Fix where image component decoding takes place.

src/image.js

@@ -49,7 +49,7 @@ var PDFImage = (function PDFImageClosure() {
     // Clamp the value to the range
     return value < 0 ? 0 : value > max ? max : value;
   }
-  function PDFImage(xref, res, image, inline, smask, mask) {
+  function PDFImage(xref, res, image, inline, smask, mask, isMask) {
     this.image = image;
     if (image.getParams) {
       // JPX/JPEG2000 streams directly contain bits per component
@@ -95,8 +95,9 @@ var PDFImage = (function PDFImageClosure() {
 
     this.decode = dict.get('Decode', 'D');
     this.needsDecode = false;
-    if (this.decode && this.colorSpace &&
-        !this.colorSpace.isDefaultDecode(this.decode)) {
+    if (this.decode &&
+        ((this.colorSpace && !this.colorSpace.isDefaultDecode(this.decode)) ||
+         (isMask && !ColorSpace.isDefaultDecode(this.decode, 1)))) {
       this.needsDecode = true;
       // Do some preprocessing to avoid more math.
       var max = (1 << bitsPerComponent) - 1;
@@ -114,7 +115,7 @@ var PDFImage = (function PDFImageClosure() {
       this.smask = new PDFImage(xref, res, smask, false);
     } else if (mask) {
       if (isStream(mask)) {
-        this.mask = new PDFImage(xref, res, mask, false);
+        this.mask = new PDFImage(xref, res, mask, false, null, null, true);
       } else {
         // Color key mask (just an array).
         this.mask = mask;
@@ -216,13 +217,37 @@ var PDFImage = (function PDFImageClosure() {
         return this.height;
       return Math.max(this.height, this.smask.height);
     },
+    decodeBuffer: function PDFImage_decodeBuffer(buffer) {
+      var bpc = this.bpc;
+      var decodeMap = this.decode;
+      var numComps = this.numComps;
+
+      var decodeAddends, decodeCoefficients;
+      var decodeAddends = this.decodeAddends;
+      var decodeCoefficients = this.decodeCoefficients;
+      var max = (1 << bpc) - 1;
+
+      if (bpc === 1) {
+        // If the buffer needed decode that means it just needs to be inverted.
+        for (var i = 0, ii = buffer.length; i < ii; i++) {
+          buffer[i] = +!(buffer[i]);
+        }
+        return;
+      }
+      var index = 0;
+      for (var i = 0, ii = this.width * this.height; i < ii; i++) {
+        for (var j = 0; j < numComps; j++) {
+          buffer[index] = decodeAndClamp(buffer[index], decodeAddends[j],
+                                            decodeCoefficients[j], max);
+          index++;
+        }
+      }
+    },
     getComponents: function PDFImage_getComponents(buffer) {
       var bpc = this.bpc;
-      var needsDecode = this.needsDecode;
-      var decodeMap = this.decode;
 
       // This image doesn't require any extra work.
-      if (bpc == 8 && !needsDecode)
+      if (bpc === 8)
         return buffer;
 
       var bufferLength = buffer.length;
@@ -235,29 +260,11 @@ var PDFImage = (function PDFImageClosure() {
       var output = bpc <= 8 ? new Uint8Array(length) :
         bpc <= 16 ? new Uint16Array(length) : new Uint32Array(length);
       var rowComps = width * numComps;
-      var decodeAddends, decodeCoefficients;
-      if (needsDecode) {
-        decodeAddends = this.decodeAddends;
-        decodeCoefficients = this.decodeCoefficients;
-      }
+
       var max = (1 << bpc) - 1;
 
-      if (bpc == 8) {
-        // Optimization for reading 8 bpc images that have a decode.
-        for (var i = 0, ii = length; i < ii; ++i) {
-          var compIndex = i % numComps;
-          var value = buffer[i];
-          value = decodeAndClamp(value, decodeAddends[compIndex],
-                          decodeCoefficients[compIndex], max);
-          output[i] = value;
-        }
-      } else if (bpc == 1) {
+      if (bpc === 1) {
         // Optimization for reading 1 bpc images.
-        var valueZero = 0, valueOne = 1;
-        if (decodeMap) {
-          valueZero = decodeMap[0] ? 1 : 0;
-          valueOne = decodeMap[1] ? 1 : 0;
-        }
         var mask = 0;
         var buf = 0;
 
@@ -274,7 +281,7 @@ var PDFImage = (function PDFImageClosure() {
             mask = 128;
           }
 
-          output[i] = !(buf & mask) ? valueZero : valueOne;
+          output[i] = +!!(buf & mask);
         }
       } else {
         // The general case that handles all other bpc values.
@@ -292,12 +299,7 @@ var PDFImage = (function PDFImageClosure() {
 
           var remainingBits = bits - bpc;
           var value = buf >> remainingBits;
-          if (needsDecode) {
-            var compIndex = i % numComps;
-            value = decodeAndClamp(value, decodeAddends[compIndex],
-                            decodeCoefficients[compIndex], max);
-          }
-          output[i] = value;
+          output[i] = value < 0 ? 0 : value > max ? max : value;
           buf = buf & ((1 << remainingBits) - 1);
           bits = remainingBits;
         }
@@ -397,21 +399,27 @@ var PDFImage = (function PDFImageClosure() {
       // imgArray can be incomplete (e.g. after CCITT fax encoding)
       var actualHeight = 0 | (imgArray.length / rowBytes *
                          height / originalHeight);
+      var comps = this.getComponents(imgArray);
+      // Build opacity here since color key masking needs to be perormed on
+      // undecoded values.
+      var opacity = this.getOpacity(width, height, comps);
 
-      var comps = this.colorSpace.createRgbBuffer(this.getComponents(imgArray),
-        0, originalWidth * originalHeight, bpc);
+      if (this.needsDecode) {
+        this.decodeBuffer(comps);
+      }
+      var rgbBuf = this.colorSpace.createRgbBuffer(comps, 0,
+                                    originalWidth * originalHeight, bpc);
       if (originalWidth != width || originalHeight != height)
-        comps = PDFImage.resize(comps, this.bpc, 3, originalWidth,
+        rgbBuf = PDFImage.resize(rgbBuf, this.bpc, 3, originalWidth,
                                 originalHeight, width, height);
       var compsPos = 0;
-      var opacity = this.getOpacity(width, height, imgArray);
       var opacityPos = 0;
       var length = width * actualHeight * 4;
 
       for (var i = 0; i < length; i += 4) {
-        buffer[i] = comps[compsPos++];
-        buffer[i + 1] = comps[compsPos++];
-        buffer[i + 2] = comps[compsPos++];
+        buffer[i] = rgbBuf[compsPos++];
+        buffer[i + 1] = rgbBuf[compsPos++];
+        buffer[i + 2] = rgbBuf[compsPos++];
         buffer[i + 3] = opacity[opacityPos++];
       }
     },
@@ -429,6 +437,9 @@ var PDFImage = (function PDFImageClosure() {
       var imgArray = this.getImageBytes(height * rowBytes);
 
       var comps = this.getComponents(imgArray);
+      if (this.needsDecode) {
+        this.decodeBuffer(comps);
+      }
       var length = width * height;
       // we aren't using a colorspace so we need to scale the value
       var scale = 255 / ((1 << bpc) - 1);

test/pdfs/issue2770.pdf.link

@@ -0,0 +1 @@
+https://bugzilla.mozilla.org/attachment.cgi?id=718826

test/test_manifest.json

@@ -971,6 +971,14 @@
       "link": true,
       "type": "eq"
     },
+    {  "id": "issue2770",
+      "file": "pdfs/issue2770.pdf",
+      "md5": "36070d756d06eaa35c2227efb069fb1b",
+      "rounds": 1,
+      "link": true,
+      "type": "eq",
+      "about": "Has a 4 bit per component image with mask and decode."
+    },
     {  "id": "p020121130574743273239",
       "file": "pdfs/P020121130574743273239.pdf",
       "md5": "271b65885d42d174cbc597ca89becb1a",