XnView Software

I have a Grayscale image on my computer that when viewed as a thumbnail using Window Explorer and Irfanview displays it as i expected, Grayscale . When looking at this particular files thumbnail in XnViews browser window though, the thumbnail is in color. However, when i then open this file in XnView , it shows it in Grayscale.

Does this mean that, for this jpeg file, there are actually two images packed into the file. the thumbnail and then the image file. If so, is there a way to extract the color thumbnail from this file?

Yes, jpegs can have thumbnails attached.

If you want to transfer thumbnail to seperate file, that would require a different tool. Like jhead.

To turn off display of attached miniatures:
Options... Thumbnail>Appearance>[ ]Use embedded thumbnail

To erase miniature from file without resaving:
Browser menu... Edit>Metadata>Clean... [x]Exif thumbnail

And cache may need rebuilt to see changes.

Good answer, marsh. Reason for the wrong display in XnView is the mismatch of the embedded EXIF thumbnail and the image.

There is one more possibility:
You can recreate/update/synchronize the EXIF thumbnail, in browser mode select the file and select "Edit > Metadata > Recreate EXIF thumbnail".