculates the integration values ΣRa, ΣGa, ΣBa of the R, G, B signals as the integration results.
The exposure control unit 43 controls the exposure of the imaging apparatus so that the integrated values ΣRa, ΣGa, and ΣBa of the R, G, and B signals supplied from the integrating unit 42 are constant.
The timing generator 44 is controlled by the output of the exposure control means 43, and is the image pickup means 11 (FIG. 2) of the color signal generation means 1, particularly the image pickup element 22 (FIG. 3) (FIG. The charge storage time is controlled by changing the timing of the drive pulse applied to the image sensor 22 while the other components in the color signal generator 1 are not shown) Thereby, the signal level output from the imaging means 11 is adjusted.

  The R, G, B signals Ra, Ga, Ba output from the color signal generating means 1 are integrated by one or more screens by the integrating means 42, and the integrated values ΣRa, ΣGa, ΣBa are sent to the exposure control means 43 for exposure control. A control signal corresponding to this is supplied from the means 43 to the timing generator 44, whereby exposure control of the image pickup apparatus is performed so that the integrated values ΣRa, ΣGa, ΣBa are constant. Exposure control is performed by changing the generation timing of the drive pulse by the timing generator 44.

In the above description, the R, G, B signals Ra, Ga, Ba output from the color signal generating unit 1 are integrated. However, the R, G, B signals Ra, Ga, Ba are integrated in the integrating unit 42. For example, Y = k1 × Ra + k2 × Ga + k3 × Ba
(K1, k2, and k3 are predetermined coefficients)
The obtained luminance signal Y may be integrated. Alternatively, only the G signal may be integrated instead of the luminance signal Y.

  As described above, the weighting control unit 41 performs weighting for each area on the screen when the integrating unit 42 integrates one image. FIG. 14 shows an example of the screen division. In FIG. 14, one screen is divided into nine areas of Z11 to Z33 in three rows and three columns. The weighting control means 41 performs screen division shown in FIG. 14, weights each of the areas Z11 to Z33, and the integrating means 42 outputs a weighting coefficient.

When the skin color is imaged to “whitening” or “tanned skin color”, the imaging mode control unit 8 performs luminance signal tone conversion unit 5, color difference signal tone conversion unit 6, gain adjustment unit as described in the first embodiment. 7 outputs a control signal, and each means performs the operation described in the first embodiment.
On the other hand, the imaging mode control unit 8 also outputs a control signal to the weighting control unit 41. In the areas Z11 to Z33 shown in FIG. 14, the weighting control means 41 performs greater weighting on signals in areas where there is a high probability that a human face is located when taking an image. For example, as in the example shown in FIG. 12, the image is often taken with the face positioned in the center in the horizontal direction and the center or the upper side in the vertical direction, that is, the regions Z12 and Z22 in FIG. Therefore, large weighting is performed on the signals of the regions Z12 and Z22. For example, w times (for example, w = 2) are weighted to other regions. In this case, the integrated value obtained by the integrating means 42 is shown for the R signal Ra as follows.
ΣRa = ΣR11 + wΣR12 + ΣR13
+ ΣR21 + wΣR22 + ΣR23
+ ΣR31 + ΣR32 + ΣR33
Here, ΣR11, ΣR12, ΣR13, ΣR21, ΣR22, ΣR23, ΣR31, ΣR32, and ΣR33 are integrations of R signals in the regions Z11, Z12, Z13, Z21, Z22, Z23, Z31, Z32, and Z33, respectively.

  Instead of setting the weight for each region as described above, each pixel may be weighted according to its position.

  In this way, by increasing the weighting of the area where the human face is located, the signal level of the skin color area to be corrected becomes constant, and the skin color correction is easily performed by the gradation conversion means, so that high-accuracy imaging can be performed. It can be carried out.

Embodiment 4 FIG.
FIG. 15 is a schematic configuration diagram showing an imaging apparatus according to Embodiment 4 of the present invention. The image pickup apparatus in FIG. 15 is generally the same as the image pickup apparatus shown in FIG. 13, but differs in the following points. That is, among the components shown in FIG. 13, the timing generator 44 is not provided. Instead, the aperture 45 and the aperture drive unit 46 are provided in the color signal generation unit 1. In FIG. 15, the diaphragm 45 in the color signal generation unit 1 is shown together with the optical system 21 and the image sensor 22, while other components in the color signal generation unit 1 are not shown.

  The operations of the weighting control means 41, the integrating means 42, and the exposure control means 43 are the same as those in the third embodiment. The fourth embodiment is different from the third embodiment in that exposure control is performed not by the timing generator 44 but by the aperture 45. That is, a control signal for performing exposure control of the image pickup apparatus so that the integrated values ΣRa, ΣGa, ΣBa of the R, G, B signals supplied from the integrating means 42 are constant is supplied to the aperture driving means 46. The diaphragm 45 is driven in accordance with the control signal, whereby exposure control of the imaging apparatus is performed so that the integrated values ΣRa, ΣGa, and ΣBa are constant.

  Note that the diaphragm 45, the diaphragm driving means 46, and the timing generator 44 are all provided, and exposure control is performed both by driving the diaphragm 45 by the diaphragm driving means 46 and by changing the generation timing of the drive pulse by the timing generator 44. May be.

  In Embodiments 1 to 4 described above, the skin color is the correction target color, but the present invention can also be applied to cases where the correction target color is other than the skin color.

Embodiment 5 FIG.

  The imaging devices of Embodiments 1 to 4 are applied to a video camera that captures moving images and still images, a camera-integrated VTR, a digital still camera, a PC camera, a mobile phone, and a digital still camera built in a mobile terminal. Can do. A configuration when applied to a digital still camera will be described below with reference to FIG.

  As shown in FIG. 16, this digital camera includes a color signal generation unit 50 instead of the color signal generation unit 1 among the elements constituting the imaging apparatus shown in FIG. 1, and further includes a shutter button 52 and a shutter drive. Means 53, display drive means 54, monitor 55, image compression means 56, and writing means 57 are added.

The shutter drive unit 53 drives the shutter in the color signal generation unit 1 according to the operation of the shutter button 52. Here, the shutter is a mechanical shutter 51 (in FIG. 16, the shutter 51 in the color signal generation unit 50 is shown together with the optical system 21 and the image sensor 22, while other components in the color signal generation unit 50 are shown. The illustration is omitted.).
When the shutter is composed of an electronic shutter, a shutter driving means 53 and a timing generator (for example, as shown in FIG. 15) are integrally configured, and a circuit having both functions is used.
The display driving means 54 receives the outputs of the luminance signal gradation converting means 5 and the gain adjusting means 8 and displays an image on a monitor 55 as a viewfinder.
The monitor 55 is composed of, for example, a liquid crystal display device, and is driven by the display driving unit 54 to display an image captured by the imaging unit in the color signal generation unit 50.
The image compression means 56 receives the outputs of the luminance signal gradation conversion means 5 and the gain adjustment means 8 and performs image compression in accordance with, for example, JPEG.
The writing unit 57 writes the data compressed by the image compression unit 56 to the recording medium 58.

  When the image pickup apparatus is used for moving image shooting and image data is transmitted to a device (not shown), the output of the luminance / color difference signal generation means is encoded to generate and output an NTSC signal.

1 is a block diagram illustrating an imaging apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows the structure of the color signal production | generation means of the imaging device of FIG. It is a figure which shows the structure of the imaging means of FIG. It is a block diagram which shows the structure of the white balance means of FIG. It is a figure which shows the spectral reflectance of nine types of skin colors. It is a figure which shows the numerical value of a spectral reflectance about six types of nine types of skin colors of FIG. It is a figure which shows the input-output characteristic of the luminance signal gradation conversion means of FIG. It is a figure which shows the input / output characteristic of the color difference signal gradation conversion means of FIG. It is a block diagram which shows the imaging device of Embodiment 2 of this invention. It is a figure which shows the input / output characteristic of the 1st color difference signal gradation conversion means of FIG. It is a figure which shows the input-output characteristic of a 2nd color difference signal gradation conversion means. It is a figure which shows the result of the imaging by Embodiment 1 and Embodiment 2. FIG. It is a block diagram which shows the imaging device of Embodiment 3 of this invention. It is a figure which shows the division | segmentation into the several area | region of a screen. It is a block diagram which shows the imaging device of Embodiment 3 of this invention. It is a block diagram which shows the digital still camera provided with the imaging device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Color signal generation means, 3 White balance means, 4 Luminance color difference signal generation means, 5 Luminance signal gradation conversion means, 6 Color difference signal gradation conversion means, 7 Gain adjustment means, 8 Imaging mode control means, 10 Imaging mode selection means 11 imaging means, 12 amplifying means, 13 ADC, 14 DC reproducing means, 21 optical system, 22 imaging device, 23 filter, 31r, 31g, 31b amplifying means, 32r, 32g, 32b integrating means, 33 gain adjusting means, 41 Weight control means, 42 integration means, 43 exposure control means, 44 timing generator, 45 aperture, 46 aperture drive means.

Claims (8)

In an imaging device capable of correcting a specific color,
Color signal generating means for receiving incident light, separating the incident light into at least three color components, and outputting color signals corresponding to the at least three color components;
A luminance color difference signal generating means for receiving the color signal and generating a luminance signal and a color difference signal;
A luminance signal gradation conversion means for receiving the luminance signal output from the luminance color difference signal generation means and performing gradation conversion;
A color difference signal gradation conversion means for receiving the color difference signal output from the luminance color difference signal generation means and performing gradation conversion;
Gain adjusting means for receiving the output of the color difference signal gradation converting means, amplifying it with an adjustable gain, and outputting it;
The luminance signal gradation conversion means changes the output signal when the change amount of the output signal in the level range of the luminance signal input to the luminance signal gradation conversion means is outside the level range when the correction target color is imaged. The input / output characteristics can be changed to be larger than the quantity,
The chrominance signal gradation converting means changes the output signal when the change amount of the output signal in the level range of the chrominance signal input to the chrominance signal gradation converting means is outside the level range when the correction target color is imaged. The input / output characteristics can be changed to be larger than the quantity,
When the color difference signal gradation converting means changes its input / output characteristics, the gain adjusting means changes the output signal of the color difference signal gradation converting means due to the change of the input / output characteristics in the color difference signal gradation converting means. The imaging apparatus is characterized in that the gain is adjusted so that the output signal changes in a direction opposite to the direction.   The imaging apparatus according to claim 1, further comprising selection input means for designating the correction target color. The correction target color is skin color, and in the first correction imaging mode,
The luminance signal gradation conversion means is input so that an output signal in a level range of the luminance signal input to the luminance signal gradation conversion means when a human skin color is imaged is larger than that during normal imaging. Change the output characteristics,
The color difference signal gradation converting means inputs so that an output signal in a level range of the color difference signal inputted to the color difference signal gradation converting means when a human skin color is imaged becomes smaller than that during normal imaging. Change the output characteristics,
The imaging apparatus according to claim 1, wherein the gain adjusting unit increases the gain. In the second correction imaging mode, the correction target color is skin color,
The luminance signal gradation converting means is input so that an output signal in a level range of the luminance signal inputted to the luminance signal gradation converting means when a human skin color is imaged is smaller than that during normal imaging. Change the output characteristics,
The color difference signal gradation converting means is input so that an output signal in a level range of the color difference signal inputted to the color difference signal gradation converting means when a human skin color is imaged is larger than that during normal imaging. Change the output characteristics,
The imaging apparatus according to claim 1, wherein the gain adjusting unit reduces the gain with respect to a color difference signal. In the correction imaging mode to correct a specific color,
The luminance signal gradation conversion means changes the output signal when the change amount of the output signal in the level range of the luminance signal input to the luminance signal gradation conversion means is outside the level range when the correction target color is imaged. Change its input / output characteristics to be larger than the quantity,
When the color difference signal gradation converting means captures a color to be corrected, the amount of change in the output signal in the level range of the color difference signal input to the color difference signal gradation converting means is outside the level range. The image pickup apparatus according to claim 1, wherein the input / output characteristics are changed so as to be larger. Integrating means for integrating at least one of the color signals output from the color signal generating means or a luminance signal obtained by converting the color signals over the entire screen to obtain an integrated value;
Weighting control means for controlling to perform different weighting according to the position of the screen at the time of integration by the integration means;
Exposure control means for supplying an exposure control signal to the color signal generating means according to the output of the integrating means,
The imaging apparatus according to claim 1, wherein the color signal generation unit adjusts a level of an output color signal in accordance with the exposure control signal.   The imaging apparatus according to claim 6, wherein when the person is imaged, the weighting control unit weights an area on the screen where a person's face is likely to be located larger than other areas. . An imaging device according to any one of claims 1 to 7,
A camera comprising means for writing image data output from the imaging device to a recording medium.

Images