Last modified: 2010-08-31 18:14:15 UTC
Nearly all photographs benefit from minor sharpening when reduced to thumbnail size. It would be nice if MediaWiki automatically applied some sharpening to all JPEG thumbnails. The ability is already there in GD and ImageMagick. Ideally there would be a way to disable it (I'd suggest |rawthumb| rather than |thumb| for thumbnails with scaling only) but given how thumbnails are used this doesn't seem strictly necessary.
If the image should be sharpened in any particular resolution, the uploader should do that manually. An automatic action on all images will produce shitty results in a few cases, without editors having a chance of finding out why. I feel inclined to WONTFIX this right away.
In other words, you prefer to optimize for the uncommon case, rather than the common case.
interesting, can anyone provide with a gallery of examples? :)
*** Bug 7383 has been marked as a duplicate of this bug. ***
(in replay to comment #1) >If the image should be sharpened in any particular resolution, the uploader >should do that manually. An automatic action on all images will produce shitty >results in a few cases The full size uploaded image has to be as sharp as possible. But please believe me, if you scale down an image you has to resharpen it for a better look. (In reply to comment #3) > interesting, can anyone provide with a gallery of examples? :) Please see example at bug 7383. If possible by the used libs, please add a little bit sharpness to the generated thumbs. The actual generated thumbs are to blurry even though the original full size uploaded image is really sharp.
Copying that example here: Compare http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Champions_League_trophy.jpg/375px-Champions_League_trophy.jpg with http://static.flickr.com/95/224894467_8f0e771cce.jpg So Flickr are obviously use sharpening to good effect.
I would really appreciate automatic sharpening for thumbnails PLUS more quality for thumbnails. The quality of the thumbnails generated by mediawiki are o.k. for "old CRTs on bad VGA- cabling", and for lowres uploads. but the higher the resolution of the uploaded images, the worse the thumbs/scalings become. As you ask for examples, to visualize the need for this function a) Sharpeining for Thumbs Please compare -Raw Image "sharp, "uploaded in hires" http://upload.wikimedia.org/wikipedia/de/d/d6/K%C3%B6nigsallee_in_D%C3%BCsseldorf_Girardetbr% C3%BCcke_bei_Nacht.jpg -Raw Image "sharpened" "low resolution upload" http://upload.wikimedia.org/wikipedia/commons/1/1a/Koenigsallee_okt2004.jpg In the article the thumb of the lowres-picture looks brilliant, but the thumb of the hires is really ugly. http://upload.wikimedia.org/wikipedia/de/thumb/d/d6/K%C3%B6nigsallee_in_D%C3% BCsseldorf_Girardetbr%C3%BCcke_bei_Nacht.jpg/300px-K%C3%B6nigsallee_in_D%C3% BCsseldorf_Girardetbr%C3%BCcke_bei_Nacht.jpg and compare to http://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Koenigsallee_okt2004.jpg/300px- Koenigsallee_okt2004.jpg Or on drawings: Fulres: http://upload.wikimedia.org/wikipedia/commons/c/ce/Schwarzplan_Tausendfuessler.jpg thumb: http://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Schwarzplan_Tausendfuessler.jpg/200px- Schwarzplan_Tausendfuessler.jpg b) More q (quality) for thumgs there are often very disturbing artefacts on the thumbnails have a look at the Tomatoe-Images original: http://upload.wikimedia.org/wikipedia/commons/d/d2/Tomatoes_plain_and_sliced.jpg thumb: http://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Tomatoes_plain_and_sliced.jpg/250px- Tomatoes_plain_and_sliced.jpg -jha-
I would really appreciate automatic sharpening for thumbnails PLUS more quality for thumbnails. The quality of the thumbnails generated by mediawiki are o.k. for "old CRTs on bad VGA-cabling", and for lowres uploads. but the higher the resolution of the uploaded images, the worse the thumbs/scalings become. As you ask for examples, to visualize the need for this function a) Sharpeining for Thumbs Please compare -Raw Image "sharp, "uploaded in hires" http://upload.wikimedia.org/wikipedia/de/d/d6/K%C3%B6nigsallee_in_D%C3%BCsseldorf_Girardetbr%C3% BCcke_bei_Nacht.jpg -Raw Image "sharpened" "low resolution upload" http://upload.wikimedia.org/wikipedia/commons/1/1a/Koenigsallee_okt2004.jpg In the article the thumb of the lowres-picture looks brilliant, but the thumb of the hires is really ugly. http://upload.wikimedia.org/wikipedia/de/thumb/d/d6/K%C3%B6nigsallee_in_D%C3% BCsseldorf_Girardetbr%C3%BCcke_bei_Nacht.jpg/300px-K%C3%B6nigsallee_in_D%C3% BCsseldorf_Girardetbr%C3%BCcke_bei_Nacht.jpg and compare to http://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Koenigsallee_okt2004.jpg/300px- Koenigsallee_okt2004.jpg Or on drawings: Fulres: http://upload.wikimedia.org/wikipedia/commons/c/ce/Schwarzplan_Tausendfuessler.jpg thumb: http://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Schwarzplan_Tausendfuessler.jpg/200px- Schwarzplan_Tausendfuessler.jpg b) More q (quality) for thumgs there are often very disturbing artefacts on the thumbnails have a look at the Tomatoe-Images original: http://upload.wikimedia.org/wikipedia/commons/d/d2/Tomatoes_plain_and_sliced.jpg thumb: http://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Tomatoes_plain_and_sliced.jpg/250px- Tomatoes_plain_and_sliced.jpg -jha-
(In reply to comment #3) > interesting, can anyone provide with a gallery of examples? :) I've made an example here: http://de.wikipedia.org/wiki/Benutzer:Smial/thumbtest Comments are welcome smial
(In reply to comment #9) > (In reply to comment #3) > > interesting, can anyone provide with a gallery of examples? :) Please visit http://www.smial.prima.de/bilderwerkstatt/thumbtest/wikimedia_thumbtest.html Six examples for different values for the "convert" command. Comments or questions welcome here: http://de.wikipedia.org/wiki/Benutzer_Diskussion:Smial/thumbtest In short: convert "input file" -thumbnail %sizex -sharpen 0x0.8 "output file" should be a useful compromise for either small thumbs down to 120px or previews at least up to 800x600px. smial
Fixed with r21411 by Tim Starling. Thanks a lot!
See also Bug 24857 (sharpening affected by ImageMagick update).
