Commit 23d609d28 for imagemagick.org

commit 23d609d285ad1a0b527eb10917424a82fb6c5814
Author: Dirk Lemstra <dirk@lemstra.org>
Date:   Tue Mar 31 19:29:37 2026 +0200

    Use the correct bit depth when reading a PNG bKGD (#8485)

diff --git a/coders/png.c b/coders/png.c
index 4f415602f..97dacd8fa 100644
--- a/coders/png.c
+++ b/coders/png.c
@@ -2818,16 +2818,16 @@ static Image *ReadOnePNGImage(MngReadInfo *mng_info,

         bkgd_scale = 1;

-        if (ping_file_depth == 1)
+        if (ping_bit_depth == 1)
            bkgd_scale = 255;

-        else if (ping_file_depth == 2)
+        else if (ping_bit_depth == 2)
            bkgd_scale = 85;

-        else if (ping_file_depth == 4)
+        else if (ping_bit_depth == 4)
            bkgd_scale = 17;

-        if (ping_file_depth <= 8)
+        if (ping_bit_depth <= 8)
            bkgd_scale *= 257;

         ping_background->red *= (png_uint_16) bkgd_scale;