diff --git a/src/shared/colorspace.js b/src/shared/colorspace.js
index 62f7a4d4f..44a077a78 100644
--- a/src/shared/colorspace.js
+++ b/src/shared/colorspace.js
@@ -639,8 +639,8 @@ var DeviceCmykCS = (function DeviceCmykCSClosure() {
 var CalGrayCS = (function CalGrayCSClosure() {
   function CalGrayCS(whitePoint, blackPoint, gamma) {
     this.name = 'CalGray';
-    this.numComps = 3;
-    this.defaultColor = new Float32Array([0, 0, 0]);
+    this.numComps = 1;
+    this.defaultColor = new Float32Array([0]);
 
     if (!whitePoint) {
       error('WhitePoint missing - required for color space CalGray');
@@ -682,6 +682,33 @@ var CalGrayCS = (function CalGrayCSClosure() {
     }
   }
 
+  function convertToRgb(cs, src, srcOffset, dest, destOffset, scale) {
+    // A represents a gray component of a calibrated gray space.
+    // A <---> AG in the spec
+    var A = src[srcOffset] * scale;
+    var AG = Math.pow(A, cs.G);
+
+    // Computes intermediate variables M, L, N as per spec.
+    // Except if other than default BlackPoint values are used.
+    var M = cs.XW * AG;
+    var L = cs.YW * AG;
+    var N = cs.ZW * AG;
+
+    // Decode XYZ, as per spec.
+    var X = M;
+    var Y = L;
+    var Z = N;
+
+    // http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html, Ch 4.
+    // This yields values in range [0, 100].
+    var Lstar = Math.max(116 * Math.pow(Y, 1 / 3) - 16, 0);
+
+    // Convert values to rgb range [0, 255].
+    dest[destOffset] = Lstar * 255 / 100;
+    dest[destOffset + 1] = Lstar * 255 / 100;
+    dest[destOffset + 2] = Lstar * 255 / 100;
+  }
+
   CalGrayCS.prototype = {
     getRgb: function CalGrayCS_getRgb(src, srcOffset) {
       var rgb = new Uint8Array(3);
@@ -690,41 +717,16 @@ var CalGrayCS = (function CalGrayCSClosure() {
     },
     getRgbItem: function CalGrayCS_getRgbItem(src, srcOffset,
                                               dest, destOffset) {
-      // A represents a gray component of a calibrated gray space.
-      // A <---> AG in the spec
-      var A = src[srcOffset];
-      var AG = Math.pow(A, this.G);
-
-      // Computes intermediate variables M, L, N as per spec.
-      // Except if other than default BlackPoint values are used.
-      var M = this.XW * AG;
-      var L = this.YW * AG;
-      var N = this.ZW * AG;
-
-      // Decode XYZ, as per spec.
-      var X = M;
-      var Y = L;
-      var Z = N;
-
-      // http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html, Ch 4.
-      // This yields values in range [0, 100].
-      var Lstar = Math.max(116 * Math.pow(Y, 1 / 3) - 16, 0);
-
-      // Convert values to rgb range [0, 255].
-      dest[destOffset] = Lstar * 255 / 100;
-      dest[destOffset + 1] = Lstar * 255 / 100;
-      dest[destOffset + 2] = Lstar * 255 / 100;
+      convertToRgb(this, src, srcOffset, dest, destOffset, 1);
     },
     getRgbBuffer: function CalGrayCS_getRgbBuffer(src, srcOffset, count,
                                                   dest, destOffset, bits) {
-      // TODO: This part is copied from DeviceGray. Make this utility function.
-      var scale = 255 / ((1 << bits) - 1);
-      var j = srcOffset, q = destOffset;
+      var scale = 1 / ((1 << bits) - 1);
+
       for (var i = 0; i < count; ++i) {
-        var c = (scale * src[j++]) | 0;
-        dest[q++] = c;
-        dest[q++] = c;
-        dest[q++] = c;
+        convertToRgb(this, src, srcOffset, dest, destOffset, scale);
+        srcOffset += 1;
+        destOffset += 3;
       }
     },
     getOutputLength: function CalGrayCS_getOutputLength(inputLength) {
diff --git a/test/pdfs/issue3903.pdf.link b/test/pdfs/issue3903.pdf.link
new file mode 100644
index 000000000..236f4e21d
--- /dev/null
+++ b/test/pdfs/issue3903.pdf.link
@@ -0,0 +1 @@
+http://www.reloadbench.com/pdf/files/1%20Inch%20Diamonds.pdf
diff --git a/test/test_manifest.json b/test/test_manifest.json
index a3d386b85..4ed58f394 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -76,6 +76,15 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "issue3903",
+       "file": "pdfs/issue3903.pdf",
+       "md5": "c9a4a8012e15cf3b10d671982ce35a92",
+       "rounds": 1,
+       "link": true,
+       "firstPage": 1,
+       "lastPage": 1,
+       "type": "eq"
+    },
     {  "id": "issue2391-1",
       "file": "pdfs/issue2391-1.pdf",
       "md5": "25ae9cb959612e7b343b55da63af2716",