How to change alpha value in curve adjust method?

[super_ilad]

Hi , we all know we can adjust RGB value by curve method , cause it is more smooth,but how can i adjust alpha value in the same way ?

In the beneath example, the shadow part i have noted in red dot have opacity 75%, 

and farther part of shadow has a lower alpha value ,in this case , it is 11%

i now certainly can adjust the darker shadow part by eraser tool manually , but is there any way to finish it by curve tool like adjusting RGB value ?

Until now , i dont really find a way to adjust alpha value by curve , in normal curve tool, it only influences RGB value , but the alpha value doesn't change at all! 

[c.pfaffenbichler]

I understand what yuo mean (edit: at least I think so), but in Photoshop that is called »transparency« and not »alpha«. 

The only way I can think of is 

• Layer >Layer Mask > From Transparency 

• select the resulting Layer Mask

• apply the Adjustment on that 

[super_ilad]

Ya, that counts, thanks!

[rayek.elfin]

I don't think this is directly possible: Photoshop hides the transparency channel, or at least, it is not possible to affect transparency directly - only through layer masks, for example. Transparency/alpha is not adjustable via the curves without converting it first to a layer mask.

Another option is Layer>Layer Mask>From Transparency. It will convert the layer's transparency to a layer mask. Then Alpha becomes available in the Curves. Bit of a work-around, though. And it will not work with multiple layers.

It's a known legacy limitation in Photoshop. In other image editors curves do support direct adjustment of the transparency values, though. Would be nice if PS gets this option at some point.

*oops, c_pfaffenbichler beat me to it.

[PECourtejoie]

Rayek, did search or create a thread on the topic on https://feedback.photoshop.com site, watched by Adobe staff. Make sure to provide as many relevant details as possible, on how it could improve your workflow...