Got black image when printing figure with trasparencies

Dear all, I created a plot with a partially transparent rectangle (to emphasize a range of values). When I try to export it (to EPS, PNG, JPEG, TIFF,... both with "print" and GUI) I get an image almost completly black. See attached example of the exported file (a.png) and a snapshot of the window (Screenshot-Figure1.png). I am attaching the .fig file too. If I do not add the rectangle, everything is OK.

I am currently using version 7.5.0.338 (R2007b) on Linux 2.6.35-32 (Ubuntu), Java 1.6.0_26.

Answer 1

[Riccardo]

I am answering my own question since I found a "turn around" that could be useful to someone else with the same problem.

I obtained the same effect by creating a 3D non-transparent patch with a z-value < 0, e.g.,

patch([x0 x0 x1 x1], [y0 y1 y1 y0], -1+[0 0 0 0])

In this way the patch is "behind" the lines and the same effect is achieved without using transparencies.