Method and apparatus for tone adjustment correction on rendering gray level image data

A method for producing an image, comprising:

• comparing gray level unrendered pixel values of the image with threshold values and generating first signals representing gray level rendering pixel values for the image;
• providing a tone adjustment to said first signals to generate second signals representing tone corrected gray level rendering pixel values;
• and
• in response to said second signals producing a gray level reproduction of the image.

An apparatus for producing an image, comprising:

• image generating means for generating digital signals representing pixels of an image to be produced;
• a first signal producing means coupled to the image generating means to receive the digital signals representing the image and in response producing a first signal corresponding to a gray level halftoned representation of the image;
• a printer coupled to the first signal-producing means for receiving said first signal and in response to said first signal producing a gray level halftoned reproduction of the image;
• wherein the first signal producing means includes:
• (a) means for generating a gray level rendering pixel value for the pixel of interest from threshold values associated with a halftone screen mask set,
• (b) means for modifying said gray level rendering pixel value by generating a tone corrected gray level pixel value for use in printing the pixel of interest, and
• (c) means for outputting said tone corrected gray level pixel value as said first signal.

A method for producing an image, comprising:

• comparing gray level unrendered pixel values of the image with threshold values and generating first signals representing tone corrected gray level rendering pixel values for the image that are approximately tone corrected for the production process;
• in response to said first signals generating second signals representing tone adjustments to the tone corrected gray level rendering pixel values;
• and
• in response to said second signals producing a gray level reproduction of the image.