From: glennrp <glennrp@git.imagemagick.org>
Date: Thu, 15 Dec 2011 12:20:50 +0000 (+0000)
Subject: Fixed bug with scaling background while writing sub-8-bit grayscale images.
X-Git-Tag: 7.0.1-0~6535
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9f0fa85ee29d661f91aab1275659f6690551069b;p=imagemagick

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

diff --git a/coders/png.c b/coders/png.c
index f908090a6..2d8abe9fd 100644
--- 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(),