Patent ID: 7327373

Claim:
A dither algorithm, for four-time resolution refining for an image comprising a plurality of frames scanned with a plurality of pixels, each pixel comprising a plurality of bits, an observed unit being a 4×2 block of the pixels, the observed unit having a first sub unit and a second sub unit, each the sub unit comprising a 2×2 block of the pixels, the 2×2 block having an upper-left pixel, an upper-right pixel, a lower-left pixel, and a lower-right pixel, the 2×2 block having an upper row consisting of the upper-left pixel and the upper-right pixel, and having a lower row consisting of the lower-left pixel and the lower-right pixel, the dither algorithm comprising: for each of the pixels of the first sub unit of the observed unit, when the 2-bit least significant bits (LSBs) being 00, no operation is rendered, when the 2-bit LSBs being 01, a first operation is rendered in repeated sequential fashion in a four-frame period to the upper-left pixel, the lower-right pixel, the lower-left pixel, and the upper-right pixel, when the 2-bit LSBs being 10, a second operation is rendered in repeated sequential fashion in a two-frame period to the pixels of the lower row and the pixels of the upper row, when the 2-bit LSBs being 11, a third operation is rendered as the first operation is; and for each of the pixels of the second sub unit of the observed unit, when the 2-bit LSBs being 00, no operation is rendered, when the 2-bit LSBs being 01, a fourth operation is rendered in repeated sequential fashion in the four-frame period to the lower-left pixel, the upper-right pixel, the upper-left pixel, and the lower-right pixel, when the 2-bit LSBs being 10, a fifth operation is rendered in repeated sequential fashion in the two-frame period as the second operation is, when the 2-bit LSBs being 11, a sixth operation is rendered in a repeated sequential fashion in the four-frame period as the fourth operation is.