diff --git a/index.html b/index.html
index 4b51935..18d1f51 100644
--- a/index.html
+++ b/index.html
@@ -24,6 +24,9 @@
         <div>
             <canvas id="work" width="80" height="160" class="stretchy"></canvas>
         </div>
+        <div>
+            <span id="block-count">n/a</span> blocks per frame
+        </div>
 
         <script type="text/javascript">
             let width = 80;
@@ -77,12 +80,41 @@
                 }
 
                 let blocks = [];
-                for (let y = 0; y < height / blockHeight; y++) {
-                    for (let x = 0; x < width / blockWidth; x++) {
-                        let i = y * (width / blockWidth) + x;
+                let chars = new Uint16Array(widthBlocks * heightBlocks);
+                for (let n = 0, y = 0; y < heightBlocks; y++) {
+                    for (let x = 0; x < widthBlocks; x++, n++) {
+                        let i = y * widthBlocks + x;
+                        blocks[i] = new Uint8Array(blockWidth * blockHeight);
+                        chars[n] = i;
+                        for (let yy = 0; yy < blockHeight; yy++) {
+                            for (let xx = 0; xx < blockWidth; xx++) {
+                                let ii = yy * blockWidth + xx;
+                                blocks[i][ii] = pixels[(y * blockHeight + yy) * width + (x * blockWidth + xx)];
+                            }
+                        }
                     }
                 }
 
+                // Now we have 800 blocks for 80x160 image
+                // But we can only use 128 + their mirror images
+                //
+                // First pass: sort.
+                let zero = "0".charCodeAt(0);
+                // Convert the 4bpp pixel indices into hex strings
+                let blockMap = {};
+                let keys = [];
+                for (let i = 0; i < blocks.length; i++) {
+                    let key = blocks[i].map((n) => n.toString(16)).join('');
+                    console.log(key);
+                    if (!blockMap[key]) {
+                        blockMap[key] = blocks[i];
+                        keys.push(blockMap[key]);
+                    }
+                }
+                let span = document.querySelector('#block-count');
+                span.textContent = `${keys.length}`;
+
+
                 for (let y = 0; y < height; y++) {
                     for (let x = 0; x < width; x++) {
                         let i = y * width + x;