diff --git a/content/canvas/test/Makefile.in b/content/canvas/test/Makefile.in
index 96b3aae9a96..1404414d537 100644
--- a/content/canvas/test/Makefile.in
+++ b/content/canvas/test/Makefile.in
@@ -81,7 +81,6 @@ _TEST_FILES_0 = \
 	test_2d.composite.uncovered.image.source-in.html \
 	test_2d.composite.uncovered.image.source-out.html \
 	test_2d.drawImage.zerocanvas.html \
-	test_toDataURL_alpha.html \
 	test_toDataURL_lowercase_ascii.html \
 	test_toDataURL_parameters.html \
 	test_mozGetAsFile.html \
diff --git a/content/canvas/test/test_toDataURL_alpha.html b/content/canvas/test/test_toDataURL_alpha.html
deleted file mode 100644
index 3fcece8e2ac..00000000000
--- a/content/canvas/test/test_toDataURL_alpha.html
+++ /dev/null
@@ -1,206 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-<title>Canvas test: toDataURL parameters (Bug 564388)</title>
-<script src="/MochiKit/MochiKit.js"></script>
-<script src="/tests/SimpleTest/SimpleTest.js"></script>
-<link rel="stylesheet" href="/tests/SimpleTest/test.css">
-</head>
-<body>
-<p>
-For image types that do not support an alpha channel, the image must be
-composited onto a solid black background using the source-over operator,
-and the resulting image must be the one used to create the data: URL.
-</p>
-<p> See:
-<a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-canvas-todataurl">
-http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-canvas-todataurl
-</a>
-</p>
-<p>Mozilla
-    <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=650720">Bug 650720</a>
-</p>
-<p class="output">Output:</p>
-<!--
-    Author's note:
-    To add more cases to this test:
-    - To add a row (another color value)
-      * Add a row to the table below, using the canvas id format
-        (c<row>-<col>)
-      * Update runTests to include the new row in the loop
-    - To add a column (another image format)
-      * Add a column to the table below, using the canvas id format above
-      * Update runTests to call do_canvas, passing your column number,
-        the image format, and any options to pass to the toDataUrl function
-
-    Vaguely derived from Philip Taylor's toDataURL.jpeg.alpha test:
-    http://philip.html5.org/tests/canvas/suite/tests/toDataURL.jpeg.alpha.html
--->
-<table>
-    <tr>
-        <th>Type:</th>
-        <th>image/png</th>
-        <th>image/jpeg</th>
-        <th>image/bmp<br />(24 bpp)</th>
-        <th>image/bmp<br />(32 bpp)</th>
-    </tr>
-    <tr>
-        <td id="c1">rgba(128, 255, 128, 0.5)</td>
-        <td><canvas id="c1-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c1-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c1-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c1-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c2">rgba(255, 128, 128, 0.75)</td>
-        <td><canvas id="c2-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c2-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c2-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c2-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c3">rgba(128, 128, 255, 0.25)</td>
-        <td><canvas id="c3-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c3-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c3-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c3-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c4">rgba(255, 255, 255, 1.0)</td>
-        <td><canvas id="c4-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c4-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c4-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c4-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c5">rgba(255, 255, 255, 0)</td>
-        <td><canvas id="c5-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c5-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c5-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c5-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c6">rgba(0, 0, 0, 1.0)</td>
-        <td><canvas id="c6-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c6-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c6-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c6-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-    <tr>
-        <td id="c7">rgba(0, 0, 0, 0)</td>
-        <td><canvas id="c7-1" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c7-2" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c7-3" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-        <td><canvas id="c7-4" class="output" width="100" height="50">
-            <p class="fallback">FAIL (fallback content)</p></canvas></td>
-    </tr>
-</table>
-
-<script>
-var finishedTests = [];
-
-function isPixel(ctx, x,y, r,g,b,a, d)
-{
-    var pos = x + "," + y;
-    var colour = r + "," + g + "," + b + "," + a;
-    var pixel = ctx.getImageData(x, y, 1, 1);
-    var pr = pixel.data[0],
-        pg = pixel.data[1],
-        pb = pixel.data[2],
-        pa = pixel.data[3];
-    ok(r-d <= pr && pr <= r+d &&
-       g-d <= pg && pg <= g+d &&
-       b-d <= pb && pb <= b+d &&
-       a-d <= pa && pa <= a+d,
-       "pixel "+pos+" of "+ctx.canvas.id+" is "+pr+","+pg+","+pb+","+pa+
-         "; expected "+colour+" +/- "+d);
-}
-
-
-function do_canvas(row, col, type, options)
-{
-    finishedTests[row + '_' + col] = false;
-    var canvas = document.getElementById('c' + row + '-' + col);
-    var ctx = canvas.getContext('2d');
-
-    ctx.fillStyle = document.getElementById('c' + row).textContent;
-    ctx.fillRect(0, 0, 100, 50);
-    var data = canvas.toDataURL(type, options);
-    
-    ctx.fillStyle = '#000';
-    ctx.fillRect(0, 0, 100, 50);
-    var img = new Image();
-    
-    var color = document.getElementById('c' + row).textContent;
-    color = color.substr(5, color.length - 6); // strip off the 'argb()'
-    var colors = color.replace(' ', '', 'g').split(',');
-    var r = colors[0]*colors[3],
-        g = colors[1]*colors[3],
-        b = colors[2]*colors[3];
-    
-    img.onload = function ()
-    {
-        ctx.drawImage(img, 0, 0);
-        isPixel(ctx, 50,25, r,g,b,255, 8);
-        finishedTests[row + '_' + col] = true;
-    };
-    img.src = data;
-}
-
-function checkFinished()
-{
-    for (var t in finishedTests) {
-        if (!finishedTests[t]) {
-            setTimeout(checkFinished, 500);
-            return;
-        }
-    }
-    SimpleTest.finish();
-}
-
-function runTests()
-{
-    for (var row = 1; row <= 7; row++) {
-        do_canvas(row, 1, 'image/png');
-        do_canvas(row, 2, 'image/jpeg');
-        do_canvas(row, 3, 'image/bmp');
-        do_canvas(row, 4, 'image/bmp', '-moz-parse-options:bpp=32');
-    }
-
-    setTimeout(checkFinished, 500);
-}
-
-SimpleTest.waitForExplicitFinish();
-
-addLoadEvent(runTests);
-
-</script>
-
-</html>
diff --git a/image/encoders/bmp/nsBMPEncoder.cpp b/image/encoders/bmp/nsBMPEncoder.cpp
index ccc077567d1..64fc2e2c82e 100644
--- a/image/encoders/bmp/nsBMPEncoder.cpp
+++ b/image/encoders/bmp/nsBMPEncoder.cpp
@@ -441,12 +441,15 @@ nsBMPEncoder::ConvertHostARGBRow(const PRUint8* aSrc, PRUint8* aDest,
     PRUint8 *pixelOut = &aDest[x * BytesPerPixel(mBMPInfoHeader.bpp)];
 
     PRUint8 alpha = (pixelIn & 0xff000000) >> 24;
-    pixelOut[0] = (((pixelIn & 0xff0000) >> 16));
-    pixelOut[1] = (((pixelIn & 0x00ff00) >>  8));
-    pixelOut[2] = (((pixelIn & 0x0000ff) >>  0));
-
-    if (mBMPInfoHeader.bpp == 32) {
-      pixelOut[3] = alpha;
+    if (alpha == 0) {
+      pixelOut[0] = pixelOut[1] = pixelOut[2] = 0;
+    } else {
+      pixelOut[0] = (((pixelIn & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+      pixelOut[1] = (((pixelIn & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
+      pixelOut[2] = (((pixelIn & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
+      if(mBMPInfoHeader.bpp == 32) {
+        pixelOut[3] = alpha;
+      }
     }
   }
 }
diff --git a/image/encoders/jpeg/nsJPEGEncoder.cpp b/image/encoders/jpeg/nsJPEGEncoder.cpp
index 5744572dd86..4d199dad3be 100644
--- a/image/encoders/jpeg/nsJPEGEncoder.cpp
+++ b/image/encoders/jpeg/nsJPEGEncoder.cpp
@@ -365,9 +365,14 @@ nsJPEGEncoder::ConvertHostARGBRow(const PRUint8* aSrc, PRUint8* aDest,
     const PRUint32& pixelIn = ((const PRUint32*)(aSrc))[x];
     PRUint8 *pixelOut = &aDest[x * 3];
 
-    pixelOut[0] = (((pixelIn & 0xff0000) >> 16));
-    pixelOut[1] = (((pixelIn & 0x00ff00) >>  8));
-    pixelOut[2] = (((pixelIn & 0x0000ff) >>  0));
+    PRUint8 alpha = (pixelIn & 0xff000000) >> 24;
+    if (alpha == 0) {
+      pixelOut[0] = pixelOut[1] = pixelOut[2] = 0;
+    } else {
+      pixelOut[0] = (((pixelIn & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+      pixelOut[1] = (((pixelIn & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
+      pixelOut[2] = (((pixelIn & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
+    }
   }
 }
 

Type:	image/png	image/jpeg	image/bmp (24 bpp)	image/bmp (32 bpp)
rgba(128, 255, 128, 0.5)
rgba(255, 128, 128, 0.75)
rgba(128, 128, 255, 0.25)
rgba(255, 255, 255, 1.0)
rgba(255, 255, 255, 0)
rgba(0, 0, 0, 1.0)
rgba(0, 0, 0, 0)