pngread does not read 12bit gray images

[de Almeida, Valmor F.]

> -----Original Message-----
> From: Søren Hauberg [mailto:soren at hauberg.org]
> Sent: Sunday, July 06, 2008 3:26 AM
> 
> Since you have 'pngread' installed 'imread' will try to use that. So,
> I'd try to use '__magick_read__' directly, i.e.
> 
>   Y = __magick_read__ ("foo.png");
> 
> and see how that works.

Yep. It does work. However it is a little tricky to compare the max(Y(:)) and min(Y(:)) values octave has in memory with the output of imagemagick's "identify" tool.

Just for the record. In the following output from identify

  Format: PNG (Portable Network Graphics)
  Class: DirectClass
  Geometry: 275x220+0+0
  Type: Grayscale
  Endianess: Undefined
  Colorspace: Gray
  Depth: 16-bit
  Channel depth:
    Gray: 12-bit
  Channel statistics:
    Gray:
      Min: 774 (0.188968)
      Max: 1558 (0.380377)
      Mean: 1213.52 (0.296275)
      Standard deviation: 95.3054 (0.0232683)

Octave's values for min and max are: 12384 and 24928. These are obtained from multiplying the corresponding numbers in parentheses from the "identify" output by 65536.


Thanks,

--
Valmor

> 
> Søren