Max valid hour is 23, not 24 in PNG tIME chunk

diff --git a/coders/png.c b/coders/png.c
index 0c47fe6d29eb5f308c8330eaefff9f5ec992398b..e4c15fbd8cae4457308ad4ae1bdd45d3268da0e8 100644 (file)
--- a/coders/png.c
+++ b/coders/png.c
@@ -8174,6 +8174,7 @@ static void write_tIME_chunk(Image *image,png_struct *ping,png_info *info,
   if (addhours < 0)
   {
     addhours+=24;
+    addminutes=-addminutes;
     day--;
   }
   hour+=addhours;
@@ -8202,7 +8203,7 @@ static void write_tIME_chunk(Image *image,png_struct *ping,png_info *info,
      hour++;
      minute-=60;
   }
-  if (hour > 24)
+  if (hour > 23)
   {
      day ++;
      hour -=24;