[vox-tech] Using Convert to Resize Images

[Foo Lim]

On Wed, 19 Feb 2003, Jim Angstadt wrote:

> When I use this syntax:
>    `convert -geometry $geo -quality $qual $from $to`;
> for various values of $qual ( 75 or 85 or 95) there is
> no obvious difference in the 'visual' quality of the
> images.  Also, each comparable file has the same size.
>  And running diff on any two files yields no
> difference.
> 
> So, the files do not seem to be effected by the
> '-quality' option.  Are the quality and geometry
> options mutually exclusive?  What am I missing?

Hi Jim,

I do see a difference.  Here's the listing of my files:

-rw-rw-r--    1 foo        227784 Feb 19 14:43 bbqmap75.jpg
-rw-rw-r--    1 foo        297166 Feb 19 14:44 bbqmap85.jpg
-rw-rw-r--    1 foo        458938 Feb 19 14:44 bbqmap95.jpg
-rw-r--r--    1 foo       1254886 Feb 19 14:42 bbqmap.jpg

after running these commands:

 1014  convert -geometry 50% -quality 75 bbqmap.jpg bbqmap75.jpg
 1016  convert -geometry 50% -quality 85 bbqmap.jpg bbqmap85.jpg
 1017  convert -geometry 50% -quality 95 bbqmap.jpg bbqmap95.jpg

Please post an example run where you see otherwise.

FL