radiant: redo 6011367, fix alpha channel for tRNS cheap transparency PNG

diff --git a/plugins/imagepng/plugin.cpp b/plugins/imagepng/plugin.cpp
index 281193fd63afd1208a1d37128912da151b687f77..4bdf2b0a9833d9c1ca7d7d3e902e25f739a4de47 100644 (file)
--- a/plugins/imagepng/plugin.cpp
+++ b/plugins/imagepng/plugin.cpp
@@ -113,7 +113,7 @@ Image* LoadPNGBuff( unsigned char* fbuffer ){
                png_set_tRNS_to_alpha( png_ptr );
        }
 
-       if ( !( color_type & PNG_COLOR_MASK_ALPHA ) ) {
+       else if ( !( color_type & PNG_COLOR_MASK_ALPHA ) ) {
                // Set the background color to draw transparent and alpha images over.
                png_color_16 my_background, *image_background;