$OpenBSD: patch-src_kernel_qpngio_cpp,v 1.2 2007/03/31 22:49:46 espie Exp $ --- src/kernel/qpngio.cpp.orig Thu Oct 19 16:25:20 2006 +++ src/kernel/qpngio.cpp Sat Mar 31 14:51:24 2007 @@ -110,10 +110,18 @@ void CALLBACK_CALL_TYPE qpiw_flush_fn( png_structp png 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;