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Date: 08/08/20 11:32
Image Posting Problems
Author: cn6218

I've been experiencing some image quality problems lately here, and on other platforms like Flickr.  Some images, lose quality (primarily contrast) when viewed in a browser after posting, compared to what I viewed on the same screen when I was editing the picture.  Here's an example: https://www.trainorders.com/discussion/read.php?15,5080997,5081057#msg-5081057

It seems to happen only with scans of slides, particularly ones which are files larger than 500KB (I realize images here are supposed to be under that size, but Flickr has no such limit, and it still happens there).  There seems to be something about these scans (more grain perhaps?) that increases the file size significantly.  Interestingly, if I download the image from the Trainorders site, and compare it side to side with image I uploaded, they look identical, and both are the same size, about 770KB in the case of the example above, which seems to suggest that the Trainorders site doesn't really re-compress the images after all.

The scanner in question is a Plustek 7500i with Silverfast software, processing is done with an old copy of Photoshop Elements II (yeah, it's probably time to upgrade!).  I have no such problems posting pictures that are natively digital, although I'm using the same copy of Photoshop for them, and more or less the same procedures (contrast manipulation and sharpening).  I would describbe what I'm seeing as clipping of the white levels to perhaps 70 or 80% of what they should be.  Other examples are here: https://www.flickr.com/photos/109788224@N05/50132541168/in/dateposted-public/

Thanks in advance for your thoughts.


Date: 08/08/20 12:36
Re: Image Posting Problems
Author: trainjunkie

I don't use Elements but how are you saving the final files? Is the scanner profile somehow being saved (embedded) with the file? Do you have an option to save it with no profile? In my version of Photoshop, when I "Save for Web", I have the option to "Embed Color Profile", which I always uncheck. Sounds like your scanner profile is embedded in the final file. you might look into how that occurs in Elements and see if you can turn that option off.

Date: 08/08/20 13:30
Re: Image Posting Problems
Author: cn6218

Elements does have a Save for Web option, which I haven't really used up to this point, but it does make a difference.

There is no option to embed a profile, and I just left the Quality setting at 71, which is where it came up.  In this particular case the file is only about 289 KB, so I could probbably bump that up higher, but there doesn't seem to be a need.

The scanner does have a color gamut setting for web or print.  Setting it to "web" didn't seem to make a difference.

The new version of the image has been added to the first link above, and at least for this picture, it does seem to cure the problem.  Thanks for the help!


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