[IPOL discuss] input image format in demos

[Nicolas Limare]

Hi Pascal,

> I have a question about input image format in IPOL demos' python code. It 
> seems you can select the format by setting the string app.input_ext (for 
> example '.ppm' in graph cuts demo) but that first the images are saved in PNG 
> format, and then additional files with required format (here PPM) are 
> generated. Is this assumption correct?

Yes. In the file lib/base_app.py, lines 152 and following:

    def process_input(self):
        # [...]
        for i in range(self.input_nb):
            # [...]
            # open the file as an image
            try:
                im = image(self.work_dir + 'input_%i' % i)
            except IOError:
                raise cherrypy.HTTPError(400, # Bad Request
                                         "Bad input file")
            # save the original file as png
            im.save(self.work_dir + 'input_%i.orig.png' % i)
            # convert to the expected input format
            im.convert(self.input_dtype)
            # check max size
            if self.input_max_pixels \
                    and prod(im.size) > (self.input_max_pixels):
                im.resize(self.input_max_pixels)
                # [...]
            # save a working copy
            im.save(self.work_dir + 'input_%i' % i + self.input_ext)
            # save a web viewable copy
            im.save(self.work_dir + 'input_%i.png' % i)
            # delete the original
            os.unlink(self.work_dir + 'input_%i' % i)

The uploaded files, already received and saved as `input_X` in the
folder `self.work_dir`, are read as an image (via the PIL library),
and if successfully read, are
* saved in PNG, original size, as `input_X.orig.png`
* converted (in memory) to the requested data type (color, gray, ...)
* downsized if necessary
* saved in the requested format (app.input_ext) for further processing
  by the program
* saved in PNG for inclusion in the web pages

-- 
Nicolas LIMARE
http://nicolas.limare.net/                         pgp:0xFA423F4F
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