Hello all, Our company has used ImageMagick for many years to successfully generate thumbnails. Since Feb 4th of this year we have used ImageMagick-6.4.9-2-Q16-windows-dll.exe and that has worked fine.
On Tuesday I upgraded to ImageMagick-6.5.6-10-Q16-windows-dll.exe and am now getting complaints (from multiple customers) that our thumbnails are fuzzy. Our actual thumbnail build process is complex & uses PerlMagick but I can demonstrate the issue using these simple commands: convert -size 420x420 -thumbnail 420x420 -quality 75 -colorspace RGB -sharpen 0.1x0.2 source.jpg th420_%im_version%.jpg convert -size 140x140 -thumbnail 140x140 -quality 75 -colorspace RGB -sharpen 0.1x0.2 th420_%im_version%.jpg th140_%im_version%.jpg The first creates a 420px thumbnail from the source, and the second creates a 140px thumbnail from the 420px one. Using ImageMagick 6.4.9-2-Q16 we get this: http://87.252.62.61/thumb/th140_64.jpg With ImageMagick 6.5.6-10-Q16 we get this: (fuzzier, specifically with the girl's freckles washed out) http://87.252.62.61/thumb/th140_65.jpg I have copied our build script and linked to the original source image and shown both thumbs side-by-side at http://87.252.62.61/thumb/side_by_side.html Is anyone able to help with this? I have searched the changes documentation between 6.4.9 and 6.5.6 and I do not see anything related to changes to thumbnailing or sharpening. I haven't seen anything on this list or in the forum related to it. Could it be something like I need to uppercase "-Sharpen" now or something??? I could revert to 6.4.9-2 but I hate to go back. Also I could find new sharpen arguments for 6.5.6, but the ones we had took weeks to decide upon and will affect millions of images from thousands of different photographers/cameras and so the best option would be to make what worked before work again. Thanks for any help! Also this list gave me some help back in June re: color searching and I was asked to post back what worked and what didn't. I used the Histogram function to get a list of which colours existed inside the image. I used our 140px thumbnail and used only the center 80% of it so as to reduce the amount of data to churn. Then I mapped all the colours into the 216-colour web colours (by dividing each r,g,b on 0-255 by 6 to get 0..5 and then taking $int_colour = 36 * red + 6 * green + blue). Then using the frequency of those 216 colours within each image, I created a database table of mappings and built the search here: http://theimagefile.co.uk/?Action=_SE&padv=1 . Originally I had used 4096 colours with some proximity-matching but the database table grew too big. So now it uses only 216 colours and requires an exact match. I was also concerned about JPG colour reduction where the colours of individual pixels were different from what is seen by the naked eye -- however somehow this hasn't been an issue, maybe because we use the smallest 140px thumbnail as a data source or because we simplify to 216 colours. I had experimented with various operators to smooth out the image colours but they didn't seem to help, so I ended up just using the raw thumbnail. _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
