IrfanView Thumbnails and embedded JPG thumbnails

[quietdragon]

When I point IrfanView Thumbnails at a remote directory, loads the files into the viewer very slowly.

Does IrfanView Thumbnails use the EXIF thumbnail embedded in the JPG file, or does it reconstitute the thumbnail ?

For example, Windows Explorer uses the following algorithm:

http://blogs.msdn.com/b/oldnewthing/archive/2011/05/17/10165117.aspx

When Explorer wants to display a thumbnail for an image, it first checks whether the image comes with a precalculated thumbnail. If so, and the thumbnail is at least as large as the thumbnail Explorer wants to show, then Explorer will use the image-provided thumbnail instead of creating its own from scratch. If the thumbnail embeded in the image is wrong, then when Explorer displays the image-provided thumbnail, the result will be incorrect. Explorer has no idea that the image is lying to it.

Does IrfanView Thumbnails use a similar algorithm ?

[Bhikkhu Pesala]

No. IrfanView creates its own thumbnails. In thumbnail options you can change the size and disable image resampling to speed up generation of thumbs, or stop the process at any time, but I guess its always going to be slow on remote drives.

Thumbnails are not cached either. There are several existing feature requests to cache thumbs.

[quietdragon]

No. IrfanView creates its own thumbnails.

Ah ... I see. My JPEG files all have good quality embedded thumbnails already. It's a shame that IrfranView cannot exploit these to display summary content rapidly.