Here is a patch to add sharpening functions to ImageAPI. Both GD and Imagemagick are covered although GD just falls back to a simple convolution matrix as noted throughout. I will open an Imagecache issue for the patch that includes the sharpening action.

CommentFileSizeAuthor
#4 imageapi-sharpening-v2.patch6.55 KBMoonshine
imageapi-sharpening-v1.patch2.73 KBMoonshine

Comments

dopry’s picture

dopry commented
Status: Needs review » Needs work

Moonshine, you're actually implementing an 'unsharp mask' with imagemagick and it can be done in php for GD.... see http://vikjavev.no/computing/ump.php...

the only thing missing from the reference implementation that imagemagick has is sigma... The sigma is used in the building of the gaussian matrix... see: http://en.wikipedia.org/wiki/Gaussian_blur

I would like both toolkits to be as functionally identical as possible. I don't know how to compute the gaussian matrix and don't have time to grok it at the moment, but I would accept and updates patch with sigma fixed for imagemagick until it can be properly implemented in GD as well.

Moonshine’s picture

Moonshine commented

Yep, it's an unsharp mask. Although I think it's still best for the action to refer to itself as a "Sharpen(ing)" action as unsharp still confuses many...

After quickly glacing at that link, it also looks like there will have to be alternate GD code for php < 5.1, as it doesn't have imageconvolve(). :/ Either way, I'll take a peek in the next few days and try to merge that technique in there.

dopry’s picture

dopry commented

php 5.1 is the very minimal version of php supported by image API.. I actually only officially support php 5.2.

Moonshine’s picture

Moonshine commented
StatusFileSize
new imageapi-sharpening-v2.patch6.55 KB

Updated patch using unsharp mask technique for gd (- sigma).

Moonshine’s picture

Moonshine commented
Status: Needs work » Needs review
drewish’s picture

drewish commented

marked #266298: Unsharp masking... as a duplicate.

dopry’s picture

dopry commented
Status: Needs review » Fixed

committed to DRUPAL-5 and HEAD... untested.. I'm coming for you if it doesn't work moonshine :)

tnx...

Anonymous’s picture

Anonymous (not verified) commented
Status: Fixed » Closed (fixed)

Automatically closed -- issue fixed for two weeks with no activity.