cleaner handling of reserved colors

dither-image.js

@@ -580,7 +580,11 @@ function decimate(input, palette, n) {
 
     // Median cut!
     // https://en.wikipedia.org/wiki/Median_cut
-    let buckets = [input.slice()];
+    //let buckets = [input.slice()];
+
+    // preface the reserved bits
+    let buckets = reserved.slice().map((c) => [atariRGB[c]]).concat([input.slice()]);
+
     let medianCut = (bucket, range) => {
         if (bucket.length < 2) {
             console.log(bucket);

video/combine.sh

@@ -4,6 +4,6 @@ ffmpeg \
     -i 'colamath-audio.wav' \
     -ac 2 \
     -ar 48000 \
-    -vf 'pad=w=640:h=480:x=52:y=80' \
+    -vf 'pad=w=640:h=360:x=52:y=20' \
     -pix_fmt yuv420p \
     -y colamath-dither.mp4