I try to merge layers, I will lose the mask that was on one of the layers.

Well, naturally.

Instead of merging you could try converting the batch to a Smart Object. Bloats file size but the Layer Masks would still be available in the SO.

PECourtejoie wrote:

 

Trevor, why not to a channel? Isn't it lighter? (but a layer might be faster to get to, according on how you set up your workspace)

That's fair comment Pierre, and I have Channels and Paths panels permanently available.   But can I create an Alpha mask without having to click on 'Save selection as Channel'?  Is there an existing keyboard shortcut?

OK.  I had not thought of right clicking, and as you say, there are heaps of options, and they are obviously going to change with context.  I wonder if I can break the habbit though? 

One small note:  Every selection specifically is 8 bits/channel no matter what the document depth.  I say this because selection masks are always provided to plug-ins in 8 bits/channel format.

So my point is that if you're editing deep (e.g., 16 bits/channel) image data, and whatever workflow you're using uses a selection as part of it, you will have quantized the data to 8 bits at some point.

You can prove this to yourself if you're skeptical...  Make a radial pure grayscale gradient in a 16 bits/channel document.  Then control-click on one of the color channels to make it a selection, and Save the selection in a channel.  Now Copy the data from that channel and paste it over the original gradient as a new RGB layer.  Set it to Difference blending and greatly enhance the brightness of the differences...

-Noel

I just thought I'd mention it since some people do use the selection process as a stepping stone in their workflow to make things happen in their images, and the quantization might matter if the data is subsequently stressed a good bit.  As an example, such stressing might occur, for example, when digging very dim data out of astroimages.

if you can prove that's not true, I'm sure the engineers would rethink that. I've never been able to prove it...

Nor have I ever had any problem with being able to select things at roughly 0.4% intervals.

But at this point I wouldn't bet that Adobe could be convinced to embark on changing it for any reason, even if one showed a way that it was turning their images into hamburger.  The selection mask strikes me as being at the very heart and core of Photoshop - i.e., ingrained in the very oldest code - and stuff like that no doubt has accumulated a lot of implicit assumptions (e.g., byte addressing shortcuts) all throughout those 4 to 5 million lines of code you mentioned.

-Noel