diff --git a/webapp/common.js b/webapp/common.js
new file mode 100644
index 0000000..0739eda
--- /dev/null
+++ b/webapp/common.js
@@ -0,0 +1,57 @@
+/** Shared GeoTIFF → canvas for RGB (≥3 bands) or grayscale (1 band). Requires global GeoTIFF. */
+async function geotiffToCanvasDataUrl(arrayBuffer) {
+ const tiff = await GeoTIFF.fromArrayBuffer(arrayBuffer);
+ const image = await tiff.getImage();
+ const rasters = await image.readRasters();
+ const width = image.getWidth();
+ const height = image.getHeight();
+ const bbox = image.getBoundingBox();
+ const geoKeys = image.getGeoKeys();
+ const crsCode = geoKeys.ProjectedCSTypeGeoKey
+ ? `EPSG:${geoKeys.ProjectedCSTypeGeoKey}`
+ : geoKeys.GeographicTypeGeoKey !== 4326
+ ? `EPSG:${geoKeys.GeographicTypeGeoKey}`
+ : "EPSG:4326";
+ const normalize = (arr) => {
+ let min = Infinity,
+ max = -Infinity;
+ for (const v of arr) if (!isNaN(v) && v > 0) {
+ min = Math.min(min, v);
+ max = Math.max(max, v);
+ }
+ return arr.map((v) => Math.max(0, Math.min(255, ((v - min) / (max - min || 1)) * 255)));
+ };
+ const spp = typeof image.getSamplesPerPixel === "function" ? image.getSamplesPerPixel() : 0;
+ const multi = spp >= 3 || (rasters[1] != null && rasters[2] != null);
+ const b0 = Array.from(rasters[0]);
+ let rN, gN, bN;
+ if (multi) {
+ const blue = b0,
+ green = Array.from(rasters[1]),
+ red = Array.from(rasters[2]);
+ rN = normalize(red);
+ gN = normalize(green);
+ bN = normalize(blue);
+ } else {
+ const g = normalize(b0);
+ rN = g;
+ gN = g;
+ bN = g;
+ }
+ const canvas = Object.assign(document.createElement("canvas"), { width, height });
+ const ctx = canvas.getContext("2d");
+ ctx.imageSmoothingEnabled = false;
+ const imgData = ctx.createImageData(width, height);
+ for (let i = 0; i < rN.length; i++) {
+ const idx = i * 4;
+ if (rN[i] === 0 && gN[i] === 0 && bN[i] === 0) imgData.data[idx + 3] = 0;
+ else {
+ imgData.data[idx] = rN[i];
+ imgData.data[idx + 1] = gN[i];
+ imgData.data[idx + 2] = bN[i];
+ imgData.data[idx + 3] = 255;
+ }
+ }
+ ctx.putImageData(imgData, 0, 0);
+ return { dataUrl: canvas.toDataURL(), bbox, crsCode };
+}
diff --git a/webapp/fusion.html b/webapp/fusion.html
index 22383c3..d3e5879 100644
--- a/webapp/fusion.html
+++ b/webapp/fusion.html
@@ -5,6 +5,7 @@
+
+
+
+
+
+
Metrics
+
+
+
+
+
+
+
+