Image Upload Problem — not reported in forums (?!)

[apconley]

I’m having an unusual problem with image upload into the media library. The site was working fine until several days ago.

Now, when I upload an image it shows significant desaturation–about 25%. In other words, the image is very faint. When the image is loaded into a page, it is very faint and grainy, like the thumbnail shown in the media library. This happens even when I upload images which are already on the site. The difference in appearance is very noticable when ‘before’ and ‘after’ uploads are compared.

To troubleshoot this, I have deactivated all plugins, and changed the theme to unmodified 2013 theme. This makes no difference.

Has anyone else experienced anything like this? I’m not finding this problem reported in forums or via web search.

Thank you in advance for any help you can offer.

[apconley]

Additional info: images are 100 to 200-KB, sRGB or grayscale, .png, sized at 100% of display size, and titles contain no unusual characters (are alphanumeric).

[apconley]

Add. info: I have cleared the browser cache and am running the current version of Google Chrome.