Windows Shell Hack to Show Thumbnails for THMs

Started Aug 1, 2003 | Discussions thread
adam c Contributing Member • Posts: 899
Mike - link now dead...any chance of another?

This info deserves to be bumbed on a semi-regular basis. I'm willing to try the registry hack, but would prefer to just download your "easy option" - any chance of making it accessable again?



Mike Fried wrote:

Tonight I got the precious free time that I've been looking for to
resume working on my Canon CRW decoder utilities (I can already
decode files including most metadata). However, tonight, I decided
to work on making it so that CRW files could have thumbnails in the
Windows shell. While I was at trying to figure out how to register
my Shell Extension, I came across an article which gave me an
instant idea. The THM files are JPEGs (rename a .thm to a .jpg and
you get a preview thanks to IE). Why can't I just use the image
extractor used by JPEGs? Why not indeed? It turns out that the IE
thumbnail extractor will read THM files, and correctly parse the
JPG image out of it.

Yes, it is a registry hack. Basically, we tell the Windows
Explorer/Shell to use the TridentImageExtractor class
({7376D660-C583-11D0-A3A5-00C04FD706EC}) to handle the
ImageExtractor interface ({BB2E617C-0920-11D1-9A0B-00C04FC2D6C1})
on the .thm extension.

This registry hack won't rotate the files for you... I guess that
IE doesn't understand whatever rotation information Canon embeds
into the file. I'm still working on my CRW Image Extractor, which
when it is done will be able to rotate the THM files (fast), or
failing them existing, extract the JPG from the CRW file (slower),
or failing that, process the CRW image data (really slow). I'll
pass it around when I finish it. I'm also thinking about some of
the other shell extension functions as described in

Remember, you tweak your own registry at your own risk. I'm not
responsible if you mess things up. This is supposed to work with
Windows 98 and above, but I only tried it on Windows XP.

Anyway, here's the contents of the .REG file:
Windows Registry Editor Version 5.00



--End of THMPreview.reg--

If launching notepad and typing all that in (all of the things in
the []s should be on the same line) is scary, I'll make it easy for
you. Just download

To give fair credit where credit is due, the article which inspired
me to try this in this way was:

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