TYPO3 Core

When I upload an image using the "Images" content type, the image works correctly. If I try to change the settings on Image Quality / Processing, the image doesn't change at all - it'll stay on the format it was uploaded.

The Install tool reports no errors when testing the graphics capabilities, except for the "Write to GIF" test, in which the image appears a bit bigger than the reference.

Typo3 4.1
ImageMagick 4.2.9 (with LZW).
GDLib 2

[GFX][image_processing] = 1
[GFX][thumbnails] = 1
[GFX][thumbnails_png] = 2
[GFX][noIconProc] = 0
[GFX][gif_compress] = 0
[GFX][imagefile_ext] = gif,jpg,jpeg,tif,bmp,pcx,tga,png,pdf,ai
[GFX][gdlib] = 1
[GFX][gdlib_png] = 0
[GFX][gdlib_2] = 1
[GFX][im] = 1
[GFX][im_path] = /usr/local/imagemagick-4.2.9/bin/
[GFX][im_path_lzw] =
[GFX][im_version_5] =
[GFX][im_negate_mask] = 0
[GFX][im_imvMaskState] = 0
[GFX][im_no_effects] = 0
[GFX][im_v5effects] = 0
[GFX][im_mask_temp_ext_gif] = 0
[GFX][im_mask_temp_ext_noloss] = miff
[GFX][im_noScaleUp] = 0
[GFX][im_combine_filename] = combine
[GFX][im_noFramePrepended] = 0
[GFX][jpg_quality] = 60
[GFX][enable_typo3temp_db_tracking] = 0
[GFX][TTFdpi] = 96
[GFX][png_truecolor] = 0

(issue imported from #M8607)