Feature: Beta Channel

[Ketenks]

Everyone has done it. They copy a picture selected in entirely Alpha based background and then go to paste it into another project or layer only to be miffed by the fact that the Alpha channel was also copied and that erases everything under it. What you really wanted was just the graphics that were there to be pasted...well sometimes...but not all the time.

 

Therefore, I propose the Beta Channel as being the most ultimate transparency where it can never be selected by any means or copied but it can only be overwritten. This would allow one to save a file with a Beta background where you could easily hit Ctrl+A and Ctrl+C and then Ctrl+V and only paste the pixels that actually have anything in them.

 

What do you think about this extra channel idea?

 

A toggle could be set where one could switch from Alpha to Beta at will and many more switcher features/plugins down the road.

[toe_head2001]

Or just paste onto a new layer.

 

https://www.getpaint.net/doc/latest/EditMenu.html#8

 

[BoltBait]

Instead of Ctrl+V, try Ctrl+Shift+V

[Ketenks]

Egad! It's a common feature!

 

Thanks I needed this a thousand times already.

[Rick Brewster]

Yeah I'm not adding a beta channel in the way you describe  Layers are already the answer, as BoltBait pointed out.

Internally, some rendering code already makes use of up to 3 "alpha" channels. There's the traditional alpha that you're familiar with, which determines how translucent a color is. Then there's both coverage and clipping masks. Coverage is important when using the Overwrite blending mode, as otherwise there's no way to distinguish between "alpha is zero because the shape doesn't draw here" (which should be a no-op when compositing) and "alpha is zero because because this area should actually be stamped out as transparent" (which should reset the destination pixel to transparent -- think of drawing a circle that's filled with a transparent color). And the clipping mask comes from the selection.

[Ketenks]

Sounds cool. I'm not sure how that works but I'm guessing those are the different ways of treating the Alpha channel. Would this be the reason why some blend modes have different blends if you swap the layers?

[Ego Eram Reputo]

No that's normal. The order of the layers affects the output. A [blend] B is not the same as B [blend] A

[BoltBait]

This is due to math.

 

For example, A*B = B*A  (Multiply blend mode--order makes no difference)

And, A+B = B+A (Additive blend mode--order makes no difference)

 

But, A-B =/= B-A (Difference blend mode--order can make a HUGE difference)

[Ketenks]

That makes sense.

[MJW]

Though it doesn't change the point being made that sometimes the layer order matters, I believe Difference blend mode uses the absolute value of the difference, so for two opaque layers, the order shouldn't matter.