Electronic camera having color adjustment function and program therefor

Claim 2

An electronic camera comprising: an imaging section capturing an image of an object; an imaging control section generating a test image and a main image by controlling said imaging section, the test image being captured without a flash, the main image being captured with a flash; a histogram calculating section calculating a histogram distribution for each of the test image and the main image; a histogram correlation judging section judging correlation between two histogram distributions calculated by said histogram calculating section; a white balance calculating section determining a white balance adjustment value, placing importance on a color temperature of a flash, when judging that a flash has not illuminated an object evenly according to a histogram correlation judging section's judgment that the correlation is low, and determining a white balance adjustment value, placing importance on a color temperature of the main image, when judging that a flash has illuminated an object evenly or a flash has not reached an object evenly according to a histogram correlation judging section's judgment that the correlation is high; and a white balance adjusting section adjusts a white balance of the main image in accordance with the white balance adjustment value determined by said white balance calculating section.

Claim 3

The electronic camera according to claim 1 , wherein said white balance calculating section calculates a weighted combination value of a first white balance adjustment value and a second white balance adjustment value as the white balance adjustment value, and increases a weight of the first white balance adjustment value when the correlation is low and increases a weight of the second white balance adjustment value when the correlation is high, the first white balance adjustment value being determined with reference to the color temperature of the flash, the second white balance adjustment value being determined with reference to the color temperature of the main image.

Claim 4

The electronic camera according to claim 1 , wherein said white balance calculating section determines a frequency of white saturation and/or black saturation in the main image, and refrains from judging evenness of the flash illumination if the frequency is higher than a predetermined threshold value.

Claim 5

The electronic camera according to claim 1 , wherein said imaging section further comprises a photometric image sensor performing an imaging operation for divisional photometry and a recording image sensor performing an imaging operation for recording, wherein said imaging control section captures the test image without a flash by controlling said photometric image sensor and captures the main image with a flash by controlling said recording image sensor.

Claim 6

The electronic camera according to claim 4 , wherein said histogram calculating section reduces a difference between the two histogram distributions due to a device difference between said photometric image sensor and said recording image sensor.

Claim 7

The electronic camera according to claim 1 , wherein said histogram correlation judging section detects correlation between the two histogram distributions generated by the histogram calculating section after removing frequencies lower than a predetermined frequency from the two histogram distributions.

Claim 8

An electronic camera comprising: an imaging section capturing an image of an object; an imaging control section generating a test image and a main image by controlling said imaging section, the test image being captured without a flash, the main image being captured with a flash; a histogram calculating section generating a histogram distribution for each of the test image and the main image; a histogram correlation judging section judging correlation between two histogram distributions generated by said histogram calculating section; a special light source determining section detecting a green fog due to illumination by a fluorescent lamp, upon determining that chromaticity of a low-chroma region in the main image is separated from a black body locus; and a color balance adjusting section correcting a green fog by increasing red and blue components of the main image relatively to a green component thereof when judging that the fluorescent lamp illumination is even according to a histogram correlation judging section's judgment that the histogram correlation is high and to the special light source determining section's detection of the green fog in the low-chroma region, and decreasing the green fog correction when judging that the fluorescent lamp illumination is not even according to a histogram correlation judging section's judgment that the histogram correlation is low and to the special light source determining section's detection of the green fog in the low-chroma region.

Claim 9

An electronic camera comprising: an imaging section capturing an image of an object; an imaging control section generating a test image and a main image by controlling said imaging section, the test image being captured without a flash, the main image being captured with a flash; a histogram calculating section generating a histogram distribution for each of the test image and the main image; a histogram correlation judging section judging correlation between two histogram distributions generated by said histogram calculating section; a special light source determining section detecting a green fog due to illumination by a fluorescent lamp, upon determining that chromaticity of a low-chroma region in the main image is separated from a black body locus; and a color balance adjusting section correcting a green fog by increasing red and blue components of the main image relatively to a green component thereof when judging that the fluorescent lamp illumination is even according to a histogram correlation judging section's judgment that the histogram correlation is high and to the special light source determining section's detection of the green fog in the low-chroma region, and decreasing the green fog correction when judging that the fluorescent lamp illumination is not even according to a histogram correlation judging section's judgment that the histogram correlation is low and to the special light source determining section's detection of the green fog in the low-chroma region.

Claim 10

The electronic camera according to claim 7 , wherein said color balance adjusting section calculates a weighted combination value of a white balance adjustment value and a color balance adjustment value if the histogram correlation is judged low and a green fog is detected, and adjusts a color balance of the main image by using the weighted combination value, the white balance adjustment value being determined with reference to a correlation color temperature of the main image which is obtained by mapping to the black body locus, the color balance adjustment value being for correction of the green fog.

Claim 11

The electronic camera according to claim 8 , wherein for the calculation of the weighted combination value said color balance adjusting section decreases the weight of the color balance adjustment as the histogram correlation lowers.

Claim 12

The electronic camera according to claim 7 , wherein said color balance adjusting section prepares predetermined, plural sets of data on correspondence between a color of a low-chroma region and a color balance adjustment value in accordance with kinds of color rendering performance of fluorescent lamps, calculates a color balance adjustment value by using a set of data for higher color rendering performance as the histogram correlation lowers, and adjusts a color balance of the main image according to the calculated color balance adjustment value.

Claim 13

An electronic camera comprising: an imaging section generating an image by shooting an object; a special light source determining section detecting a color fog caused by a special light source by determining that chromaticity of a low-chroma region in the image is separate from a black body locus; an even illumination judging section judging evenness of illumination to the image; and a color balance adjusting section correcting a color fog in such a manner as to reduce a separation of chromaticity of the image from the black body locus if the illumination to the image is judged even and the color fog is detected in said low-chroma region, and decreasing the color fog correction if the illumination to the image is judged uneven and the color fog is detected in said low-chroma region.

Claim 14

An electronic camera comprising: an imaging section generating an image by shooting an object; a special light source determining section detecting a color fog caused by a special light source by determining that chromaticity of a low-chroma region in the image is separate from a black body locus; an even illumination judging section judging evenness of illumination to the image; and a color balance adjusting section correcting a color fog in such a manner as to reduce a separation of chromaticity of the image from the black body locus if the illumination to the image is judged even and the color fog is detected in said low-chroma region, and decreasing the color fog correction if the illumination to the image is judged uneven and the color fog is detected in said low-chroma region.

Claim 15

An electronic camera comprising: an image acquiring section acquiring a non-flash image and a flash image by controlling a flash device, the non-flash image being captured without a flash, the flash image being captured with a flash; a luminance ratio detecting section determining a ratio of luminance Rnf of different regions A and B of a frame of the non-flash image, determining a ratio of luminance Rf of the different regions A and B of a frame of the flash image, and calculating a flash-induced variation C between the luminance ratios Rnf and Rf; and a color balance adjusting section setting a color balance adjustment in such a manner that the larger the variation C is, the greater importance placed on a color temperature of the flash is, and performing a set color balance adjustment on a main image that is captured with a flash.

Claim 16

An electronic camera comprising: an image acquiring section acquiring a non-flash image and a flash image by controlling a flash device, the non-flash image being captured without a flash, the flash image being captured with a flash; a luminance ratio detecting section determining a ratio of luminance Rnf of different regions A and B of a frame of the non-flash image, determining a ratio of luminance Rf of the different regions A and B of a frame of the flash image, and calculating a flash-induced variation C between the luminance ratios Rnf and Rf; and a color balance adjusting section setting a color balance adjustment in such a manner that the larger the variation C is, the greater importance placed on a color temperature of the flash is, and performing a set color balance adjustment on a main image that is captured with a flash.

Claim 17

The electronic camera according to claim 12 , wherein said luminance ratio detecting section determines a ratio of luminance Rnf between a center region of a frame of the non-flash image and a whole frame or a peripheral region of the frame thereof, and determines a ratio of luminance Rf between a center region of a frame of the flash image and a whole frame or a peripheral region of the frame thereof.

Claim 18

The electronic camera according to claim 12 , wherein said color balance adjusting section sets a color balance adjustment in such a manner that the smaller the variation C is, the greater importance placed on a color temperature of the main image or the flash image is, and performs a set color balance adjustment on the main image.

Claim 19

The electronic camera according to claim 12 , wherein said color balance adjusting section decreases green fog correction amount in the color balance adjustment as the variation C increases, the green fog correction amount being for increasing red and blue components relatively to a green component.

Claim 20

The electronic camera according to claim 12 , wherein said image acquiring section comprises: an auxiliary image sensor capturing the non-flash image in a state that the flash device is not flashing; and a main image sensor capturing the flash image in a state that the flash device is flashing, the flash image also serving as the main image.

Claim 21

The electronic camera according to claim 12 , wherein said image acquiring section comprises an auxiliary image sensor capturing the non-flash image before or after the flash device emits a preliminary flash and capturing the flash image while the flash device is emitting a preliminary flash, and a main image sensor capturing the main image in a state that the flash device is emitting a main flash.

Claim 22

A computer-readable medium storing a program that, when executed, causes a computer to function as said histogram calculating section, said histogram correlation judging section, said white balance calculating section, and said white balance adjusting section that are recited in claim 1 .

Claim 23

A computer-readable medium storing a program that, when executed, causes a computer to function as said histogram calculating section, said histogram correlation judging section, said special light source determining section, and said color balance adjusting section that are recited in claim 7 .

Claim 24

A computer-readable medium storing a program that, when executed, causes a computer to function as said special light source determining section, said even illumination judging section, and said color balance adjusting section that are recited in claim 11 .

Claim 25

A computer-readable medium storing a program that, when executed, causes a computer to function as said luminance ratio detecting section and said color balance adjusting section that are recited in claim 12 .