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Re: imread (repost)
From: |
Daniel J Sebald |
Subject: |
Re: imread (repost) |
Date: |
Tue, 05 Aug 2008 12:43:15 -0500 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20041020 |
Bill Denney wrote:
Currently (and also in matlab I believe) you can only view one image
at a time. So my question is basically, what is behind image? Say I
run the following
im = rand (100, 100, 4);
im (:, :, 4) = 1; # full transparancy
figure
imshow (im)
What should I expect to see?
I would expect to see the axis background color. If the axis background
color is set to none, then I would expect to see the figure background
color. I believe that if you set the figure background color to none in
matlab, you see a cross-hatched pattern. When exporting, I would
anticipate that the graphics backend would take alpha into account
relative to the output device, so if the output was to ps or pdf, it
would convert the background color to the color as visible on the screen.
I'm not saying that this is easy, just that-- to me-- the above is the
right way to do it.
In my opinion, the right way is for PostScript to handle alpha blending. Wish
it would. It's the easiest place to implement such a feature, i.e., at the
last step just blend the contents together.
I guess my feeling, whether it is gnuplot handling the alpha channel or a new
intermediate graphics backend, is to not support alpha blending if the output
medium doesn't support it. So if one wanted to do alpha blending, they'd have
to output to some driver that supports it and then convert that result (likely
a bit map) to, say, PostScript. Not an elegant solution, but I don't think it
is worth putting large amounts of effort into a feature that gets limited use.
Dan
imread (repost), Daniel J Sebald, 2008/08/05
- Re: imread (repost), soren, 2008/08/05
- Re: imread (repost), Daniel J Sebald, 2008/08/05
- Re: imread (repost), soren, 2008/08/05
- Re: imread (repost), Bill Denney, 2008/08/05
- Re: imread (repost), soren, 2008/08/05
- Re: imread (repost),
Daniel J Sebald <=
- Re: imread (repost), Shai Ayal, 2008/08/05
- Re: imread (repost), Daniel J Sebald, 2008/08/05
- Re: imread (repost), Thomas Weber, 2008/08/06
- Re: imread (repost), Daniel J Sebald, 2008/08/06
Re: imread (repost), Daniel J Sebald, 2008/08/05
Re: imread (repost), Przemek Klosowski, 2008/08/05