diff --git a/poppler/JPEG2000Stream.cc b/poppler/JPEG2000Stream.cc
index d52f088..08e5055 100644
--- a/poppler/JPEG2000Stream.cc
+++ b/poppler/JPEG2000Stream.cc
@@ -17,6 +17,7 @@ JPXStream::JPXStream(Stream *strA) : FilterStream(strA)
   inited = gFalse;
   image = NULL;
   dinfo = NULL;
+  npixels = 0;
 }
 
 JPXStream::~JPXStream() {
@@ -32,6 +33,7 @@ void JPXStream::close() {
   if (image != NULL) {
     opj_image_destroy(image);
     image = NULL;
+    npixels = 0;
   }
   if (dinfo != NULL) {
     opj_destroy_decompress(dinfo);
@@ -73,6 +75,38 @@ void JPXStream::init()
   init2(buf, length, CODEC_JP2);
   free(buf);
 
+  if (image) {
+    data = (unsigned char *)image->comps[0].data;
+    npixels = image->comps[0].w * image->comps[0].h;
+    int ncomps = image->numcomps < 4 ? image->numcomps : 4;
+    for (int component = 0; component < ncomps; component++) {
+      if (image->comps[component].data == NULL) {
+	close();
+	break;
+      }
+      int adjust = 0;
+      unsigned char *cdata = data + component;
+      if (image->comps[component].prec > 8)
+	adjust = image->comps[component].prec - 8;
+      int sgndcorr = 0;
+      if (image->comps[component].sgnd)
+	sgndcorr = 1 << (image->comps[0].prec - 1);
+      for (int i = 0; i < npixels; i++) {
+	int r = image->comps[component].data[i];
+	r += sgndcorr;
+	if (adjust) {
+	  r = (r >> adjust)+((r >> (adjust-1))%2);
+	  if (unlikely(r > 255))
+	    r = 255;
+	}
+	*cdata = r;
+	cdata += ncomps;
+      }
+    }
+    npixels *= ncomps;
+  } else
+    npixels = 0;
+
   counter = 0;
   inited = gTrue;
 }
diff --git a/poppler/JPEG2000Stream.h b/poppler/JPEG2000Stream.h
index bda2721..08449b0 100644
--- a/poppler/JPEG2000Stream.h
+++ b/poppler/JPEG2000Stream.h
@@ -49,37 +49,18 @@ private:
   }
 
   inline int doLookChar() {
-    if (inited == gFalse) init();
+    if (unlikely(inited == gFalse)) init();
 
-    if (!image) return EOF;
+    if (unlikely(counter >= npixels)) return EOF;
 
-    int w = image->comps[0].w;
-    int h = image->comps[0].h;
-
-    int y = (counter / image->numcomps) / w;
-    int x = (counter / image->numcomps) % w;
-    if (y >= h) return EOF;
-
-    int component = counter % image->numcomps;
-
-    int adjust = 0;
-    if (image->comps[component].prec > 8) {
-      adjust = image->comps[component].prec - 8;
-    }
-
-    if (unlikely(image->comps[component].data == NULL)) return EOF;
-
-    int r = image->comps[component].data[y * w + x];
-    r += (image->comps[component].sgnd ? 1 << (image->comps[0].prec - 1) : 0);
-
-    unsigned char rc = (unsigned char) ((r >> adjust)+((r >> (adjust-1))%2));
-
-    return rc;
+    return data[counter];
   }
 
   opj_image_t *image;
   opj_dinfo_t *dinfo;
+  unsigned char *data;
   int counter;
+  int npixels;
   GBool inited;
 };