Color correction apparatus, color correction controller, and color correction system

A color correction system for use with an imaging apparatus, said imaging apparatus including imaging means for sensing the image of a subject and generating a signal including information pertaining to the colors of the subject, said color correction system comprising:

• color representation data generating means for generating color representation data of hue (H), lightness (Y) and saturation (S) representing colors of the image represented by the signal generated by said imaging means in the image sensing operation;
• and
• correction means which divides a color space in which the H, Y and S data is represented in coordinates, into a plurality of regions, and corrects the H, Y and S data generated by said color representation data generating means with respect to H, Y and S data representing a single reference color defined for each respective region, in accordance with a procedure determined for each region of said color space thereby adjusting a color represented by the signal generated by said imaging means with respect to the reference color of the region within which the represented color falls;
• procedure determining means for determining the procedure of dividing the color space into the plurality of regions corresponding to a plurality of said reference colors, and determining a correction procedure performed by said correction means for each said region, in accordance with the signal which is generated by said imaging means when sensing said plurality of reference colors and also in accordance with the color representation data for said plurality of reference colors, so that said color correction controller controls said correction means in accordance with the correction procedure determined;
• wherein:
• said procedure determining means is connected to a reference camera with respect to which color adjustment is performed and is also connected to one or more other cameras to be adjusted in terms of color characteristics with respect to said reference camera,
• the signal generated by the imaging means of said reference camera when sensing said plurality of reference colors is employed to derive said H, Y and S data for the reference colors;
• and
• for each said camera to be adjusted, the correction procedure performed by the correction means of each said camera to be adjusted is determined on the basis of said H, Y and S data for the reference colors and also the signal generated by the imaging means of each said camera to be adjusted when sensing said plurality of reference colors.

A color correction controller for controlling correction means provided in an imaging apparatus, said imaging apparatus comprising:

• imaging means for sensing the image of a subject and generating a signal including information pertaining to the colors of the subject;
• color representation data generating means for generating color representation data of hue (H), lightness (Y) and saturation (S) representing colors of the image represented by the signal generated by said imaging means in the image sensing operation;
• and
• said correction means divides a color space in which the H, Y and S data is represented in coordinates, into a plurality of regions, and corrects the H, Y and S data generated by said color representation data generating means with respect to H, Y and S data representing a single reference color defined for each respective region, in accordance with a procedure determined for each region of said color space thereby adjusting a color represented by the signal generated by said imaging means with respect to the reference color of the region within which the represented color falls;
• said color correction controller comprising procedure determining means for determining the procedure of dividing the color space into the plurality of regions corresponding to a plurality of said reference colors, and determining a correction procedure performed by said correction means for each said region, in accordance with the signal which is generated by said imaging means when sensing said plurality of reference colors and also in accordance with the color representation data for said plurality of reference colors, so that said color correction controller controls said correction means in accordance with the correction procedure determined;
• wherein corrected hue is determined in accordance with the following expressions:
• θa′=θY−(θY−θa)×(θY−Hr1)/(θY−H1);
• θb′=θX+(θb−θX)×(Hr1−θX)/(H1−θX)
• where,
• θY is a hue value of a first boundary of the color space region that the color representation data falls within;
• θX is a hue value of an opposite boundary of said color space region;
• θa is a pre-shift hue value for a point, associated with the generated signal, on a first side of said color space region between a reference hue value and said first boundary;
• θa′ is a shifted hue value for the point corresponding to hue value θa;
• θb is a pre-shift hue value for a point, associated with the generated signal, on a second side of a color space region between said reference hue value and said opposite boundary;
• θb′ is a shifted hue value for the point corresponding to hue value θb;
• Hr1 is said reference hue value;
• and
• H1 is a hue value of said imaging apparatus for the same color corresponding to said reference hue value.

A color correction apparatus for use in an imaging apparatus, said imaging apparatus including imaging means for sensing the image of a subject and generating a signal including information pertaining to the colors of the subject, said color correction apparatus comprising:

• color representation data generating means for generating color representation data of hue (H), lightness (Y) and saturation (S) representing colors of the image represented by the signal generated by said imaging means in the image sensing operation;
• and
• correction means which divides a color space in which the H, Y and S data is represented in coordinates, into a plurality of regions, and corrects the H, Y and S data generated by said color representation data generating means with respect to H, Y and S data representing a single reference color defined for each respective region, in accordance with a procedure determined for each region of said color space thereby adjusting a color represented by the signal generated by said imaging means with respect to the reference color of the region within which the represented color falls;
• wherein corrected saturation is determined in accordance with the following:
• Sa′={SGY−(SGY−SGA′)×(θY−θa′)/(θY−Hr1)}×Sa
• Sb′={SGX−(SGX−SGA′)×(θb′−θX)/(Hr1−θX)}×Sb,
• where,
• θX is a hue value of a first boundary line X1 of the color space region within which the color representation data falls;
• θY is a hue value of an opposite boundary line X2 of said color space region;
• SGX is saturation gain on the boundary line X1;
• SGY is saturation gain on the boundary line X2;
• Sa is a pre-correction saturation value for a first point, “a”, associated with the generated signal, on a first side of said color space region between a value A′ of the reference color and the first boundary line X1;
• Sa′ is a corrected saturation value associated with a point, a′, which is shifted from the first point due to corrected saturation and hue shift;
• Sb is a pre-correction saturation value for a second point, b, associated with the generated signal, on a second side of said color space region between the reference color value and the second boundary line X2;
• Sb′ is a corrected saturation value associated with a point, b′, which is shifted from the second point due to corrected saturation and hue shift;
• θa′ is a shifted hue value associated with the point a′;
• θb′ is a shifted hue value associated with the point b′;
• SGA′ is a saturation gain associated with the reference color value A′;
• and
• Hr1 is a reference hue value associated with the reference color value A′.