[mapserver-users] differing image size with different mapserver versions

[Even Rouault]

Richard,

your 6.4 image is a interlaced PNG, whereas the 7.6 is a non-interlaced one.

I see in the git history a relevant commit:

$ git show 9984b39cc8f74d60eb240728df660a172a118aad
commit 9984b39cc8f74d60eb240728df660a172a118aad
Author: Thomas Bonfort <thomas.bonfort at gmail.com>
Date:   Sun Oct 5 15:59:44 2008 +0000

     rgba_png: don't interlace by default


     git-svn-id: http://svn.osgeo.org/mapserver/trunk@7960 
7532c77e-422f-0410-93f4-f0b67bdd69e2

diff --git a/maprgbapng.c b/maprgbapng.c
index 105d8d61..c3615edd 100644
--- a/maprgbapng.c
+++ b/maprgbapng.c
@@ -357,10 +357,13 @@ int msSaveImageRGBAQuantized(gdImagePtr img, 
gdIOCtx *ctx, outputFormatObj *form
      int bot_idx, top_idx;
      int remap[256];
      int reqcolors = atoi(msGetOutputFormatOption( format, 
"QUANTIZE_COLORS", "256"));
+    const char *interlace;
      ms_png_info info;
      info.width = gdImageSX(img);
      info.height = gdImageSY(img);
-    if( strcasecmp("ON", msGetOutputFormatOption( format, "INTERLACE", 
"ON" )) == 0 )
+    interlace = msGetOutputFormatOption( format, "INTERLACE", "OFF" );
+    if( strcasecmp("ON", interlace) == 0 || strcasecmp("YES", 
interlace) == 0
+            || strcasecmp("1", interlace) == 0)
          info.interlaced=1;
      else
          info.interlaced=0;

But this predates 6.4 release by several years, so this doesn't explain 
why you see a different behavior, unless something in 6.4 still turned 
on interlacing on in that configuration.

 From what I can see in the doc, the interlacing mode was removed in the 
7.0 release when GD went off, so I don't think you can do much. I guess 
that could be re-added but would require some coding.

Even


Le 15/05/2021 à 17:43, Richard Greenwood a écrit :
> I get significantly different image sizes between MapServer 6.4 and 
> 7.6 with the same output format definition. I've tried many variations 
> of the following.
>
> OUTPUTFORMAT
>   NAME "png-test"
>   DRIVER "AGG/PNG"  # GD driver is same (6.4 only)
>   MIMETYPE "image/png; mode=8bit"
>   IMAGEMODE PC256
>   FORMATOPTION "QUANTIZE_FORCE=on"
>   FORMATOPTION "QUANTIZE_COLORS=256"
>   EXTENSION "png"
>   # TRANSPARENT on or off makes little difference
> END
>
> MapServer 6.4 <https://greenwoodmap.com/mapserv64.png> is 90kB, 
> MapServer 7.6 <https://greenwoodmap.com/mapserv76.png> is 320kB. Any 
> suggestions as to how I can get my MapServer 7.6 image sizes down 
> closer to what I'm getting in MapServer 6.4?
>
> Thanks,
> Rich
>
> -- 
> Richard W. Greenwood, PLS
> www.greenwoodmap.com <http://www.greenwoodmap.com>
>
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/mapserver-users

-- 
http://www.spatialys.com
My software is free, but my time generally not.

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