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Use more accurate bit for alpha lookup. #2473

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merged 2 commits into from Jun 13, 2023

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Description

Fixes #2469

Our pixel map accuracy wasn't good enough for alpha comparison, so we were leaving artifacts.

This increases memory from 2.26MB to 4.45MB but not only do we fix our issue, as a result of the increased accuracy, we're also getting less collisions in our RGB components.

/// </para>
/// </remarks>
private unsafe struct ColorDistanceCache : IDisposable
{
private const int IndexBits = 5;
private const int IndexAlphaBits = 5;
private const int IndexAlphaBits = 6;
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This could be zero when TPixel doesn't have an alpha. It might be worth to eventually implement some trick to have two versions of EuclideanPixelMap, so we save memory when working with RGB pngs and gifs.

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Good point. We could easily preserve much more accurate matches in less space.

@JimBobSquarePants JimBobSquarePants merged commit bf43044 into main Jun 13, 2023
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@JimBobSquarePants JimBobSquarePants deleted the js/2469-color-LUT-memory branch June 13, 2023 01:36
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Unexpected artefacts when quantizing images
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