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64 bit TIFF files load incorrectly


tomp
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note: thread started when I thought I was dealing with TGAs but in fact I should have said "TIF". Sorry.

Paint.Net has some undesirable behavior when loading TGAs with four 16-bit channels. The left side is the "original" image and the right is the image after Paint.Net has saved it back out.

Unfortunately I can't source these images myself but if it is not possible for the PDN shepherds to easily create these images I'll try to work something out.

The attachment is zoomed way in; the vertical stripes are one pixel wide. This is a screen capture from my image differencing utility; the right side image is what I see in PDN as well as what I get in my own TGA loader. Note too that PDN truncates it to 8 bits per pixel, the image size is retained, but (unfortunately the screencap doesn't show this) the content itself is stretched in width by maybe 30% and height remains the same and unstretched. A wild guess is that it's reading RGBA data but stuffing it into RGB?

I downloaded the latest update today. Win Vista x64 with a lot of RAM and CPU.

For my needs, I don't require the preservation of 16 bits per channel; I would be fine with truncation to 8, but I don't endeavor to speak for everyone. Just to be clear, I am not looking for a discussion on the merits (or lack thereof) of 16 bits per channel; that decision is out of my hands and I have image data in that format that I need to deal with.

Thanks!

post-81461-129851916136_thumb.png

Edited by tomp
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I think you're the first to try it at all... if you give me a copy of the 16-bit TGA, I can see if it's simple enough to add support in the next update.

The Paint.NET Blog: https://blog.getpaint.net/

Donations are always appreciated! https://www.getpaint.net/donate.html

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Ugh, when putting together my request for the legal clearance folks here I noticed that the files are TIFFs, not TGAs. Sorry for the misrepresentation. Since the zipped image is 744k I can't attach it here, but can you email me and I'll bounce the zip back to you? If you speak 7-zip, that's about half the size of the .zip file. Uncompressed it's a shade over 2M.

Edited by tomp
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Honestly, you shouldn't ever use TIFF if you can avoid it. It is provided in Paint.NET only as a best-faith convenience feature.

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Ahh ok, TIFF not TGA.

There's likely nothing that can be done about that. Are you on XP, Vista, or Win7? The reason I ask is that in Win7, the GDI+ component actually uses WIC for loading files, and so the behavior may be different (whether it's for better or for worse, I don't know).

The Paint.NET Blog: https://blog.getpaint.net/

Donations are always appreciated! https://www.getpaint.net/donate.html

forumSig_bmwE60.jpg

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Ego:

Just to be clear, I am not looking for a discussion on the merits (or lack thereof) of 16 bits per channel; that decision is out of my hands and I have image data in that format that I need to deal with.

I should have assumed that I should have added that discussion about the merits of a file format are similarly out of my hands. The fact is that only TIF meets the requirements that we have.

Ahh ok, TIFF not TGA.

There's likely nothing that can be done about that. Are you on XP, Vista, or Win7? The reason I ask is that in Win7, the GDI+ component actually uses WIC for loading files, and so the behavior may be different (whether it's for better or for worse, I don't know).

I downloaded the latest update today. Win Vista x64 with a lot of RAM and CPU.

For history's sake, 3.5.7 was released in the past couple of days, and that is the version that I'm using.

I'm not expecting a fix, certainly. If it's too much trouble then it's not a huge worry to me, although it is a slight bummer. Gimp doesn't handle these files either, although Windows Photo Gallery displays them properly although editing seems to be a bit more challenging in that app. Maybe they work on Win7? One day I'll get an upgrade...

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