Re: imread (repost)

[Shai Ayal]

On Tue, Aug 5, 2008 at 8:43 PM, Daniel J Sebald <address@hidden> wrote:

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.

Does postscript support blending?

Shai