US 5,335,097 AGranted

Color tone correcting apparatus

AssigneeDainippon Screen Mfg. Co., Ltd.

InventorShigeo Murakami

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Abstract

Where color components of output signals are RGB signals, a pixel in an original image displayed on a monitor screen is designated to designate RGB signals of a color to be corrected. At the same time, RGB signals of a target color are inputted through a data input device. An effective range of tone correction processing is designated through the data input device based on hue H, saturation S and lightness L with reference to the color to be corrected. Default values are used as an alternative to the designation. The RGB values of pixels in the original image are converted into HSL values to determine whether the pixels are within the effective range expressed by the HSL values. If the pixels are within the effective range, a tone correction is effected by applying parameters derived from the color to be corrected (RGB signals) and target color (RGB signals) to the RGB signals of the pixels. These parameters are amended to be the smaller toward boundaries of the effective range.

Claims38

Dependent claims

A color tone correcting apparatus for effecting a color tone correction of an original image, where color components of output signals are signals (RGB signals) of R (red), G (green) and B (blue), by converting the RGB signals into RGB signals of a target color, said apparatus comprising:

original image data storage means for storing digitalized RGB signals of pixels in said original image;
an image data conversion table for converting said RGB signals into three attribute values (i.e. hue H, saturation S and lightness L:
HSL values) of perceived colors;
processing condition designating means for designating a color to be corrected and to act as a central object for tone correction processing, and for designating a target color resulting from the tone correction;
effective range determining means for determining, from the HSL values, an effective range of the tone correction processing with reference to said color to be corrected;
parameter computing means for computing parameters for use in the tone correction processing based on said color to be corrected and said target color designated by said processing condition designating means;
object pixel determining means for determining pixels subjected to the tone correction processing by comparing the HSL values obtained by applying said RGB signals of pixels in said original image stored in said original image data storage means to said image data conversion table, and the HSL values determined by said effective range determining means and indicative of the effective range of tone correction processing;
and
tone correction processing means for effecting the tone correction processing by applying the parameters computed by said parameter computing means to the RGB signals of pixels determined by said object pixel determining means to be objects of the tone correction processing.

6 more elements

A color tone correcting apparatus for effecting a color tone correction of an original image, where color components of output signals are signals (CMYK signals) of C (cyan), M (magenta), Y (yellow) and K (black), by converting the CMYK signals into CMYK signals of a target color, said apparatus comprising:

original image data storage means for storing digitalized color component signals (RGB signals) of R (red), G (green) and B (blue) of pixels in said original image;
RGB/CMYK converting means for converting said RGB signals into said CMYK signals;
an image data conversion table for converting said RGB signals into three attribute values (i.e. hue H, saturation S and lightness L:
HSL values) of perceived colors;
processing condition designating means for designating RGB signals (signals to be corrected) of a color to be corrected and to act as a central object for tone correction processing from the RGB signals stored in said original image data storage means, and for designating CMYK signals (target signals) of a target color resulting from the tone correction effected for said color to be corrected;
effective range determining means for determining, from the HSL values, an effective range of the tone correction processing with reference to said color to be corrected;
parameter computing means for computing parameters for use in the tone correction processing based on CMYK signals for the tone correction converted by said RGB/CMYK converting means from the signals designated by said processing condition designating means to be corrected, and said target signals designated by said processing condition designating means;
object pixel determining means for determining pixels subjected to the tone correction processing by comparing the HSL values obtained by applying said RGB signals of pixels in said original image stored in said original image data storage means to said image data conversion table, and the HSL values determined by said effective range determining means and indicative of the effective range of tone correction processing;
and
tone correction processing means for effecting the tone correction processing by applying the parameters computed by said parameter computing means to the CMYK signals of pixels determined by said object pixel determining means to be objects of the tone correction processing among the CMYK signals obtained by successively applying the RGB signals of pixels of the original image stored in said original image data storage means to said RGB/CMYK converting means.

7 more elements

Dependencies are inferred from the claim text.