Windows Explorer Thumbnails

[oddball508]

I have used ImageMagick on an number of jpg files to do a number of different combinations of "-flip", "-flog", and "-negate". The images have worked fine but the thumbnail view of the file in WindowsXP explorer shows the old version of the file (ie without the flip, flop of negate).

Any ideas?

Thanks

[el_supremo]

It is extracting and showing the thumbnail image that is embedded within the jpg file.
If you add a -strip argument to your convert command it will remove the thumbnail (and all exif and profiles too) and then XP will show you the actual image because it has to create a thumbnail from the "real thing".

Pete

[oddball508]

Thanks Pete
Is there anyway to control -strip? Or is there anything a little less powerfull? I need to keep the EXIF info.

[anthony]

Use jhead -dt to remove just the thumbnail. It can also extract the thumbnail as a separate image, and autorot the jpeg (and thunbnail) without needing to decode and thus degrade the image data.

IM -strip will degrade the image data as IM goes though the full decode cycle. It is an image editor after all, and is not designed for image format specific operations (eg not reading the image in). if resizing the image or otherwise modifying a -strip can then be done, though Im has no true knowledge of EXIF (only enough for special -auto-orient rotation).

[oddball508]

Thanks Anthony. I was just about the post some information about JHead after finding it. It is an excellent little app. I'm using the -rgt option to regenerate the thumbnail.