Some jpx images can have a mask

It fixes #18896.

Author: calixteman

src/core/colorspace.js

@@ -15,6 +15,7 @@
 
 import {
   assert,
+  FeatureTest,
   FormatError,
   info,
   shadow,
@@ -60,6 +61,61 @@ function resizeRgbImage(src, dest, w1, h1, w2, h2, alpha01) {
   }
 }
 
+function resizeRgbaImage(src, dest, w1, h1, w2, h2, alpha01) {
+  const xRatio = w1 / w2;
+  const yRatio = h1 / h2;
+  let newIndex = 0;
+  const xScaled = new Uint16Array(w2);
+
+  if (alpha01 === 1) {
+    for (let i = 0; i < w2; i++) {
+      xScaled[i] = Math.floor(i * xRatio);
+    }
+    const src32 = new Uint32Array(src.buffer);
+    const dest32 = new Uint32Array(dest.buffer);
+    const rgbMask = FeatureTest.isLittleEndian ? 0x00ffffff : 0xffffff00;
+    for (let i = 0; i < h2; i++) {
+      const buf = src32.subarray(Math.floor(i * yRatio) * w1);
+      for (let j = 0; j < w2; j++) {
+        dest32[newIndex++] |= buf[xScaled[j]] & rgbMask;
+      }
+    }
+  } else {
+    const COMPONENTS = 4;
+    const w1Scanline = w1 * COMPONENTS;
+    for (let i = 0; i < w2; i++) {
+      xScaled[i] = Math.floor(i * xRatio) * COMPONENTS;
+    }
+    for (let i = 0; i < h2; i++) {
+      const buf = src.subarray(Math.floor(i * yRatio) * w1Scanline);
+      for (let j = 0; j < w2; j++) {
+        const oldIndex = xScaled[j];
+        dest[newIndex++] = buf[oldIndex];
+        dest[newIndex++] = buf[oldIndex + 1];
+        dest[newIndex++] = buf[oldIndex + 2];
+      }
+    }
+  }
+}
+
+function copyRgbaImage(src, dest, alpha01) {
+  if (alpha01 === 1) {
+    const src32 = new Uint32Array(src.buffer);
+    const dest32 = new Uint32Array(dest.buffer);
+    const rgbMask = FeatureTest.isLittleEndian ? 0x00ffffff : 0xffffff00;
+    for (let i = 0, ii = src32.length; i < ii; i++) {
+      dest32[i] |= src32[i] & rgbMask;
+    }
+  } else {
+    let j = 0;
+    for (let i = 0, ii = src.length; i < ii; i += 4) {
+      dest[j++] = src[i];
+      dest[j++] = src[i + 1];
+      dest[j++] = src[i + 2];
+    }
+  }
+}
+
 class ColorSpace {
   constructor(name, numComps) {
     if (
@@ -806,6 +862,32 @@ class DeviceRgbaCS extends ColorSpace {
   isPassthrough(bits) {
     return bits === 8;
   }
+
+  fillRgb(
+    dest,
+    originalWidth,
+    originalHeight,
+    width,
+    height,
+    actualHeight,
+    bpc,
+    comps,
+    alpha01
+  ) {
+    if (originalHeight !== height || originalWidth !== width) {
+      resizeRgbaImage(
+        comps,
+        dest,
+        originalWidth,
+        originalHeight,
+        width,
+        height,
+        alpha01
+      );
+    } else {
+      copyRgbaImage(comps, dest, alpha01);
+    }
+  }
 }
 
 /**

src/core/image.js

@@ -705,7 +705,7 @@ class PDFImage {
       isOffscreenCanvasSupported &&
       ImageResizer.needsToBeResized(drawWidth, drawHeight);
 
-    if (this.colorSpace.name === "DeviceRGBA") {
+    if (!this.mask && this.colorSpace.name === "DeviceRGBA") {
       imgData.kind = ImageKind.RGBA_32BPP;
       const imgArray = (imgData.data = await this.getImageBytes(
         originalHeight * originalWidth * 4,

test/pdfs/issue18896.pdf.link

@@ -0,0 +1 @@
+https://github.com/user-attachments/files/17365176/issue18896.pdf

test/test_manifest.json

@@ -10700,5 +10700,14 @@
     "rounds": 1,
     "type": "eq",
     "talos": false
+  },
+  {
+    "id": "issue18896",
+    "file": "pdfs/issue18896.pdf",
+    "md5": "4acb4df0f38c976dce5e841e6de1f875",
+    "rounds": 1,
+    "type": "eq",
+    "link": true,
+    "talos": false
   }
 ]