Fixed bug with scaling background while writing sub-8-bit grayscale images.

diff --git a/coders/png.c b/coders/png.c
index f908090a6d725aaa79a87251fec388989ea669c3..2d8abe9fd6b54cd8fa940f732b52be90b767f523 100644 (file)
--- a/coders/png.c
+++ b/coders/png.c
@@ -9664,9 +9664,9 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
          if (ping_exclude_bKGD == MagickFalse)
          {
 
-         ping_background.gray=(png_uint_16)
-           ((maxval/255.)*((GetPixelInfoIntensity(&image->background_color)))
-                                    +.5);
+         ping_background.gray=(png_uint_16) ((maxval/65535.)*
+           (ScaleQuantumToShort(((GetPixelInfoIntensity(
+           &image->background_color))) +.5)));
 
          if (logging != MagickFalse)
            (void) LogMagickEvent(CoderEvent,GetMagickModule(),