Apparatus for non-linear error diffusion thresholding of multilevel video images

Claim 2

Apparatus for performing error diffusion thresholding of multiple level digital video images into bi-level images using non-linear error signals for error diffusion, said apparatus comprising: means for scanning a halftone image and detecting the density levels of individual pixels; means for formulating a grayscale matrix of pixels; means for delaying input pixels by a predetermined number of pixel locations per line; means for delaying input pixels by a predetermined number of scan lines; means for geneating non-linear error values containing either positive or negative sign information; means for adding or subtracting said error values from said predetermined number of delayed pixel values and checking to insure that the calculated value is within a predetermined range; and means for generating an output value.

Claim 3

The apparatus according to claim 1 wherein said non-linear error generating means comprises a programmable read only memory containing pre-defined error functions.

Claim 4

The apparatus according to claim 1 wherein said non-linear error generation means comprises random access memories that contain predefined error values that are generated by a computer.

Claim 5

The apparatus according to claim 1 wherein said output generating means comprises a random access memory that contains a predefined value provided by a computer.

Claim 6

The apparatus according to claim 1 wherein said output generation means comprise means for outputting the most significant bit of the inputted pixel value.

Claim 7

Apparatus for performing error diffusion thresholding of multiple level digital images into a bi-level image using look-up tables to perform calculation of error signals to be diffused, said apparatus comprising: means for scanning a halftone image and detecting the density levels of the individual pixels; first array forming means for delaying the incoming pixels by a predetermined number of pixels in a scan line; second array forming means for delaying said pixel values by a predetermined number of scan lines; a programmable read only memory containing predefined error functions for generating a non-linear error value; means for adding or subtracting said error values to said delayed pixels in said array form means and checking to insure that the calculated value is within a predetermined range; and means for using a programmable read only memory containing predefined error functions for generating a non-linear error value to be combined with said current pixel and outputting after said combination, the most significant bit for the pixel value.

Claim 8

Apparatus for performing error diffusion thresholding of multiple level digital images into a bi-level image using look-up tables to perform calculation of error signals to be diffused, said apparatus comprising: means for scanning a halftone image and detecting the density levels of the individual pixels; first array forming means for delaying the incoming pixels by a predetermined number of pixels in a scan line; second array forming means for delaying said pixel values by a predetermined number of scan lines; a programmable read only memory containing predefined error functions for generating a non-linear error value; means for adding or subtracting said error values to said delayed pixels in said array form means and checking to insure that the calculated value is within a predetermined range; and means for using a programmable read only memory containing predefined error functions for generating a non-linear error value to be combined with said current pixel and outputting after said combination, the most significant bit for the pixel value.