| 摘要 |
<p>A processing chain for a digital image signal (12) applies a dither pattern (14), having a first spectrum, to the image signal at a point in the processing chain. A further noise pattern (10) is applied to the image signal during the processing chain. The noise pattern (10) has a second spectrum which is configured such that the combination of the first spectrum and second spectrum results in a more continuous spectrum. Another aspect describes a noise pattern (10) which can be used as an offset dither pattern for digital images, especially before colour bit depth reduction. The noise pattern comprises an array of values which are linearly distributed across a range, with each value in the range occurring an equal number of times. Similar values at extreme ends of the range of values are dispersed within the array. The pattern has a Poisson-disk two-dimensional spectral energy distribution. Values are positioned in the array based on distance to similar values in neighbouring repetitions of the array. The array has "magic square" properties.</p> |
