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No commits in common. "71c19887c7e35edae203e7003e4131ed6ea91081" and "0dcfa88c2991c25cb6d3eec315f071a6739a95bc" have entirely different histories.
71c19887c7
...
0dcfa88c29
5 changed files with 36 additions and 143 deletions
3
Makefile
3
Makefile
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@ -20,7 +20,4 @@ all : sample0.xex \
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clean :
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rm -f *.o
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rm -f *.s.png
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rm -f sample[0-9].s
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rm -f fruit.s mapclock.s sailboat.s sunset.s train404.s
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rm -f potato.s selfie.s kitty.s meme.s
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rm -f *.xex
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135
dither-image.js
135
dither-image.js
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@ -28,17 +28,6 @@ function fromLinear(val) {
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return unit * 255;
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}
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function fromSRGB(val) {
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val /= 255;
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if (val <= 0.04045) {
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val /= 12.92;
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} else {
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val = ((val + 0.055) / 1.055) ** 2.4;
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}
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val *= 255;
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return val;
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}
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function toSRGB(val) {
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val /= 255;
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if (val <= 0.0031308) {
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@ -68,39 +57,6 @@ class RGB {
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return new RGB(r,g,b);
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}
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static fromGTIA(val) {
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// This seems off from what Atari800 does
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// https://forums.atariage.com/topic/107853-need-the-256-colors/page/2/#comment-1312467
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let cr = (val >> 4) & 15;
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let lm = val & 15;
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let crlv = cr ? 50 : 0;
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/*
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let phase = ((cr - 1) * 25 - 58) * (2 * Math.PI / 360);
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let y = 255 * (lm + 1) / 16;
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let i = crlv * Math.cos(phase);
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let q = crlv * Math.sin(phase);
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let r = y + 0.956 * i + 0.621 * q;
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let g = y - 0.272 * i - 0.647 * q;
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let b = y - 1.107 * i + 1.704 * q;
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*/
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// PAL
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let phase = ((cr - 1) * 25.7 - 15) * (2 * Math.PI / 360);
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let y = 255 * (lm + 1) / 16;
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let i = crlv * Math.cos(phase);
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let q = crlv * Math.sin(phase);
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let r = y + 0.956 * i + 0.621 * q;
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let g = y - 0.272 * i - 0.647 * q;
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let b = y - 1.107 * i + 1.704 * q;
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return new RGB(r, g, b).clamp().fromSRGB();
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}
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map(callback) {
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return new RGB(
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callback(this.r),
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@ -109,18 +65,14 @@ class RGB {
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);
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}
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fromNTSC() {
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toLinear() {
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return this.map(toLinear);
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}
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toNTSC() {
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fromLinear() {
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return this.map(fromLinear);
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}
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fromSRGB() {
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return this.map(fromSRGB);
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}
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toSRGB() {
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return this.map(toSRGB);
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}
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@ -182,24 +134,13 @@ class RGB {
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this.b * this.b;
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}
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sum() {
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return this.r + this.g + this.b;
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}
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lumaScale() {
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return new RGB(
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this.r * 0.299,
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this.g * 0.586,
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this.b * 0.114
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);
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}
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luma() {
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return this.lumaScale().sum();
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return this.r * 0.299 + this.g * 0.587 + this.b * 0.114;
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}
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}
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/*
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const maxDist = (new RGB(255, 255, 255)).magnitude();
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// snarfed from https://lospec.com/palette-list/atari-8-bit-family-gtia
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// which was calculated with Retrospecs App's Atari 800 emulator
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let atariRGB = [
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@ -459,16 +400,8 @@ let atariRGB = [
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0xf6e46f,
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0xfffa84,
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0xffff99,
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].map((hex) => RGB.fromHex(hex).fromNTSC());
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].map((hex) => RGB.fromHex(hex).toLinear());
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//].map((hex) => RGB.fromHex(hex));
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*/
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let atariRGB = [];
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for (let i = 0; i < 256; i++) {
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atariRGB[i] = RGB.fromGTIA(i);
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}
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/**
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* Dither RGB input data with a target palette size.
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@ -481,6 +414,19 @@ for (let i = 0; i < 256; i++) {
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* @returns {{output: number[], palette: number[], error: RGB[]}}
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*/
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function decimate(input, palette, n) {
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// to brute-force, the possible palettes are:
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// 255 * 254 * 253 = 16,386,810
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//
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// we could brute force it but that's a lot :D
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// but can do some bisection :D
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//
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// need a fitness metric.
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// each pixel in the dithered line gives a distance
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// sum/average them? median? maximum?
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// summing evens out the ups/downs from dithering
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// but doesn't distinguish between two close and two distant options
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// consider median, 90th-percentile, and max of abs(distance)
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// consider doing the distance for each channel?
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let width = input.length;
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@ -494,6 +440,7 @@ function decimate(input, palette, n) {
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// Apply dithering with given palette and collect color usage stats
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let dither = (palette) => {
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let fitness = zeroes(width);
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let error = {
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cur: [],
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next: [],
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@ -520,7 +467,7 @@ function decimate(input, palette, n) {
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for (let i = 0; i < palette.length; i++) {
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let diff = rgb.difference(atariRGB[palette[i]]);
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let dist = diff.magnitude();
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let dist = diff.magnitude2();
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if (dist < shortest) {
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nextError = diff;
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shortest = dist;
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@ -537,10 +484,21 @@ function decimate(input, palette, n) {
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error.next[x - 1]?.inc(share(3));
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error.next[x ]?.inc(share(5));
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error.next[x + 1]?.inc(share(1));
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let mag = nextError.magnitude();
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fitness[x] = maxDist / mag;
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// 442 is the 3d distance across the rgb cube
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//fitness[x] = 442 - (nextError.magnitude());
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//fitness[x] = 442 / (442 - nextError.magnitude());
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fitness[x] = 255 / (256 - Math.max(0, nextError.r, nextError.g, nextError.b));
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let mag2 = nextError.magnitude2();
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distance2 += mag2;
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}
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return {
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output,
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palette,
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fitness,
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distance2,
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popularity,
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error: error.next
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@ -580,11 +538,7 @@ function decimate(input, palette, n) {
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// Median cut!
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// https://en.wikipedia.org/wiki/Median_cut
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//let buckets = [input.slice()];
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// preface the reserved bits
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let buckets = reserved.slice().map((c) => [atariRGB[c]]).concat([input.slice()]);
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let buckets = [input.slice()];
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let medianCut = (bucket, range) => {
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if (bucket.length < 2) {
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console.log(bucket);
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@ -617,23 +571,8 @@ function decimate(input, palette, n) {
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);
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});
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let topRanges = ranges.map((rgb) => Math.max(rgb.r, rgb.g, rgb.b));
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//let greatest = Math.max(...topRanges);
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//let index = topRanges.indexOf(greatest);
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let greatest = 0;
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let index = -1;
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for (let i = 0; i < topRanges.length; i++) {
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if (topRanges[i] >= greatest) {
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greatest = topRanges[i];
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index = i;
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}
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}
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if (index == -1) {
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// We just ran out of colors! Pad the buckets.
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while (buckets.length < n) {
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buckets.push([new RGB(0, 0, 0)]);
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}
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break;
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}
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let greatest = Math.max(...topRanges);
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let index = topRanges.indexOf(greatest);
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let [lo, hi] = medianCut(buckets[index], ranges[index]);
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buckets.splice(index, 1, lo, hi);
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}
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@ -665,11 +604,9 @@ function decimate(input, palette, n) {
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//let rgb = bucket[bucket.length - 1];
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// Take the luma-brightest color in the bucket
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// wrong? bad
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//let rgb = bucket.slice().sort((a, b) => b.luma() - a.luma())[bucket.length - 1];
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// Take the median color in the bucket
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// bad
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//let rgb = bucket[bucket.length >> 1];
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// Combine the brightest of each channel
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@ -745,7 +682,7 @@ function imageToLinearRGB(rgba) {
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rgba[i + 0],
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rgba[i + 1],
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rgba[i + 2]
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).fromSRGB());
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).toLinear());
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}
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return input;
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}
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@ -1,9 +0,0 @@
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ffmpeg \
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-r 60000/1001 \
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-i 'frames/dither-%04d.png' \
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-i 'colamath-audio.wav' \
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-ac 2 \
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-ar 48000 \
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-vf 'pad=w=640:h=360:x=52:y=20' \
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-pix_fmt yuv420p \
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-y colamath-dither.mp4
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@ -1,17 +0,0 @@
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set -a
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mkdir -p frames
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ffmpeg \
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-i colamath-dv.avi \
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-vf 'yadif=1,scale=160:200,crop=h=160' \
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-an \
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-y 'frames/colamath-%04d.png'
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ffmpeg \
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-i colamath-dv.avi \
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-vn \
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-ac 1 \
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-ar 15734 \
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-acodec pcm_u8 \
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-y 'colamath-audio.wav'
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@ -1,15 +0,0 @@
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set -e
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for frame in frames/colamath-[0-9][0-9][0-9][0-9].png
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do
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n="${frame#frames/colamath-}"
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n="${n%.png}"
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out="frames/dither-${n}"
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last="${n:0-1}"
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node ../dither-image.js "$frame" "$out" &
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if (( last == 9 ))
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then
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wait
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fi
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done
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wait
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