Color image processing apparatus with image corrector

An image signal processing apparatus comprising:

• image input means for optically scanning an input image and for generating an electrical image signal which represents the input image, said image input means comprising a proximity linear image sensing unit having linear image sensor sub-units, the improvement comprising:
• (a) light source means, provided to said image input means, for emitting light having discontinuous spectral distribution characteristics in order to optically scan the input image;
• (b) color-separation filter means, provided to each of said linear image sensor sub-units and having discontinuous spectral distribution characteristics in accordance with those of said light source means, for reducing or removing color nonuniformity caused by a variation in sensing characteristics among said image sensor sub-units;
• and
• (c) compensation means for performing compensation processing including shading compensation and sensitivity nonuniformity compensation of the image signal by one-dimensional non-linear conversion and addition/subtraction.

A color copying machine comprising:

• scanner means for optically scanning an input original image and for generating color signals for each pixel of the input image as an image signal representing the input image, said scanner means comprising a proximity linear sensor image sensing unit having an array of linear image sensor sub-units;
• color printer means for producing a copy image corresponding to the input image at limited levels of printing density;
• and
• color conversion means for converting the color signals into ink amount designation signals of the color printer means, the improvement comprising:
• (a) light source means, provided to said scanner means, for emitting light having discontinuous spectral distribution characteristics in order to optically scan the input image;
• (b) color separation filter means, provided to each of said linear image sensor sub-units and having discontinuous spectral distribution characteristics in accordance with those of said light source means, for reducing or removing color nonuniformity of the image signal caused by a variation in sensing characteristics among said image sensor sub-units;
• (c) first processing means, connected to said color conversion means, for at least partially discriminating a type of the input image based on a pattern matching technique, and for producing a discrimination signal which specifies a discriminated type of the input image in a pixel region of a predetermined size of the input image;
• (d) second processing means, connected to said color conversion means and said first processing means, for performing a different kind of image signal correction processing which is selected in accordance with the discriminated type of the input image in response to the discrimination signal, and for producing a corrected image signal;
• and
• (e) third processing means, connected to said second processing means, for performing multi-value dither processing of the corrected image signal, and for producing a drive signal for said printer means, said drive signal defining a printing pixel pattern for each pixel of the input image.