[magick-users] JPG compression levels

[Yuval Levy]

Thank you, Anthony and Wolfgang. I solved the issue.

Wolfgang Hugemann wrote:
> There is a really nice visualisation of the single steps in JPEG Com
> pression (deplorably only in German, but you'll get through it, I guess)
> at http://www.spemaus.de/studium/visjpeg/applet.html

wow! amazing! i have not gone through all of it but it is of excellent
educational value (and it gave me a chance to refresh my Deutsch).


Anthony Thyssen wrote:
> | specifically I would like the edges of an image to not be compressed
> | at all.
> |
> I dodn't even know that was posible with the JPEG format!
> I doubt IM convert (which calls the libjpeg library) will do that.


the solution:
* produce two versions of the same image with ImageMagick, one at
quality 100 and the other at quality 60
* use jpegtran to crop the q60, shaving off 8 pixels on each side
* use jpegtran to merge the q60 on top of the q100
* use jpegtran to merge to a stripe

results and details at <http://www.photopla.net/wwp0703/stripes.php>

Greetings from Quebec
Yuv