Rotating images / scans

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kartracer

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If I rotate a digital image, and / or a scan (slide or negative), is the quality compromised?
 
Hi. I think you need to open it in PS, then save as a .psd before you rotate or crop. That will preserve as much detail as possible. Editing a .jpg and saving as a .jpg loses data. I imagine the loss of quality is negligible, but you might as well save as much as possible.
 
Thanks. I should have rotated them all correctly at scan time - now I've got to do the work to upright many of the scans. I guess I was thinking about square vs. rectangular pixels (astro and video cameras...) where a rotation would alter the image.
 
I would avoid rotating using something that decompresses and then recompresses. You don't know what it does to the data. Anyone who states that you have to resave jpegs many times to see any degradation doesn't fully understand what is going on when uncompressing and resaving ;)

You can rotate images by just changing the EXIF information in the file, thus not actually changing the image at all. Try something like the freeware lossless rotator: http://annystudio.com/software/jpeglosslessrotator/ (never tried it, but it's free and manipulates the correct data).
 
That's worth a try. But, for the most part, I scanned as TIFF. I would be naturally cautious with JPEG, but does TIFF present any issues when rotating?
 
Shouldn't have any issues with TIFF...
 
Danny_Two said:
No, not at all. You would have to re save a jpeg many time to see any degradation.
Click to expand...

I disagree with that completely

There is a function called "JPEG Rotate" which is lossless. Use that if it's a JPEG. If it's not a lossy file format like JPEG then just open & rotate

List of applications that do lossless rotation here

Nick Froome
 
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