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  2. RPG400-L
  3. April 2005

Re: Extracting Exif data and thumbnails from image files



David Gibbs wrote:

Rob Dixon wrote:


Information about exif can be found at http://www.exif.org.


Many thanks - I had forgotten this - will investigate.



Google is your friend :)

Sometimes I neglect my friends - pressure of work etc.!!

Thumbnails can't be 'extracted', as far as I know ...


I thought that I had read that they are stored in the header of the
image file but I cannot remember where!



I'm no expert, but I don't think so ... there always is a delay when I
pull up a thumbnail view in Windoze on folder while it builds the
thumbnails.


Of course I could be wrong.


On reflection, I think that you are right.

you have to create
your own smaller sized version of the image. I'm not sure you could do
it easily in RPG, although I suspect there are a number of C libraries
you could investigate porting that should be easy enough to call or bind.


I think that it would be too slow do create them repeatedly on the fly. I already have ceated my own in IrfanView in batch on my PC and stored
them in the IFS, but wondered if this was unnecessary step.



First time, yes ... but if you stored the thumbnails in a cache, or
along side the original, it would only be a one time hit.

The sequence in which thumbnails and originals are displayed in ERROS will vary all the time as this is determined by the user request or query. ERROS allows any one image file's URL to be indexed 'n' ways although the URL is only stored once in ERROS. Few users have access to the folders in the IFS and images are most unlikely to be displayed in the sequence in which they are in a folder. I think that a cache, unless absolutely enormous, would not help.

I will have to stick to my present method which does work very well. I just always like to extract every little extra bit of performance that I can.

Many thanks for your help

Rob


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