Alpha channel with Source Area PSC set to pallettize

[Heather]

HI,

I am still confused about how to work with Alpha channels.

I am using an Autopaint Impression brush and the Source Area set to Paint, and have the Brush Type set to Source Alpha Brush. it recognizes the alpha channel that I have and keeps the area white (no paint).

When I change the Source Area to palettize instead of paint, but keep the Brush Type to Source Alpha Brush, it does not recognize the alpha channel and paints everything, including the alpha channel.

What am I missing or doing wrong?

Thanks,

Heather

[Synthetik]

I would not expect changing the source area to palletize to change the way the brush type works. Can you tell me the specific paint preset category and preset name you are using.

[Heather]

Well, I could not emulate the problem now, so I am chalking it up to my user error.

However, when I try to paint inside of the alpha channel, I am not able to mask out the background (alpha).
Can you please walk me through what I am doing wrong? 

I am using the Impression brush, with brush type set to Source Alpha brush. Is there another step that I am missing? 
See screenshot. Thanks!
Heather

[Heather]

image:

Screen Shot 2016-11-22 at 8.45.53 AM.png

[Synthetik]

The Brush Type called 'Source Alpha Brush' refers to the alpha channel in the Brush Source. So it's an alternative to the Brush Type called 'Source Brush', which uses the luminance component of the rgb image in the Brush Source to define the brush used by the paint synthesizer. Source Alpha Brush uses the alpha channel in the Brush Source to define the brush used by the paint synthesizer.

It sounds like you are mis-interpreting this to refer to an alpha channel in the source image maybe?

If you want to mask out painting based on the alpha channel of the source image, there are several different ways to do it. You could set the selection buffer to the source alpha, and then turn on masking, then paint. Or, you could edit the paint preset, using controls in the Path Start or Path End control panel to drop out path start points in alpha masked areas, or end path painting in alpha masked areas.