Re: [boost] Half-baked GIL IO extension review

Subject: Re: [boost] Half-baked GIL IO extension review
From: Christian Henning (chhenning_at_[hidden])
Date: 2010-12-07 10:55:38

Hi Edd,

> All I know is that libpng and libjpeg provide access to this information in
> a crude form. I don't know whether physical dimensions are mandated by the
> respective formats or if the libraries are implementing common extensions,
> but in each case, the information is there.
>
> In the case of libjpeg, the information is exposed/advertised in the
> jpeg_decompress_struct and jpeg_compress_struct structures. You can see how
> I use them here:
> http://bitbucket.org/edd/jpegxx/src/ea2492a1a4a6/src/read.cpp#cl-62
> http://bitbucket.org/edd/jpegxx/src/ea2492a1a4a6/src/write.cpp#cl-75
>
> In libpng, have a look in the docs for e.g. png_get_x_pixels_per_meter.
>
> I'm entirely ignorant in the case of libtiff, I'm afraid.

Cool. I'll add this to my todo list. Seems trivial to add. Do you have
by any chance some images containing such information?

Christian