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Anarion

JPG chrom subsampling options

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I've been using Paint.net for ages and it is a wonderful tool for simple and quick image editing. However, there's this one thing that bugs me: no way to disable chroma subsampling. Sometimes it's okay to use chroma subsampling to save space but sometimes the results are horrible, this is one example that shows the issue:

nochroma4wsz3.png
Size before uploading: 1,41 KB, png (lossless RGB)

nochromagus8o.jpg
Size before uploading: 61,0 KB - progressive jpg, 100% quality, no chroma subsampling, XnView

chroma5yssm.jpg
Size before uploading: 42,9 KB - 100% quality, 4:2:0 chroma subsampling, Paint.NET

What happens in noisy image:
nochromasvs3w.png
Png.

 

chromax2smi.jpg
Jpg.

Quite horrible. Sure, in this case PNG is superior format in every possible way but imagine if that was part of a larger image. It would still look like that even though the rest would look okay (although I never use jpg chroma subsampling myself - it just hurts the colours and image quality too much).

I'd really appreciate option to switch between most common subsampling modes like in PSP for example:
image10bsgl.png
Though three most common modes would be just fine i.e. 4:4:4 (no subsampling), 4:2:2 and 4:2:0. Also progressive jpg support would be nice too since it's usually smaller.

That's something I'd really like to see in the future version - also I'm really looking forward to 4.0!

Edited by Anarion

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Would optimized .png images help in your situation, or are you required to use .jpg?

I didn't know there was optipng plugin available, that's handy (I use command line version for batch converting my game screenshots for example). But sadly it doesn't solve the issue. Above examples just highlighted the issue.

 

Sometimes jpg is better option especial when posting normal images or game screenshots (though in later case png can be good option too, depends about the image). Assuming I'd had some image that doesn't compress well as png (i.e. "noisy" image, lots of detail) but then I'd have small red text on blueish background it would look quite bad when using the built in jpg encoder in paint.net. Of course I can use another tool to do it but it kinda beats the purpose of the built in jpg save option because the quality is what it is. It would save time if one could save directly to jpg without chroma subsampling, now I have to use another app for that.

 

There are some special cases where I'd really need that option to get the best image quality/size trade off when posting lossless images wouldn't be practical (or if the file size is issue).

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I've actually laid the groundwork for this in 4.0 by implementing a WIC wrapper (GDI+ doesn't let you configure this). It'll have to wait for a post-4.0 release, however. I do have a bug filed for this functionality.

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On 9/1/2013 at 11:56 AM, Rick Brewster said:

I've actually laid the groundwork for this in 4.0 by implementing a WIC wrapper (GDI+ doesn't let you configure this). It'll have to wait for a post-4.0 release, however. I do have a bug filed for this functionality.

 

Hi Rick, curious if there has been any progress made on this in the recent Paint.NET builds? I've come across a 4:4:4 image that is beautiful, when edited and "saved" by Paint.NET it drops the quality down to 4:2:0 with no option to preserve the bits. It's a crazy complex image and the downgrade is quite noticeable. I've tried the OptiPNG-file-type-plugin but found that through several trials with different settings, the quality is preserved (awesome!) but the file size is not reduced relative to a standard PNG file.

 

Original File: 4:4:4 ~ 5mb

Save as JPG (100%): 4:2:0 ~ 3.5mb

Edit, Save as PNG ~ 11mb

Save with OptiPNG ~ 11mb

 

... so, curious about the 4:4:4 option and when this might be made available? If nothing else, I'm a little concerned now in learning that Paint.NET doesn't AT LEAST preserve the original JPG settings when re-saving ... even when selecting the 100% setting in the save-as dialogue.

 

Thoughts?

 

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No specific timeline, there hasn't been progress on this. The WIC wrapper I mentioned is incomplete, and it'll be a bunch of work to finish it, but I've been accumulating various things that will benefit from or depend on it. Maybe this year? It's in the "4.1.x" bucket right now (that is, probably before v4.2 whenever that is).

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4.1.7 will support choosing 4:4:4, 4:2:2, or 4:2:0 subsampling. The default will be 4:2:2. Before, 4:2:0 was always used because that's what GDI+ did without giving any options for it.

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