Fix the new transparency logic in the Q8 case

diff --git a/coders/png.c b/coders/png.c
index 5b08196e5727850ca55bc8a832e5723393a12b2f..686a3fa99347c434a2bef532f2089a07e9e3ae54 100644 (file)
--- a/coders/png.c
+++ b/coders/png.c
@@ -2240,8 +2240,8 @@ static Image *ReadOnePNGImage(MngInfo *mng_info,
 #if (MAGICKCORE_QUANTUM_DEPTH == 8)  /* This needs testing. */
               else /* Reducing tRNS values from 16 to 8 merges some values */
                 transparent_color.opacity=(Quantum) (
-                    ping_trans_color->gray *
-                    (((1UL << ping_bit_depth)-1)/QuantumRange));
+                    (ping_trans_color->gray *
+                    QuantumRange)/((1UL << ping_bit_depth)-1));
 #endif
               if (logging != MagickFalse)
               {