Alpha Chanel

[Ufuk Zayim]

Hi,

My question is I've imported a movie with alpha chanel.Want to fillout just the image not whole background.But I can not find out.Could you please help me.

Thank you

[Synthetik]

Let's say you have the mosaic you generated above and want to get rid of the parts that aren't in the source masked areas.  You can always set the selection to the source alpha,then invert the selection (so that the background and not the object is now selected), and then turn on masking and erase to white or whatever solid background color you want.

 

Prior to SA V5.5, the selection buffer was hijacked by the path start regionization code in the paint synthesizer.  The election buffer was set to the current region being filled as the individual regions were filled in.  You could use this to your advantage in the paint synthesizer, since any selection modulation would be based off of the individual region selection masks as the path start regionization rendered all of the individual regions.

However, the issue with this 'feature' is that it blew away the global selection masking.

In V5.5.5 you can turn this behavior on or off.

To do that, you use the Region Mask Opt in the Path Start control panel.  This parameter option is only going to show up in the Editor if you are using a Path Type where it is applicable.

'Use Global' option means that the global selection is not changed. So if you have it set to this option, then you could use selection masking as you ran the regionize effect to mask it.  So you could set the selection to the source alpha, then turn on masking, then run the path start regionization paint preset.  So this is another way to do it.  Or you can do it after the fact as i first described.

 

I'm assuming people know how to use the canvas : selection menus to do what i just described.  I can explain that in more detail if people are confused or don't know.

 

[Ufuk Zayim]

Sorry but I am cofused.Because I just began to learn SA. Could you please put some screen shots?

Thank you.

 

[Synthetik]

So i took one of the factory mosaic paint presets and loaded an image folder brush into it.

I also grabbed a source image that has an embedded alpha channel in it.

So if i just run the mosaic paint preset on the source image i get the following.

The entire canvas is filed in with paint.

Now suppose i want to use the source image alpha channel as the selection mask.  I can set the selection to the source alpha by running the canvas menu command below.

If i erase the canvas to white and then turn on masking *Mask checkbox in the main operation toolbar is turned on) then i see the selection as an overlay on the canvas.

If i press Action to run the mosaic paint effect, the painting will be masked by the current selection (which we set to the source alpha).

Note that i have the Region Mask Opt parameter in the Path Shape control panel set to 'Use Global'.  As i said in my first post in this thread, if i had it set to 'Each Region as Mask', then i would not have been able to mask the painting to the global selection.  Just something to be aware of when using  path start regionization paint effects like this one.

 

I could invert the selection based on the source alpha channel, turn on masking, and then erase to white if i wanted to take the first screenshot canvas that painted the entire canvas and erase all of the parts of the canvas that correspond to the source alpha being turned off to some default flat coloring.

To invert the current selection you use the following menu command.

You can record any of the canvas: selection menu commands as action steps in a Paint Action Sequence.  So you could build up a PASeq preset that builds and uses selection masks in various ways as a part of the scripted PASeq effect.

[Ufuk Zayim]

Firs I've tryed to load Avi movie with alpha chanell.Did not work.Than I made PING sequence.It has worked perfectly. Thank you very very much.