Images Darken Slightly When Flattened

[randall rb8272116]

I use PS Cloud and produce large (1-5 Gb) image files with 3-12 layers using PhotoShop's Large Document Format (psb). When I flatten a multilayered psb file, image tones of the flattened psb file look identical to the unflattened psb file. If I save the flattened psb file in psb format, it still looks identical to the unflattened psb file. If I save the flattened file in TIFF format, however, the TIFF image often looks slightly darker than the unflattened and flattened psb images when viewed using PS, Bridge, or other applications. Darkening is not great but is definitely enough to change the mood of images. I have plenty of computer resources so I don't think that is a problem. I was advised to enter   Edit>Preferences>Performance>CacheLevels and reduce the number of CacheLevels. I reset CacheLevels to 2 (I cannot reduce it to 1) but saving a flattened psb file in TIFF format still produces a darker image. I need TIFF files for printing, posting on the web, etc, so darkening is a problem. Has anyone experienced this darkening problem? 

[c.pfaffenbichler]

Please set the Status Bar to »Document Profile« and post screenshots taken at View > 100% with the pertinent Panels (Layers, Channels, Options Bar, …) visible of the tif and layered psb? 

Did you embed the profile when saving? 

»or other applications«

That is irrelevant if you don’t state whether they are color managed or not. 

[randall rb8272116]

I found other discussions of this darkening problem and have learned that darkening does not result from flattening multilayered files but rather is related to viewing the files. I verified this by comparing my unflattened and flattened images in PS at 100% and areas that appeared darker in Bridge and other applications look identical when viewed at 100%. Of course, viewing files at 100% isn't useful when the files are very large; you might see part of a tree but you certainly can't see the forest so to speak. So, the problem with large files is viewing and different applications (e.g. Bridge) show different file sizes and different amounts of darkening. Is it necessary to prepare different versions of an image for different applications if the original image file is very large? For example, do we need an original edited version, another version edited for web display to eliminate darkening and yet another version edited for printing? 

P.S. My display monitor and printer are both well profiled 

[davescm]

At zoom levels less than 66.7%, the on screen preview is composited from 8 bit, interpolated layers. This is done for speed. At 100% view, the full image data visible in the screen area is used and at the full bit depth. For many images the difference is minimal but on some it is noticable.   Always check at 100% zoom.

Dave

[randall rb8272116]

Thank you for your input, I learned a lot from your comments on this topic. As usual, things are more difficult when huge files are used! 

[c.pfaffenbichler]

The issue davescm explained usually becomes evident only under certain circumstances with photographic images. Primarily, in my experience, if they are extremely noisy. 

But as you seem unwilling to comply with (repeated) requests it might be a waste of time trying to help you. 

[c.pfaffenbichler]

Again: Please set the Status Bar to »Document Profile« and post screenshots taken at View > 100% with the pertinent Panels (Layers, Channels, Options Bar, …) visible of the tif and layered psb. 

[c.pfaffenbichler]

Coincidentally I filed a Report on the impossibility of setting Cache Levels to 1 in Photoshop 2020 a couple of weeks ago. 

https://feedback.photoshop.com/photoshop_family/topics/photoshop-2020-setting-cache-levels-to-1

I was loathe to call it a bug but as the documentation still lists the option it probably is a legitimate one.