Method and apparatus for improving full color images using process black and printer black

A method for converting a 3-color output-color input image to a 4-color output image comprising:

• (1) inputting the 3-color output-color image, the output color image comprising a plurality of pixels, each pixel having a first output color component, a second output color component and a third output color component;
• (2) converting the output-color image to an original color image;
• (3) selecting one of the pixels;
• (4) determining first, second and third original color values of the selected pixel for first, second and third original color components;
• (5) determining a neutral intensity value based on the determined original color values;
• (6) determining an output black-color intensity value component of the determined neutral color intensity value, wherein the output black color intensity value component comprises a printer-black color component and a process-black color component, the printer-black color component value determined based on printer-producible black component values;
• (7) determining first, second and third output color intensity values for the selected pixel based on the determined original color values and the determined output black color intensity value;
• (8) converting the selected pixel having the first, second and third input color components to a selected output pixel having the first, second and third output-color components;
• (9) combining the first, second and third output color components with the determined output black color value to form a 4-color output image pixel;
• (10) repeating steps 3-9 for each remaining original pixel, thereby creating a 4-color output image;
• and
• (11) outputting the 4 -color image.

An apparatus for converting a 3 color original image to a 4 color output image, comprising:

• a first memory for storing at least one pixel of the 3 color original image, the image comprising a plurality of pixels and having 3 color components, each pixel having a first original color component value, a second original value and a third original color component value;
• a neutral component determining means for determining at least one of a neutral component value, a black component value and a printer-producible black component value for each of the plurality of pixels;
• a boosted color component determining means for determining a boosted first original color component value, a boosted second original color component value and a boosted third original color component value for each of the plurality of pixels;
• an output color component determining means for determining a first output color component value, a second output color component value and a third output color component for each of the plurality of pixels;
• and
• a second memory for storing for at least one pixel at least the printer-producible black component value and the first, second and third output color component values of each of the plurality of pixels.

A method for improving color output images, comprising:

• (1) inputting an original full color image comprising original color components, the image comprising a plurality of pixels, each pixel having original color component values;
• (2) selecting one of the plurality of pixels;
• (3) determining original color component values for the original color components of the selected pixel;
• (4) determining a neutral component value of the selected pixel;
• (5) determining a printer black component value of the neutral value component;
• (6) determining boosted original color component values by scaling the original color component values by a function of the printer black component value;
• (7) generating a converted pixel comprising non-black output color components based on the boosted non-black original color component values of the selected pixel;
• (8) repeating steps 2-7 for remaining ones of the plurality of pixels to create a converted image;
• and
• (9) outputting the converted image.

A method for improving color output images, comprising:

• (1) inputting an original full color image comprising original color components, the image comprising a plurality of pixels, each pixel having original color component values;
• (2) selecting one of the plurality of pixels;
• (3) determining original color component values for the original color components of the selected pixel;
• (4) determining a largest one of the original color component values for each pixel;
• (5) determining a neutral component value of the selected pixel based on the determined largest original color component value;
• (6) determining a printer black component value of the neutral value component;
• (7) determining boosted original color component values based on the printer black component value;
• (8) generating a converted pixel comprising non-black output color components based on the boosted non-black original color component values of the selected pixel;
• (9) repeating steps 2-8 for remaining ones of the plurality of pixels to create a converted image;
• and
• (10) outputting the converted image.