XnView jpeg2000 quality surprises
Posted: Thu Jun 05, 2008 10:20 am
I have done some tests on Adobe PS2 with the fnord jp2 plugin to compare the quality of the jp2 files it generated with the quality from Xnview's jpeg2000 jp2s.
I converted the same TIFF (generated with Raw Therapee) in these programs and generated jpeg2000 files at different quality settings but having the same size between the programs.
In the first photograph I found that at lower until middle quality settings (200kb, 400kb, 600kb for my files), PS's plugin preserved much better detail than Xnview's jpeg2000 module, the latter moreover created blotches and blurred objects as if there was some strong noise reduction.
At higher quality settings (800kb and 1200kb) Xnview's aforementioned blotches get smaller and it looks like XnView actually amplifies the fine grain of the TIFF to coarse noise. However Xnview's jpeg2000 had the lead in contour detail and the file looked almost the same as the original TIFF in these terms at high quality settings, while the detail in the PS file did not get that much better with increasing file size.
You do not have to look closely to see this, these are no minor problems for people concerned about image quality, and that includes all serious photographers.
From the second picture comparison, I get to the same conclusion about the texture/grain problem of XnView's files, however the detail of the PS files is not so good as XV's files, interestingly: jagged lines and unsharp contours.
So I looked at a third photograph, randomly chosen to know what the hell is going on why is the sharpness now better with XV? This was a sharp photograph compared to the first picture.
And that was yet another susprise. The lowest quality file (200kb) from Xnview showed exceptional fine detail retention (the insect's body) whereas PS's file lagged far behind in high detail areas. However, XnView's file failed to reproduce the out-of-focus background faithfully, which was blurred with blotches again like in the first image. PS's file however did a good job in this. This was still visible to a lesser degree in the 500kb file.
So in a nutshell, the texture problem of XV's files was visible in all photographs. At small sizes, we had blotching (dramatic loss of fine detail and blurred backgrounds) at bigger sizes it became coarse grain, bigger still it was amplified finer grain (like luminance noise), in high quality files. However the sharpness and texture of XV's files for sharp, contrastful, changing areas was great even in small files.
I uploaded the crops of the files I used for comparison here:
http://dl.free.fr/aLbBarHul/1stpicture.zip
http://dl.free.fr/arFTbJrOs/2ndpicture.zip
http://dl.free.fr/aHesYRAHd/3rdpicture.zip
http://dl.free.fr/a3VhcK3X1/4thpicture.zip
the link will not be valid anymore 30 days after download from there stops, sorry.
The lossless files (not supplied) and the TIFF served as controls and were identical.
Note: the PS files did not have the same color exactly as if XnView could not read their AdobeRGB (ans sRGB for the last picture) color profile (PS did read its own appended color profile information), although I usually did not have this problem. Nevertheless I could read the files although I usually could not read PS jpeg2000 files again with XnView.
http://newsgroup.xnview.com/viewtopic.p ... highlight=
Weird...
Further, I found that sometimes when choosing a selection area from the drop down menu after a right-clic on the image, I could not undo or crop the selection. Choosing the size of the selection from the menu bar was no problem.
Configuration: Nikon D40 adobe NEFs converted by Raw Therapee v2.4ml
Core 2 Duo processor, 1 Go RAM Windows Vista
PS 6 with Fnord jp2 plugin, Xnview latest version
I converted the same TIFF (generated with Raw Therapee) in these programs and generated jpeg2000 files at different quality settings but having the same size between the programs.
In the first photograph I found that at lower until middle quality settings (200kb, 400kb, 600kb for my files), PS's plugin preserved much better detail than Xnview's jpeg2000 module, the latter moreover created blotches and blurred objects as if there was some strong noise reduction.
At higher quality settings (800kb and 1200kb) Xnview's aforementioned blotches get smaller and it looks like XnView actually amplifies the fine grain of the TIFF to coarse noise. However Xnview's jpeg2000 had the lead in contour detail and the file looked almost the same as the original TIFF in these terms at high quality settings, while the detail in the PS file did not get that much better with increasing file size.
You do not have to look closely to see this, these are no minor problems for people concerned about image quality, and that includes all serious photographers.
From the second picture comparison, I get to the same conclusion about the texture/grain problem of XnView's files, however the detail of the PS files is not so good as XV's files, interestingly: jagged lines and unsharp contours.
So I looked at a third photograph, randomly chosen to know what the hell is going on why is the sharpness now better with XV? This was a sharp photograph compared to the first picture.
And that was yet another susprise. The lowest quality file (200kb) from Xnview showed exceptional fine detail retention (the insect's body) whereas PS's file lagged far behind in high detail areas. However, XnView's file failed to reproduce the out-of-focus background faithfully, which was blurred with blotches again like in the first image. PS's file however did a good job in this. This was still visible to a lesser degree in the 500kb file.
So in a nutshell, the texture problem of XV's files was visible in all photographs. At small sizes, we had blotching (dramatic loss of fine detail and blurred backgrounds) at bigger sizes it became coarse grain, bigger still it was amplified finer grain (like luminance noise), in high quality files. However the sharpness and texture of XV's files for sharp, contrastful, changing areas was great even in small files.
I uploaded the crops of the files I used for comparison here:
http://dl.free.fr/aLbBarHul/1stpicture.zip
http://dl.free.fr/arFTbJrOs/2ndpicture.zip
http://dl.free.fr/aHesYRAHd/3rdpicture.zip
http://dl.free.fr/a3VhcK3X1/4thpicture.zip
the link will not be valid anymore 30 days after download from there stops, sorry.
The lossless files (not supplied) and the TIFF served as controls and were identical.
Note: the PS files did not have the same color exactly as if XnView could not read their AdobeRGB (ans sRGB for the last picture) color profile (PS did read its own appended color profile information), although I usually did not have this problem. Nevertheless I could read the files although I usually could not read PS jpeg2000 files again with XnView.
http://newsgroup.xnview.com/viewtopic.p ... highlight=
Weird...
Further, I found that sometimes when choosing a selection area from the drop down menu after a right-clic on the image, I could not undo or crop the selection. Choosing the size of the selection from the menu bar was no problem.
Configuration: Nikon D40 adobe NEFs converted by Raw Therapee v2.4ml
Core 2 Duo processor, 1 Go RAM Windows Vista
PS 6 with Fnord jp2 plugin, Xnview latest version