I did a comparison between how ImageMagick and GD2 resizes images. The result is here. It also resulted in a patch for imagemagick.inc. Using filter for the -scale parameter is not possible and -resize gives better result. And last but not least the -sharpen parameter greatly improves the quality.

CommentFileSizeAuthor
#1 imagemagick_svn_0.diff649 bytesanders.fajerson
imagemagick_svn.diff651 bytesanders.fajerson

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anders.fajerson’s picture

anders.fajerson commented
StatusFileSize
new imagemagick_svn_0.diff649 bytes

Wrong -sharpen integer.

iraszl’s picture

iraszl commented

This is really great! I'll implement it on creativebits.org soon. It should help our critique section a lot!

anders.fajerson’s picture

anders.fajerson commented

You also increase the quality by providing a -quality option. It defaults to 75 if not set, which usually is a good value (larger value -> larger file size).

More options for the convert command can be fund in the ImageMagick documentation: http://www.imagemagick.org/script/command-line-options.php

If you found any other options that improves the quality or decreseas the file size, please post it here or provide a patch.

peterx’s picture

peterx commented
Category: bug » feature
Status: Needs review » Active

When you convert images to JPEG you are already damaging the images.
(http://petermoulding.com/technology/jpeg_compression)
Using a default JPEG quality setting of 75% is multiplying the damage. Could the quality setting be made a site wide admin setting with one setting for resizing and a separate one for thumbnails? Site administrators could then set 100% for my site and something lower, say 5%, their adult sites.

luperry’s picture

luperry commented

I think simply change "scale" to "resize", and remove the "filter" argument would be sufficient. as the sharpen option often makes the thumbnail/preview bigger than the original picture in filesize. sometimes it may even make the image look worse than before(especially if the original picture is pixelated).

also, supplying the "filter" argument seems unnecessary for "scale":

–scale geometry

scale the image.

See –resize for details about the geometry specification. –scale uses a simpler, faster algorithm, and it ignores the –filter selection if the –filter option is present. Offsets, if present in the geometry string, are ignored, and the –gravity option has no effect.

mhutch’s picture

mhutch commented
Status: Active » Needs review

+1 for this -- I couldn't stand the atrocious images that GD2 and the default imagemagick settings produce. I was about to move over to flickr, when I found this.

It works very nicely, and I especially like the sharpening -- it adds a beautiful crisp edge which helps one to see detail in the smaller picture sizes.

I also use -quality 80, because imagemagick will detect the compression level from the picture and use that unless you explicitly set a level, and many of my pictures' originals have very high quality.

dado’s picture

dado commented

+1 this has great thumbnail quality AND fixed imagemagick for me. prior to this patch i could not get imagemagick to work (and GD is not istalled on my server)

drewish’s picture

drewish commented
Status: Needs review » Closed (won't fix)

someone's created a wonky image magic module to do this.

Jean-Philippe Fleury’s picture

Jean-Philippe Fleury commented

drewish wrote:
> someone's created a wonky image magic module to do this.

Hi,

In concrete terms, how can I specify my parameters for jpg resizing without having to touch the code of the module Image, since each update of this module would override my patch.

Thanks.

Cablestein’s picture

Cablestein commented

Has this been integrated officially?

I see on the module page it's mentioned:
"ImageMagick Advanced: Adds advanced ImageMagick options such as image sharpening to the ImageMagick image toolkit. This component is unsupported."

But I can't seem to find the advanced ImageMagick options.

As well when I open this .inc file and look at the patch vs the current code, the lines seem diff a bit.

Cablestein’s picture

Cablestein commented

Looks like PHP's native GD2 library IS able to do some 'sharpen' functionality... it's just not very apparent.

There's a GD2 command called imageconvolution. With it you can put a sharpen effect on an image, for example using this persons' script. Here's another posting on it, where they also have some tool to play with parameters... you can see an example image here. The scripts look pretty basic to me, I'm pretty sure this could be easily placed into GD's settings in Drupal admin.

I've used imagemagik recently, and it's great, but the IT guy at work is having trouble compiling it for a particular server. He just wonders why we can't use GD since it comes built-in with PHP. I have an account on a shared host too, they only have GD2, I'd rather not have to go through the hassle of requesting imagemagik.

MakeOnlineShop’s picture

MakeOnlineShop commented

Hello,

I wanted to improve IMAGECACHE quality (for Ubercart shop):
http://groups.drupal.org/node/12521

I tried Imagemagick but I can't see any difference between GD2 and ImageMagick so maybe I did something wrong ?

Do you think that GD2 is actually enough ?

Thanks.