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Brooke Vibber 2023-03-21 18:34:14 -07:00
parent 2cc9198e2c
commit b4e3394809
1 changed files with 27 additions and 20 deletions
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47
dither-image.js
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@ -407,11 +407,10 @@ let atariRGB = [
* @param {RGB[]} input source scanline data, in linear RGB
* @param {number[]} palette - current working palette, as Atari 8-bit color values (low nybble luminance, high nybble hue)
* @param {number} n - target color count
* @param {RGB[]} inputError
* @param {number} y
* @returns {{output: number[], palette: number[], error: RGB[]}}
*/
function decimate(input, palette, n, inputError, y) {
function decimate(input, palette, n) {
// to brute-force, the possible palettes are:
// 255 * 254 * 253 = 16,386,810
//
@ -433,9 +432,6 @@ function decimate(input, palette, n, inputError, y) {
if (error) {
rgb.inc(error.cur[x]);
}
if (inputError) {
rgb.inc(inputError[x]);
}
rgb.cap();
return rgb;
};
@ -540,9 +536,9 @@ function decimate(input, palette, n, inputError, y) {
// Median cut!
// https://en.wikipedia.org/wiki/Median_cut
//let buckets = [input.slice()];
let initial = dither(palette);
let buckets = [initial.output.map((i) => atariRGB[palette[i]])];
let buckets = [input.slice()];
//let initial = dither(palette);
//let buckets = [initial.output.map((i) => atariRGB[palette[i]])];
let medianCut = (bucket, range) => {
if (bucket.length < 2) {
console.log(bucket);
@ -582,19 +578,25 @@ function decimate(input, palette, n, inputError, y) {
}
decimated = buckets.map((bucket) => {
// Average the RGB colors in this chunk
//let rgb = bucket
// .reduce((acc, rgb) => acc.inc(rgb), new RGB(0, 0, 0))
// .divide(bucket.length);
// scale to the max luma
let rgb = bucket
.reduce((acc, rgb) => acc.inc(rgb), new RGB(0, 0, 0))
.divide(bucket.length);
let avg_luma = rgb.luma();
let lumas = bucket.map((rgb) => rgb.luma());
let brightest = Math.max(...lumas);
if (avg_luma > 0) {
rgb = rgb.multiply(brightest / avg_luma);
}
// pick the luma-brightest color in the bucket
// kinda nice but really aggressive with the colors
/*
let lumas = bucket.map((rgb) => rgb.luma());
let luma = Math.max(...lumas);
let rgb = bucket[lumas.indexOf(luma)];
let from = rgb.luma();
if (from > 0) {
rgb = rgb.multiply(luma / rgb.luma());
}
*/
// Take the channel-brightest color in the bucket
// bad
@ -615,6 +617,7 @@ function decimate(input, palette, n, inputError, y) {
Math.max(...bucket.map((rgb) => rgb.b))
);
*/
// combine the median of each channel
// sux
/*
@ -734,9 +737,13 @@ async function convert(source) {
let lines = [];
for (let y = 0; y < height; y++) {
let error = lines[y - 1]?.error;
let inputLine = input.slice(y * width, (y + 1) * width);
let line = decimate(inputLine, allColors, 4, error, y);
let inputLine = input
.slice(y * width, (y + 1) * width);
if (y > 0) {
let error = lines[y - 1].error;
inputLine = inputLine.map((rgb, x) => RGB.add(rgb, error[x]));
}
let line = decimate(inputLine, allColors, 4, y);
lines.push(line);
}
return {