Problems reading photo input

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Problems reading photo input

Joe Koski
Now that the image processing routines appear to be working via
ImageMagick-6.2.6, I thought I'd try some tests. I'm using octave-2.1.72
with octave-forge-2006.01.28 on my Mac with OS X 10.3.9.

There seems to be a problem with imread. For example, if I

  octave:1> pix=imread("Full-fire-later-2.tiff");

I get a 3D array of the appropriate size

  octave:2> size(pix)
  ans =

  1032   689     3

but most of the elements of the pix matrix are numerically equal to 255
(except for a few that are zero). This occurs with 2D gray scale images,
color images, .jpg, .ppm, .tiff, etc. The resulting image.m output displays
an appropriately uniform image (black, white, or a single color).

Other than no useful data, I get no error messages or warnings from imread.
The original input images display correctly in PhotoShop, GraphicConverter,
Preview, and even the ImageMagick display routine. If I read data via a
simple 2D gray scale data matrix, image.m gives the correct display.

What am I missing? What do I try next? Any suggestions will be appreciated,
and a small (104 KB) test image file is available on request.

Joe





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Re: Problems reading photo input

Ben salah
I have a question for you. How do you make the relation between octave and ImageMagick in order that imread give a result ? think you
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Re: Problems reading photo input

Stéfan van der Walt
In reply to this post by Joe Koski
On Mon, Mar 13, 2006 at 10:34:54AM -0700, Joe Koski wrote:

> Now that the image processing routines appear to be working via
> ImageMagick-6.2.6, I thought I'd try some tests. I'm using octave-2.1.72
> with octave-forge-2006.01.28 on my Mac with OS X 10.3.9.
>
> There seems to be a problem with imread. For example, if I
>
>   octave:1> pix=imread("Full-fire-later-2.tiff");
>
> I get a 3D array of the appropriate size
>
>   octave:2> size(pix)
>   ans =
>
>   1032   689     3
>
> but most of the elements of the pix matrix are numerically equal to 255
> (except for a few that are zero). This occurs with 2D gray scale images,
> color images, .jpg, .ppm, .tiff, etc. The resulting image.m output displays
> an appropriately uniform image (black, white, or a single color).

I submitted a patch to work around this problem two weeks ago.  I
haven't had time to debug the imagemagick wrapper, though.

See the bug report at

http://sourceforge.net/tracker/index.php?func=detail&aid=1439598&group_id=2888&atid=102888

Further discussions of this problem should probably take place on the
octave forge list ([hidden email]).

Regards
Stéfan



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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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