Export alpha channel as animation?

[danjb]

Xara3D generates an alpha channel, since it can save one to a PNG file as a still image. I know I can't save a video/animation with an attached alpha channel (not sure what file format would do that), but is there any way to save JUST the alpha channel of an animation? That's the approach taken by another animation program called Particle Illusion.

When you export an AVI file, you can choose to export either the animation itself, or a gray-scale version of the animation's alpha channel. You can then easily recombine these in things like Adobe After Effects for nice looking results. Is there any chance of doing this in Xara3D? Since it's already generating the alpha channel, maybe it's as simple as a checkbox that says whether the alpha channel or the main animation is saved when the AVI file is exported?

[Egg Bramhill]

Hi danjb and welcome,

I'm not 100% with you here. Xara3D can export to a transparent animated gif.
Why would you want to export the reverse?

[danjb]

Thanks for your response! Unfortunately, GIF transparency doesn't work well for smooth edges and shadows because it's binary. Read the section titled Binary Transparency: the Scourge of GIF in the link to see why GIF can't be used for professional looking compositing.

One of PNG's advantages over GIF is real alpha channel transparency. While Xara 3D outputs nice alpha transparency to PNG's, it doesn't do animated PNG's. Clearly it calculates alpha transparency, but I haven't found any way to get it out in an animated or video format.

[Intbel]

Thanks for your response! Unfortunately, GIF transparency doesn't work well for smooth edges and shadows because it's binary. Read the section titled Binary Transparency: the Scourge of GIF in the link to see why GIF can't be used for professional looking compositing.

One of PNG's advantages over GIF is real alpha channel transparency. While Xara 3D outputs nice alpha transparency to PNG's, it doesn't do animated PNG's. Clearly it calculates alpha transparency, but I haven't found any way to get it out in an animated or video format.

Xara Xtreme exports animated gifs.
It will also export each separate frame, with a single mouse click, in transp. png with alpha channel.

I hope that is useful info.

[danjb]

Xara Xtreme exports animated gifs.
It will also export each separate frame, with a single mouse click, in transp. png with alpha channel.

Do you know how I can export a series of frames in an animation?? If I click the Export... button, it always seems to export the current image.

[remi]

There is a great tip from Charles Moir (CEO of Xara Ltd.), how you're able to export all Animation frames in only one step.

The option "Export each layer to a file of its own" is availabe for PNG and GIF images.

Regards,
Remi

[danjb]

The option "Export each layer to a file of its own" is availabe for PNG and GIF images.

Thanks for that tip, that would definately help! Do you know if I need Xara Xtreme for that function, though? When I press CTRL+SHIFT+E in Xara 3D and choose PNG as the export file type, I get this dialog:

http://www.butterfields.net/xara/xaradialog.jpg

There is no option here like the one you mention?

[remi]

Yes, you need Xara Xtreme (it's a option of the export dialog from Xara Xtreme).