fix: handle multi-channel TIFF formats and add compression options

Add PDF quality selector (high/medium/low) with JPEG compression.

src/js/utils/tiff-utils.ts

@@ -0,0 +1,45 @@
+type TiffDataArray = Uint8Array | Uint16Array | Float32Array | Float64Array;
+
+export function tiffIfdToRgba(
+  src: TiffDataArray,
+  width: number,
+  height: number,
+  channels: number,
+  photometricType: number
+): Uint8ClampedArray {
+  const totalPixels = width * height;
+  const dst = new Uint8ClampedArray(totalPixels * 4);
+  const isWhiteIsZero = photometricType === 0;
+
+  let maxVal = 255;
+  if (src instanceof Uint16Array) maxVal = 65535;
+  else if (src instanceof Float32Array || src instanceof Float64Array)
+    maxVal = 1;
+
+  const norm = (v: number) => {
+    if (maxVal === 255) return v;
+    if (maxVal === 1) return Math.round(Math.min(1, Math.max(0, v)) * 255);
+    return v >> 8;
+  };
+
+  for (let p = 0; p < totalPixels; p++) {
+    const si = p * channels;
+    const di = p * 4;
+
+    if (channels >= 3) {
+      dst[di] = norm(src[si]);
+      dst[di + 1] = norm(src[si + 1]);
+      dst[di + 2] = norm(src[si + 2]);
+      dst[di + 3] = channels >= 4 ? norm(src[si + 3]) : 255;
+    } else {
+      let gray = norm(src[si]);
+      if (isWhiteIsZero) gray = 255 - gray;
+      dst[di] = gray;
+      dst[di + 1] = gray;
+      dst[di + 2] = gray;
+      dst[di + 3] = channels === 2 ? norm(src[si + 1]) : 255;
+    }
+  }
+
+  return dst;
+}