import not capturing overlays.

[ianw]

I don't know if this is an enhancement request or a bug report, so I'm doing an enhancement request for now!

Autodesk suggested to reduce some stability problems we had in Maya that we turn on support in X for Color Index Overlay planes (in the NVIDIA driver, this is activated with the option CIOverlay in the xorg.conf). Unfortunately it looks like import does not support capturing overlays, as any overlay section of a window is drawn with all-black pixels, while non-overlay sections are captured correctly. (x11vnc has the same problem unless the -8to24 option is used) Gnome's built-in screenshot application captures these correctly, but it doesn't support capturing regions of the screen like import does, only windows. Gimp also works, but it's cumbersome to bring up a full editing app when all you want is to save a quick snapshot of a region of the screen. Even olde 'xv' captures these regions correctly, with help from some patches on its site. Is there any plan to add overlay capture support to Imagemagick?

[magick]

Try

• import -screen myscreen.png

[ianw]

Unfortunately, same result. import -screen captures the entire screen (we just want to capture the portion we draw with import's cursor), and it's also capturing without the overlays.

[magick]

Did you try -frame?

[ianw]

Unfortunately, the same result: an image that looks like a screen capture of where I selected except for the overlay sections, which are captured as black pixels. I also tried options like, say, -depth, though I suspect that's related more to the post-capture images as they're writte.

[anthony]

The overlay sections may not be on the actual display frame buffer. which is why IM failes to capture them. they may be specially handled by your computers video chip, whcih would need specialized code to extract.

For example few screen captures I've seen captures cursours, whcih im most cases is a good thing. You also can rarely capture direct video windows.

An exception to this I have seen is capturing the output of a virtual machine that is running the application. The virtual simplified the video handling and sanatizes the display to a form that can be captured. I have used this technique to grab images from some 3D games.