--- qt-x11-free-3.3.5/src/kernel/qpngio.cpp.orig	Fri Feb 10 14:45:53 2006
+++ qt-x11-free-3.3.5/src/kernel/qpngio.cpp	Fri Feb 10 14:48:05 2006
@@ -110,10 +110,18 @@
 static
 void setup_qt( QImage& image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0 )
 {
-    if ( screen_gamma != 0.0 && png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) ) {
+    if ( 0.0 == screen_gamma )
+	// PNG docs say this is a good guess for a PC monitor
+        // in a dark room
+	screen_gamma = 2.2;
+    if ( png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) ) {
+	// the file has a gAMA attribute
 	double file_gamma;
-	png_get_gAMA(png_ptr, info_ptr, &file_gamma);
-	png_set_gamma( png_ptr, screen_gamma, file_gamma );
+	if ( png_get_gAMA(png_ptr, info_ptr, &file_gamma))
+	    png_set_gamma( png_ptr, screen_gamma, file_gamma );
+    } else {
+	// no file gamma, use a reasonable default
+	png_set_gamma( png_ptr, screen_gamma, 0.45455 );
     }
 
     png_uint_32 width;