--- a/ImageReader.st	Sat Mar 05 15:24:06 2016 +0100
+++ b/ImageReader.st	Sat Mar 05 15:24:58 2016 +0100
@@ -1228,6 +1228,64 @@
     "Modified: 23.4.1997 / 18:54:05 / cg"
 !
 
+swap:count pixelsFromRGB_to_BGR_in:data startingAt:startIndex bytesPerPixel:bpp
+    "swap bytes from RGB into BGR order.
+     The argument is a pixel data buffer (byteArray).
+     Can be used for both 24bit rgb data (bpp=3) or rgba data (bpp=4)"
+
+    |t idx|
+
+%{  /* OPTIONAL */
+    if (__isByteArray(data)
+     && __isSmallInteger(count)
+     && __isSmallInteger(startIndex)
+     && __isSmallInteger(bpp)) {
+	INT __count = __intVal(count);
+	INT __startOffset = __intVal(startIndex) - 1;
+	INT __dataSize = __byteArraySize(data);
+	int __bpp = __intVal(bpp);
+	INT __nBytes = __count * __bpp;
+
+	if ((__startOffset + __nBytes) <= __dataSize) {
+	    unsigned char *__cp = __ByteArrayInstPtr(data)->ba_element + __startOffset;
+
+	    while (__count-- > 0) {
+		unsigned char __t;
+
+		__t = __cp[0];
+		__cp[0] = __cp[2];
+		__cp[2] = __t;
+		__cp += __bpp;
+	    }
+	    RETURN (self);
+	}
+    }
+%}.
+    idx := startIndex.
+    1 to:count do:[:i |
+	t := data at:idx.
+	data at:idx put:(data at:idx+2).
+	data at:idx+2 put:t.
+	idx := idx + bpp.
+    ].
+
+    "
+     |bytes|
+
+     bytes := #[ 0 1 2  3 4 5  6 7 8  9 ].
+     self swap:2 pixelsFromRGB_to_BGR_in:bytes startingAt:1 bytesPerPixel:3.
+     bytes.
+    "
+
+    "
+     |bytes|
+
+     bytes := #[ 0 1 2 3  4 5 6 7  8 9 ].
+     self swap:2 pixelsFromRGB_to_BGR_in:bytes startingAt:1 bytesPerPixel:4.
+     bytes.
+    "
+!
+
 swap:nBytes bytesFromRGB_to_BGR_in:data
     "swap bytes from RGB into BGR order.
      The argument is a pixel data buffer (byteArray)"
@@ -2195,4 +2253,3 @@
 version_CVS
     ^ '$Header$'
 ! !
-