Thumbnails API question

[David Moore]

I suggest that the API just give the application a list of which
thumbnails are available in the file along with their exact dimensions,
and then the application will pick which one it wants and then request
it.  That seems like the most general approach.

Regards,

David

On Sat, 2006-09-16 at 23:56 -0400, Will Stokes wrote:
> Interesting question. From a developers stand point say I wanted a
> 200x100 pixel thumbnail. I'd like to ask libopenraw to give me a
> preview image ideally no less than 200x100 pixels in size. libopen raw
> would then figure out the best preview image to give me. if non is
> 200x100 it would give me the biggest one. if some are bigger it would
> give me the smallest preview image that is at least 200x100 pixels in
> size. libopenraw would not auto scale the image for me, that's my job,
> as I might excel as faster or more accurate scaling depending on my
> situation, or I might even want to wait to do scaling until I'm ready
> to throw an image on teh screen, say if I'm eventually just loading it
> as an OpenGL texture and mapping it to a quad.
> 
> Anyways, that's my two cents....
> 
> This is getting exciting. My first use of RAW will not be to allow the
> user to edit/view full size RAW images but to throw thumbnails up in
> my little EXIF/IPTC editor (Reveal). Currently I have some forked
> forked dcraw code but if I could just use libopenraw to handle loading
> thumbnails so much te better!
> 
> -Will
> 
> On 9/16/06, Hubert Figuiere <hub at figuiere.net> wrote:
> > Hi,
> >
> > I have an API question. It is not about the use but its design as I have to
> > make choices, and I'd rather make the right one.
> >
> > Extracting the thumbnails is done today by asking for a size. There are
> > currently 3 sizes:
> >                 OR_THUMB_SIZE_SMALL,
> >                 OR_THUMB_SIZE_LARGE,
> >                 OR_THUMB_SIZE_PREVIEW
> >
> > SMALL is the smallest, basically 160x120 that Exif has. But not all files have
> > it, like DNG.
> > LARGE is the larger one, vary from vendor to vendor, and may not be available.
> > Typically 640x480, but not necessarily.
> > PREVIEW is typically the JPEG version of the raw file as some format like PEF
> > seems to have, or CRW. The problem how to define such preview?
> >
> > I plan to provide an API to query these types, and an API to convert them to
> > the format you want, ie PNG or JPG, and list all what is available.
> >
> > But the question is:
> > should I just change the API to extract the thumbnail giving a base dimension
> > (like 320) and let libopenraw decide which one is the best (like the smallest
> > thumbnail that does not require oversampling to achieve the size)?
> >
> >
> > Hub
> > _______________________________________________
> > Libopenraw-dev mailing list
> > Libopenraw-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/libopenraw-dev
> >
> 
>