hmm not half bad

dither-image.js

@@ -540,10 +540,15 @@ function decimate(input, palette, n, inputError, y) {
 
     // Median cut!
     // https://en.wikipedia.org/wiki/Median_cut
-    //let buckets = [input.slice()];
+    let buckets = [input.slice()];
-    let initial = dither(palette);
+    //let initial = dither(palette);
-    let buckets = [initial.output.map((i) => atariRGB[palette[i]])];
+    //let buckets = [initial.output.map((i) => atariRGB[palette[i]])];
     let medianCut = (bucket, range) => {
+        if (bucket.length < 2) {
+            console.log(bucket);
+            throw new Error('short bucket');
+        }
+        //console.log('medianCut', bucket, range);
         // Sort by the channel with the greatest range,
         // then cut the bucket in two at the median.
         if (range.g >= range.r && range.g >= range.b) {
@@ -554,6 +559,7 @@ function decimate(input, palette, n, inputError, y) {
             bucket.sort((a, b) => b.b - a.b);
         }
         let half = bucket.length >> 1;
+        //console.log('cutting', half, bucket.length);
         return [bucket.slice(0, half), bucket.slice(half)];
     };
     while (buckets.length < n) {
@@ -580,8 +586,24 @@ function decimate(input, palette, n, inputError, y) {
         //    .reduce((acc, rgb) => acc.inc(rgb), new RGB(0, 0, 0))
         //    .divide(bucket.length);
         
+        // scale to the max luma
+        let lumas = bucket.map((rgb) => rgb.luma());
+        console.log(lumas);
+        let luma = Math.max(...lumas);
+        let rgb = bucket[lumas.indexOf(luma)];
+        console.log(rgb, luma);
+        let from = rgb.luma();
+        if (from > 0) {
+            rgb = rgb.multiply(luma / rgb.luma());
+        }
+        console.log(rgb, luma);
+        if (!rgb) {
+            throw new Error('xxx');
+        }
+
         // Take the channel-brightest color in the bucket
-        //let rgb = bucket[bucket.length - 1];
+        // bad
+        //rgb = bucket[bucket.length - 1];
 
         // Take the luma-brightest color in the bucket
         //let rgb = bucket.slice().sort((a, b) => b.luma() - a.luma())[bucket.length - 1];
@@ -591,11 +613,22 @@ function decimate(input, palette, n, inputError, y) {
 
         // Combine the brightest of each channel
         // this is kinda good
+        /*
         let rgb = new RGB(
             Math.max(...bucket.map((rgb) => rgb.r)),
             Math.max(...bucket.map((rgb) => rgb.g)),
             Math.max(...bucket.map((rgb) => rgb.b))
         );
+        */
+        // combine the median of each channel
+        // sux
+        /*
+        let rgb = new RGB(
+            bucket.map((rgb) => rgb.r).sort((a, b) => b - a)[bucket.length >> 1],
+            bucket.map((rgb) => rgb.g).sort((a, b) => b - a)[bucket.length >> 1],
+            bucket.map((rgb) => rgb.b).sort((a, b) => b - a)[bucket.length >> 1]
+        );
+        */
 
         // Take the luma-median color in the bucket
         //let rgb = bucket.slice().sort((a, b) => b.luma() - a.luma())[bucket.length >> 1];
@@ -605,14 +638,14 @@ function decimate(input, palette, n, inputError, y) {
         //    .sort((a, b) => Math.max(b.r, b.g, b.b) - Math.max(a.r, b.g, b.b))[bucket.length >> 1];
 
         // And map into the Atari palette
-        let dists = palette.map((   i) => rgb.difference(atariRGB[i]).magnitude());
+        let dists = palette.map((i) => rgb.difference(atariRGB[i]).magnitude());
         let closest = Math.min(...dists);
         let index = dists.indexOf(closest);
         return palette[index];
     });
     // hack
     decimated.sort((a, b) => a - b);
-    console.log(decimated);
+    //console.log(decimated);
     decimated[0] = 0;
 
     // Palette fits