JPG-XR

[simon]

Hello Pierre
Great job. this new version fixes a number of issues.

About JPG-XR, however, it seems that no parameter is taken into account in beta 1: whatever the value of quality, internal color format and block filtering, the output is ever lossless (i.e. as if with quality 100, no chroma subsampling), as checked by comparing the .JXR with an initial .BMP image.

By the way, it seems to me that chroma subsampling in JPEG and JPEG-XR are similar, at least in principle. Currently the labels are YUV444, YUV422 and YUV420 in JPEG-XR, and (1x1,1x1,1x1), (2x1,1x1,1x1) and (2x2,1x1,1x1) in JPEG. IMHO, It should be preferable to use the same labels for consistency.

cheers
simon

[masterjp-germany]

Dear Pierre,

the new beta version 2 does not use the settings of the jpeg-xr option dialog.
Please correct it! Thank you.

Best regards,

masterjp

[xnview]

I can't reproduce, if you change quality no change?

[Drahken]

The JXR quality slider gets ignored. You can set it anywhere from 1 to 100 and it'll always come out the same. The color setting & the block setting are the only things that actually register.


A possibly related issue is that when you click the options button on the save dialog, it doesn't take you to the JXR options, just a blank section (as if there were no settings available for JXR). I thought that there weren't any settings for it until I decided to look at the list of formats in the write options dialog. If I click the JXR one manually it takes me to the settings correctly.
I don't know if this issue is related to the quality slider getting ignored or not.

[xnview]

yes right... will be fixed in beta3

[xnview]

Please try 1.98 beta3

[masterjp]

Good job! The jpeg-xr settings work.

What do you think about an extra jpeg-xr tab within the menue file => export dialog?
That would be very nice. This dialog should have two kinds of compressions:

Quality: 1-100 %

Compress to filesize (KB):

[Drahken]

The settings work now (in beta 3), but the bug of not going straight to the jpxr settings when you click the options button on the save dialog still exists.
File->save as->jpeg xr->options->[blank page]->jpeg xr settings.

[xnview]

right

[simon]

Hello

There remains a number of problems with JPEG-XR writing

1) Setting YUV 444 and 100% correctly provide a lossless compressed image. However, keeping 100% but setting YUV to 420 leads to a lossy and slightly heavier image than YUV444 (whereas it should be quite lighter), and setting YUV to 422 leads to a much heavier image than YUV444 ((whereas it should be sligtly lighter). In other terms, using chroma subsampling strangely leads to both lossy and heavier images.

2) the compression cursor is taken into account now, but in a strange way: using 95% indeed makes it possible to get a nice, lighter image, but using 50% provides a very light but very poor quality image (lighter and worse than a 5% JPG).

cheers
simon

PS. Please note that I performed these tests with "overlapped block filtering" set to "off", as I have no idea of the meaning of this parameter.

[xnview]

I've tested again with original source code, and it's the same...