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03/03/2011 05:14:25 PM · #1 |
I don't shoot JPG very often; I always shoot RAW. But for the recent minimal editing street photography challenge, I have a few JPG's that I'd like to make proper edits to. I'm using dear old Paint Shop Pro X2. My question is this: After I open the file and make my changes, how should I save the file to avoid further lossy compression? I can save it as a TIFF, or just save the changes directly to the JPG file (I'm working on a copy, of course). I think it will apply JPG comression again if I save the JPG. But I'm not quite sure what happens if I save it as a TIFF.
If it matters, my changes for most of these will consist of a color balance and curves adjustment, and cloning out some bad pixels.
Thanks.
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03/03/2011 05:22:44 PM · #2 |
If you are going to be doing your editing in several stints, saving and closing the file several times, then yes, use a TIFF as your working file, and save to JPEG at the end for submission. If you are only opening the file to edit once, completing all your edits at one go (heck, how much editing can there be in Minimal??) then there's no real benefit, you're only re-compressing once, which you'll have to do anyway to submit. |
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03/03/2011 05:36:22 PM · #3 |
Thanks kirbic. These aren't being edited for any challenge. I wonder now, should I open the file, save it as a TIFF, and make my edits (and subsequent edits if I so desire) to that? Or should I make the edits to the original JPG? Or does it matter?
And what about rotating? I know that rotating a JPG file is a lossy operation. Would you save it off as a TIFF, rotate it, and then create a new JPG from it?
Sorry for the questions. Trying to understand how this works. |
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03/03/2011 06:30:18 PM · #4 |
Sounds like you are better off creating a TIFF to do your work on, then saving as JPEG as the last step. Yes, rotating a JPEG can incur some penalty, albeit a small one. Remember that you can open a JPEG and edit as much as you care to, it's only upon resaving that the re-compression happens.
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03/03/2011 06:32:51 PM · #5 |
I save my in work files as a .pspimage file, the PaintShop Pro native format.
It's a lossless format and preserves any layers and masks you might have. I flatten and save my final file as a JPG. I'm not terribly concerned about the pspimage being incompatible with other editors, since I only use it for things that are in an in-work state. If you do want wider compatibility, you could also save as a Photoshop .PSD file, which PSP X2 can both read and write.
I save my final product as a full resolution JPG with the lowest possible compression ratio of 1, and then resize it to produce other sizes as needed. Even if I reopen this low compression JPEG, any loss to compression at this point is pretty much not going to be visible. I might try an experiment and run a JPEG through multiple open and saves at minimal compression, in order to see how many cycles it takes to produce visible degradation.
Message edited by author 2011-03-03 18:33:13.
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03/03/2011 09:16:52 PM · #6 |
Interesting about your workflow, Steve. I always save TIFF's. So now that I have these in-camera JPG's from the street photography shoot -- well, that threw me for a loop. I guess my question boils down to, what happens with when you open a JPG and save it as a TIFF? Since TIFF is lossless, it must take each pixel of the JPG and save it unaltered. That's what kirbic confirmed for me in my roundabout way of asking.
I've used the PSP native format, but it's massive! I only use it when I have a project in progress (i.e. layers and such) and have to step away from it.
Thank you both. |
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03/03/2011 09:24:56 PM · #7 |
Originally posted by bvy:
I've used the PSP native format, but it's massive! I only use it when I have a project in progress (i.e. layers and such) and have to step away from it.
Thank you both. |
tiffs can be too...
Message edited by author 2011-03-03 21:25:13. |
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03/03/2011 09:47:46 PM · #8 |
Originally posted by bvy: Since TIFF is lossless, it must take each pixel of the JPG and save it unaltered. |
Exactly. If you open the JPG and save it as TIF, it's still the same thing. No loss to compression, but you can't add any image quality that's not already there.
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03/03/2011 11:36:13 PM · #9 |
Originally posted by bvy: I've used the PSP native format, but it's massive! I only use it when I have a project in progress (i.e. layers and such) and have to step away from it. |
I don't know about PSP, but the Photoshop native format uses lossless compression when the file is saved to disk, so that it's not quite as big as might be expected, especially if it only contains Adjustment Layers or layers containing only a few pixels (not a copy of the entire picture), such as might be used for retouching a small area.
The TIFF format can be saved to disk using the LZW option, which will use lossless compression (essentially the same as ZIP) to reduce file size.
AFAIK, the later CS versions of Photoshop use lossless compression for the maximum-quality JPEG setting, so it should actually be OK to open and re-save JPEGS as long as you use that setting.
Lastly, a few image editors (such as the free IrfanView) can perform some simple "lossless JPEG operations" such as 90°-incremental rotations, which supposedly will not compromise image quality. |
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03/04/2011 07:16:30 AM · #10 |
Thanks General. First off, PSP is no Photoshop! I don't do much with the PSP format (Steve could speak to it better) but I've had it bring my PC to a near grinding halt before.
The problem I've had with the LZW option (again in PSP) is that it wouldn't preserve EXIF after being saved. The uncompressed option did. I wonder if it's the same in Photoshop... |
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