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Re: new octave-forge release


From: Paul Kienzle
Subject: Re: new octave-forge release
Date: Mon, 20 Mar 2006 01:20:51 -0500


On Mar 20, 2006, at 12:15 AM, Joe Koski wrote:

on 3/19/06 8:32 PM, Paul Kienzle at address@hidden wrote:


On Mar 17, 2006, at 1:45 PM, Joe Koski wrote:

... For color images, bmpwrite (for Mac display
without X11) has problems:

ready to call bmpwrite
error: flipud: Only works with 2-d arrays
error: evaluating if command near line 48, column 3
error: called from `flipud' in file
`/usr/local/share/octave/2.1.72/m/general/flipud.m'

This is not unexpected because a color .jpg is read as a 3-D matrix. I
looked at bmpwrite, and it appears flipud and transpose need to be
replaced
with their 3-D equivalent (or break the image into three 2-D matrices
for
processing). I'd try but I don't know the desired .bmp color output
format.
I can test changes to bmpwrite, if somebody suggests them.

I put a new bmpwrite which handles m x n x 3 images with RGB values in
the range 0-255.  Call it using bmpwrite(im,'file') rather than
bmpwrite(im,colormap,'file').  I updated extra/MacOSX/image.m to use
this new format.

Instead of displaying images in preview, we should be using gnuplot 4.1
plot with image function (http://www.gnuplot.info/links.html)

Since this may require an upgrade of gnuplot I will leave it to the
mac/windows/linux packagers to sort out which version of image to use.

- Paul

Paul,

Sorry, but I'm missing something. Is the new version of bmpwrite.m already in the recent distribution, but I'm misusing it, or is the new version that
you refer to now in octave-forge CVS?

New this evening.

In subsequent image experiments, my tests indicated that saveimage.m and
imwrite.m also lack the 3d matrix capability. Am I correct?

No idea.

Incidentally, I found that on my Mac, I can start X11, just leave it open,
and then run octave in a standard Terminal.app window. The ImageMagick
display routine will then open the image via X11, when the "standard"
image.m routine is used. Maybe we should suggest this approach for image
processing stuff, and leave AquaTerm for routine 2d plots. I'll do more
testing to see if I can both 2d plot with AquaTerm and display an image at the same time. (The bmpwrite.m approach is probably preferable, because you
don't need to remember to start X11 when you might need it.)

I would go with the bmpwrite for now, at least until there are binary
builds of gnuplot 4.1 available for Mac OS X.

I'm willing to give gnuplot-4.1 a try, and have gotten the CVS development version from the gnuplot site. Has anyone any experience with gnuplot-4.1? Is it ready for day-to-day usage? Per Persson says that with some exports (or some such) you could have both gnuplot-4.0 and gnuplot-4.1 installed,
and easily switch between them. I'll try to research that too.

I did some fiddling of the image_gp routines from the gnuplot page so that
they use the new __gnuplot_... style commands, but I wasn't able to test
them because I don't have gnuplot 4.1.  See attached.

- Paul

Attachment: imagegp-0602.tar.gz
Description: GNU Zip compressed data


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