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All Forums > Tech Talk > Tech Talk Forum Page 17 > Any imaging experts out there?
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 19 2011 : 11:22PM
I have a bunch of digital images taken with an old digital camera that I need to edit. The original images were in Jpeg format. Since there are a lot of photos (Each photo needs individual attention) and it's going to be a big project, I wanted to do the editing in several steps. At least four.
1. Crop
2. Remove red eye
3. Remove skin blemishes
4. Color correction
So I obviously didn't want to resave the pictures as Jpegs each time. I wanted to use a lossless format so I converted all the pics to TIFF using Irfanview's batch conversion (Saving the original Jpegs).
My question is this. This is the first time I've used lossless compression for pictures so I know nothing about it. I'm guessing this is the best way to do what I want to do with as little generation loss as possible? I know the file sizes are considerably larger but I don't really care about that. Am I missing anything obvious?
Edited by - randomprecision on Apr 19 2011

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Jacco All-Star Supporter
All-Star Member

"liable to deprave and corrupt"
2673 Posts
5/04
Posted - Apr 20 2011 : 4:51AM
Lossless is the way to go for an iteration like this. But make sure you have actually converted your pictures to a real lossless TIFF. TIFF's can use compression too and I am not familiar with Irfanview and its settings. And test it all on a few images first of course.
Jacco
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 20 2011 : 6:29AM
Thank you Jacco. Yes. I am using LZW compression. I'm assuming that I'm OK as long as I save the pic to a TIFF with LZW compression each time, correct?
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Jacco All-Star Supporter
All-Star Member

"liable to deprave and corrupt"
2673 Posts
5/04
Posted - Apr 20 2011 : 4:50PM
Yep, that should work. I hope you will be able to do a lot of the work as batches or it will take a serious amount of time.
Jacco
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 21 2011 : 5:16PM
^ Thanks. Unfortunately, the pics all need individual attention. The batch conversion was probably the only batch work I'll be doing on them.
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picman
Senior Member

Nothing says I love you so much as a tongue in the ass.
2884 Posts
1/03
Posted - Apr 24 2011 : 8:44PM
If space isn't an issue, you shouldn't even use the LZW compression. TIFFs may compress a little based on uniformity of color of neighboring pixels, but that's as much as you should want done. When they're opened in an image editor, they'll all be the same size. Even the JPGs.
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 25 2011 : 1:21AM
So you're saying I should save them as uncompressed TIFF files or what?
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picman
Senior Member

Nothing says I love you so much as a tongue in the ass.
2884 Posts
1/03
Posted - Apr 25 2011 : 6:48AM
Yes. The size difference shouldn't be profound, and the files aren't likely to be very big to begin with. LZW compression doesn't make sense any more in a world where hard drive space runs in the terabytes.
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 25 2011 : 10:52PM
OK. So what about this...
The original batch conversion to TIFF files with LZW compression is already done (a week ago). And I've already gone through about half of the images and cropped them and saved to LZW. Would it make sense for me to start all over just to get that little extra bit of quality?
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picman
Senior Member

Nothing says I love you so much as a tongue in the ass.
2884 Posts
1/03
Posted - Apr 26 2011 : 9:30PM
No, just take off the LZW whenever you re-save them, assuming you'll be doing more with them. It's not a big deal breaker, but anytime you re-save with compression, it degrades the image a little more.
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - Apr 27 2011 : 3:27AM
OK. Thanks.
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DrP0rn0
Senior Member

1836 Posts
5/04
Posted - May 22 2011 : 11:28PM
I don't know what picman is going on about. LZW is a patented, lossless compression algorithm. It's built in to the spec of TIFF to save space WITHOUT affecting quality. The only possible motivation for NOT using LWZ, would be to have a faster loading time on each file. There is NO loss of quality, just like a RAR or a ZIP file does not change what is in the file. LZW, like Zip or Rar is LOSLESS. Nothing is lost.
Image manipulation is detailed and weird enough without worry about non-existant losses.
Dr. P
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RandomPrecision
Senior Member

Enjoy!
8175 Posts
3/06
Posted - May 27 2011 : 5:59PM
OK. Thanks. Every little bit of info helps. It's appreciated.
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