diff --git a/dither-image.js b/dither-image.js
index 2690485..f7be3d4 100644
--- a/dither-image.js
+++ b/dither-image.js
@@ -5,14 +5,18 @@ import {
 import Jimp from 'Jimp';
 
 
-function zeroes(n) {
+function repeat(val, n) {
     let arr = [];
     for (let i = 0; i < n; i++) {
-        arr.push(0);
+        arr.push(val);
     }
     return arr;
 }
 
+function zeroes(n) {
+    return repeat(0, n);
+}
+
 function toLinear(val) {
     // use a 2.4 gamma approximation
     // this is BT.1886 compatible
@@ -584,6 +588,10 @@ function decimate(input, palette, n) {
 
     // preface the reserved bits
     let buckets = reserved.slice().map((c) => [atariRGB[c]]).concat([input.slice()]);
+    if (input.length != 160) {
+        console.log(input.length);
+        throw new Error('xxx bad input size');
+    }
 
     /*
     let buckets = [input.slice()];
@@ -633,6 +641,10 @@ function decimate(input, palette, n) {
     while (buckets.length < n) {
         // Find the bucket with the greatest range in any channel
         let ranges = buckets.map((bucket) => {
+            if (bucket.length == 0) {
+                console.log(buckets);
+                throw new Error('xxx empty bucket');
+            }
             let red   = bucket.map((rgb) => rgb.r);
             let green = bucket.map((rgb) => rgb.g);
             let blue  = bucket.map((rgb) => rgb.b);
@@ -648,16 +660,17 @@ function decimate(input, palette, n) {
         let greatest = 0;
         let index = -1;
         for (let i = 0; i < topRanges.length; i++) {
-            if (topRanges[i] >= greatest) {
+            //if (topRanges[i] >= greatest) {
+            if (topRanges[i] > greatest) {
                 greatest = topRanges[i];
                 index = i;
             }
         }
         if (index == -1) {
             // We just ran out of colors! Pad the buckets.
-            while (buckets.length < n) {
-                buckets.push([new RGB(0, 0, 0)]);
-            }
+            //while (buckets.length < n) {
+            //    buckets.push([new RGB(0, 0, 0)]);
+            //}
             break;
         }
         let [lo, hi] = medianCut(buckets[index], ranges[index]);
@@ -775,19 +788,25 @@ async function loadImage(src) {
 
     let width = image.bitmap.width;
     let height = image.bitmap.height;
-    //if (width != 160 || height != 160) {
-    if (width != 160) {
+
+    let aspect = width / height;
+    let dar = 2 / 1.2;
+    if (aspect > ((320 / 1.2) / 192)) {
+        // wide
         width = 160;
-        //height = 160;
-        //height = 192;
-        let dar = 1.2 / 2;
-        height = (width * image.bitmap.width / image.bitmap.height) * dar;
-        height = Math.round(height);
+        height = Math.round((width * image.bitmap.height / image.bitmap.width) * dar);
         if (height & 1) {
             height++;
         }
-        image = image.resize(width, height);
+    } else {
+        // tall
+        height = 192;
+        width = Math.round((height * image.bitmap.width / image.bitmap.height) / dar);
+        if (width & 1) {
+            width++;
+        }
     }
+    image = image.resize(width, height);
 
     let rgba = image.bitmap.data.slice();
     return {
@@ -823,17 +842,15 @@ async function convert(source) {
         height,
         rgba
     } = await loadImage(source);
+    console.log({width,height});
 
-    if (width !== 160) {
-        throw new Error(`expected 160px-compatible width, got ${width} pixels`);
+    if (width > 160) {
+        throw new Error(`expected <160px width, got ${width} pixels`);
     }
 
-    /*
-    if (height !== 160) {
-        // @fixme support up to 240px
-        throw new Error(`expected 160px height, got ${height} pixels`);
+    if (height > 192) {
+        throw new Error(`expected <192px height, got ${height} pixels`);
     }
-    */
 
     if (rgba.length != width * 4 * height) {
         console.log(`
@@ -860,10 +877,26 @@ async function convert(source) {
         allColors.push(i);
     }
 
+    let left = [], right = [];
+    let padding = 0;
+    if (width < 160) {
+        padding = 160 - width;
+
+        let black = new RGB(0, 0, 0);
+        left = repeat(black, padding >> 1);
+        right = repeat(black, padding + 1 >> 1);
+    }
+
     let lines = [];
     for (let y = 0; y < height; y++) {
         let inputLine = input
             .slice(y * width, (y + 1) * width);
+
+        if (padding) {
+            console.log(`length was ${inputLine.length}`);
+            inputLine = left.concat(inputLine, right);
+            console.log(`length is now ${inputLine.length}`);
+        }
         if (y > 0) {
             let error = lines[y - 1].error;
             inputLine = inputLine.map((rgb, x) => rgb.add(error[x]).clamp());
@@ -872,7 +905,7 @@ async function convert(source) {
         lines.push(line);
     }
     return {
-        width,
+        width: width + padding,
         height,
         lines
     };
@@ -983,7 +1016,7 @@ ${byte2byte(odd(frame.palette3))}
 .align 1024
 displaylist:
     ; 24 lines overscan
-    .repeat 4
+    .repeat 3
         .byte $70 ; 8 blank lines
     .endrep
     ; include a DLI to mark us as frame 0
diff --git a/dither4.s b/dither4.s
index 64a570d..b985633 100644
--- a/dither4.s
+++ b/dither4.s
@@ -34,8 +34,7 @@ bytes_per_line = 40
 pages_per_frame = 32
 lines_per_frame = 262
 ;scanline_offset = 31 + (40 - 24) / 2
-;scanline_offset = 46
-scanline_offset = 46
+scanline_offset = 38
 scanline_max = (lines_per_frame - scanline_offset) / 2
 
 .data