Level/curves changes don't stay after OK

[lhazar]

Something is preventing levels/curves in CS4 from working. Perhaps someone has encountered this problem before?

The Problem: After adjusting either Levels or Curves to the desired point, I click ok, and the image resets itself to its previous state.

Some supporting images:

http://lh6.ggpht.com/_VGkStruEJdI/TABR-fDknLI/AAAAAAAAEHY/lAkNX7BQPOw/Captura%20de%20pantalla%20completa%2029052010%2012 745.jpg
http://lh4.ggpht.com/_VGkStruEJdI/TABR_nDpTiI/AAAAAAAAEHc/aVjmch5SmdE/Captura%20de%20pantalla%20completa%2029052010%2012 835.jpg
http://lh3.ggpht.com/_VGkStruEJdI/TABSArJU4UI/AAAAAAAAEHg/AeqRUyFBdHs/Captura%20de%20pantalla%20completa%2029052010%2012 846.jpg

[JohnMalcolm1970]

I'm not sure exactly what's going on, but one thing I did notice was the asterisk (*) at the top of your document's window: (Layer 0, RGB/8)*

This means that the image is using a colour profile different from your working profile.

Does it only happen with this image? Does it happen with all PNGs? Does it happen with all RGB images? Have you tried converting to greyscale first?

[JohnMalcolm1970]

One other thing I noticed is how weird your levels histogram looks in your first screenshot. Where's all the grey information? I grabbed a screenshot of your file amd hit CTRL+L myself. Looks a good bit different.

http://rookery9.aviary.com.s3.amazonaws.com/4077500/4077891_4d65.jpg

[lhazar]

After a bunch of testing, it seems to be related to the way they were scanned. Not all PNG's react the same way, nor do greyscale or color management help.

They were scanned in a printshop, and the images were saved as pdf's. I later extracted the images and pasted on png.

All images originating from that scan behave the same way, whereas my other images work as intented.

But you gave me a good idea. I'll try taking a screenshot and saving as a new file. It should work...

Thanks for your help. ;D

[JohnMalcolm1970]

After a bunch of testing, it seems to be related to the way they were scanned. Not all PNG's react the same way, nor do greyscale or color management help.

They were scanned in a printshop, and the images were saved as pdf's. I later extracted the images and pasted on png.

All images originating from that scan behave the same way, whereas my other images work as intented.

But you gave me a good idea. I'll try taking a screenshot and saving as a new file. It should work...

Thanks for your help. ;D

Aha... that must be it. If your scanner scanned them as bitmaps (containing only pure black and pure white), and then opened this file in RGB mode, then Levels won't work as it should.

I can now reproduce exactly your problem. It must be do do with the way Photoshop shows you previews of stuff like levels when zoomed out. If you'd posted a screen shot while at 100% I'm guessing it would look a little like this: