US 7,460,275 B2 · Odd/even error diffusion filter

Abstract

An error diffusion method and system to ameliorate the effects of data quantization. The error diffusion method is especially well-suited to display systems that process groups of pixels in a given row (318) simultaneously. Errors generated when processing pixels in one row (318) of a first group (314) cannot be propagated to other pixels in the same row (318) of the same group (314) since the other pixels are processed by the time the error signal is available. The method and system pass errors from most of the pixels (302) in the group (314) to pixels below and to the right in the next row (320) of the same group (314). Errors from the last pixel (304) in the group (314) are passed to the pixel (308) in the following row (320) beneath the last pixel (304) and to the first pixel (310) in the next group (316) of pixels in the same row (318). To avoid creation of structured visual patterns, a white noise signal is added to the error signals. The noise error signal is created by generating a pseudo random number and adding the pseudo random number to one portion of the error signal while subtracting the pseudo random number from a second portion of the error signal. In effect, the pseudo random number changes the allocation of the error to among adjacent pixels, thus avoiding the structured visual artifacts caused by using deterministic diffusion filter coefficients.

Claims25

Dependent claims

A method of performing error diffusion, the method comprising the steps of:

simultaneously processing image data for at least two pixels in a row of pixels, said at least two pixels comprising a first group of pixels and a last pixel, said last pixel abutting a group of pixels to be processed next in said row of pixels;
reducing the precision of said image data to produce a modified image data word and an error word for each pixel;
propagating none of said error word for each pixel in said first group to another pixel in said first group and a portion of said error word for each pixel in said first group to at least two pixels in a next row of pixels;
and
propagating a first portion of said error word for said last pixel to at least one pixel in said next row of pixels and a second portion of said error word for said last pixel to at least one pixel in said group of pixels to be processed next;
outputting a data signal for causing a display corresponding to said at least two pixels in said next row of pixels at least in part in response to said portion of said error word for a pixel in said first group;
and
outputting a data signal for causing a display corresponding to said at least one pixel in said group of pixels to be processed next at least in part in response to said second portion of said error word.

5 more elements

A display system comprising:

a controller for receiving and processing pixelated image data said controller:
simultaneously processing image data for at least two pixels in a row of pixels, said at least two pixels comprising a first group of pixels and a last pixel, said last pixel abutting a group of pixels to be processed next in said row of pixels;
reducing the precision of said image data to produce a modified image data word and an error word for each pixel;
propagating none of said error word for each pixel in said first group to another pixel in said first group and a portion of said error word for each pixel in said first group to at least two pixels in a next row of pixels;
and
propagating a first portion of said error word for said last pixel to at least one pixel in said next row of pixels and a second portion of said error word for said last pixel to at least one pixel in said group of pixels to be processed next;
a light source for generating a beam of light along a first light path;
and
a light modulator for selectively modulating light along said first light path in response to image data signals from said controller.

6 more elements

Dependencies are inferred from the claim text.

Odd/even error diffusion filter

Life of this patent

Odd/even error diffusion filter

Life of this patent

Abstract

Claims25