Comments in generated JPEGs
Frank Warmerdam
warmerdam at POBOX.COM
Thu Jun 22 07:23:50 PDT 2006
Stephen Davies wrote:
> My latest addition to my Mapserver application is a 3G phone interface.
>
> However, it seems that at least the Motorola 3vx phone cannot handle
> comments in JPEG images.
>
> The images generated by Mapserver/gd have the comment:
> CREATOR:gd-jpeg V1.0 (using IJG JPEG v62), quality=80
> and the phone refuses to display them.
> If I manually remove the comment with gimp, the images display
> perfectly.
>
> Does anybody know how to stop Mapserver/gd from including the comment?
Stephen,
As far as I know, you would need to patch the version of GD you are using.
If you look in GD's gd_jpeg.c file you should see a code segment like:
jpeg_start_compress (&cinfo, TRUE);
sprintf (comment, "CREATOR: gd-jpeg v%s (using IJG JPEG v%d),",
GD_JPEG_VERSION, JPEG_LIB_VERSION);
if (quality >= 0)
sprintf (comment + strlen (comment), " quality = %d\n", quality);
else
strcat (comment + strlen (comment), " default quality\n");
jpeg_write_marker (&cinfo, JPEG_COM, (unsigned char *) comment,
(unsigned int) strlen (comment));
if (im->trueColor)
{
...
try changing this to:
jpeg_start_compress (&cinfo, TRUE);
if (im->trueColor)
{
...
Quite a lame "feature" of the phone if you were to ask me!
Good luck,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | President OSGF, http://osgeo.org
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