[OctDev] octave imaging

[Stefan v. d. W. <st...@su...>]

Hi All

I would like to know what image/matrix format is preferred by Octave.

All the imaging functions seem to be written for images in
[0, 1].  This could be rather confusing, for example:

octave:128> I = imread('lena256.jpg'); % read image
octave:129> colormap(gray(256));       % set colormap to 256 gray scales
octave:130> imshow(I)                  % display lena
octave:131> histeq(I)                  % oops! expected I in [0,1]
error: `n' undefined near line 30 column 16

So imshow does not handle images in [0,1] (it handles only indexed
   images), but the other functions expect images in [0,1]:

octave:140> [p,m] = gray2ind(I/255, 256)

works correctly, while

octave:140> [p,m] = gray2ind(I, 256)

doesn't.

It is, for example, very counterintuitive that the following code
doesn't work:

imshow(imread('image.jpg'))

MATLAB handles the different images with 'classes', but I do not think
Octave has that functionality.

Thanks in advance.

Regards
Stéfan van der Walt