[ptx] Feature Request: Thumbnail cache

[Marko Mäkelä]

On Tue, Mar 02, 2004 at 05:18:02PM +0100, Gergely Kontra wrote:
> While working big panoramas, it will be great, if the hugin project file
> can load quickly. I must edit the same project, and every time I must
> wait, while hugin resizes all the images. How about caching the
> thumbnails?

Or how about embedding thumbnails in the files, or making use of existing
thumbnails?  There are two common variants of JPEG files: JFIF (JPEG File
Interchange Format, implemented by IJG's libjpeg) and EXIF (Exchangeable
Image File, used by digital cameras).  Both image formats allow embedding
of thumbnail images.  As far as I know, thumbnails can also be embedded
in other major bitmap file formats.
  
For what it is worth, I've written a tool, jpegnail, for embedding or removing
thumbnails in JFIF and EXIF images.  The tool is part of a bigger suite,
pHoToMoLo, which I wrote in order to make browseable JPEG image galleries
featuring multiple thumbnail resolutions and static HTML.  The software is
available at http://www.funet.fi/pub/sci/graphics/packages/photomolo/.  You
can see from it how embedded JPEG thumbnails can be extracted from EXIF and
JFIF files.
  
I've been told that the Mac OS X file manager (Finder) makes use of EXIF
thumbnails but not JFIF.  Last when I looked, Nautilus (the file manager
of GNOME) didn't make use of embedded thumbnails, and neither does GIMP 1.x.
  
I don't know why this is so; were the thumbnail embedded in the main image
file, you wouldn't be left with "stray" thumbnail files when you delete the
original.  One of the main argument against embedded thumbnails is that they
consume space.  But I think that a separately stored thumbnail file will often
occupy more disk sectors.  Besides, the default 160×120 EXIF thumbnails occupy
only a couple of kilobytes.
 
	Marko