This is to confirm that the thumbnail option "Gray, somewhat faster . . ." is off, and turning it on and then off has no effect.
The zbThumbnail.info file is explained below, per Canon's technical support. I deleted the file and still had the same problem, so I do not think this file's existence explains my problem. I think you correctly identified the issue, when you initially responded to Lamberew's initial post, starting this thread. My testing and workaround, are described below.
First, the background of my situation:
The problem folder in question (call it the root JPG folder, for the sake of identification) has JPG's as well as subfolders containing JPG's. My Dopus Preferences for Lister Display Modes/Thumbnails Mode does not have "generate JPEG thumbnails in gray-scale (slightly faster)" checked. However the preferences "Display thumbnails for folders" AND "Generate folder thumbnails from images inside folder" are checked, as is "Load all thumbnails in a folder automatically."
If I have "High quality image scaling (may be slower)" checked when the the JPG's are "added to this folder", the thumbnails appear in black and white. If I then, in Dopus's preferences, uncheck the "High quality image scaling (may be slower)" box, the B&W thumbnails promptly turn to color. If I then "check" the "High quality image scaling (may be slower)" box, the thumbnails STAY in color, rather than revert to B&W.
I think you correctly identified the issue, when you initially responded to lamberew's initial post, starting this thread. As you said in your response, when I double click on a B&W thumbnail, the image appears in color.
At this point, I don't think it's necessary to send a file as it appears that I'm dealing with the same issue as Lamberew encountered, which you have processed. It would appear that the simple "workaround", for now, is just to make sure the checkbox for "High Quality image scaling" is not checked in Dopus's Preferences/Thumbnails Mode.
Thank you for your thoughts on this issue. Nella
*Canon's ZoomBrowser EX software creates the zbThumbnail.info files. The ZBThumnail.info has information pertaining to the various thumbnail images that represent the images that are contained in your Pictures folder. Nothing will happen if the thumbnail file is deleted. A new one will be created the next time ZoomBrowser EX is launched. It is not necessary to move the thumbnail file when moving images. ZoomBrowser EX will update the thumbnail files as needed.
ZoomBrowser Image Index File
Category Raster Image Files
File Description Stores information about images saved in a Zoom Browser photo album; includes thumbnail image data, which enables quick browsing of images in the album; created when one or more image files are opened by ZoomBrowser.
The ZoomBrowser index file is typically named "Zbthumbnail.info" and is saved in the same directory as the images it corresponds to; the Zbthumbnail.info file is usually hidden, but may appear inside your album folder depending on your computer's file viewing settings.
Program(s) that open info files: Canon ZoomBrowser EX