encrypting documents and other files
Kevin Church/BBC News
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A notable resource on the topic of ordered dithering using arbitrary palettes is Joel Yliluoma’s Arbitrary-Palette Positional Dithering Algorithm. One key difference of Yliluoma’s approach is in the use of error metrics beyond the minimisation of . Yliluoma notes that the perceptual or psychovisual quality of the dither must be taken into account in addition to its mathematical accuracy. This is determined by use of some cost function which considers the relationship between a set of candidate colours. The number of candidates, the particular cost function, and the thoroughness of the selection process itself give rise to a number of possible implementations, each offering varying degrees of quality and time complexity.
Александра Качан (Редактор)
What surprised me was that this entire walk is fully hardware-driven -- no microcode involvement at all. The state machine reads the page directory entry, reads the page table entry, checks permissions, and writes back the Accessed and Dirty bits, all autonomously. Since it's hardware-driven, it runs in parallel with the microcode and needs its own memory bus arbitration -- the paging unit must share the bus with both data accesses from the microcode and prefetch requests from the instruction queue.