There should be no problem using the Blend Mode Behind in a 16bit image.
And you seem to be misunderstanding what a 64bit application means.
So, please tell me, if this is possible, how a 64-bit image file can be created in this app.
In Photoshop there are no »64bit images«, 32bit per Channel is tops, at least so far – and I doubt anything more would be useful.
Something on 32bit and 64bit Systems:
Thanks, friend, for your two helpful replies. I shall look a the links that you provided, later, when there is more time. However, in the list of blend modes shown in the Layers panel of a 32-bit image, I did not see any option to use Behind mode.
Probably you are right in suggesting that I misunderstand what a 64-bit application is. All this kind of stuff is far above my head. However, I had to frame my questions according to my limited understanding.
For which operation do you intend to use the Blend Mode?
Painting with »Behind« in a 32bit RGB image seems to work fine.
I created an image, filling it with blue. On top of that, I placed an empty layer. In that empty layer, I scribed a circle, and filled it with red. Then, in the transparent layer with the red circle in it, I typed some words in green, thinking that it would be possible to opt for Behind mode with the text. However, Behind was not in the list of blending modes. Perhaps there was something that was not being done aright, but, if there was, I don't know what it was.
Could you please post a screenshot with the pertinent Panels (Layers, Channels, Options Bar, …) visible?
Why not just place the Type Layer behind the Layer with the circle?
The reason you're almost never seeing Behind is that it's only available for brush tools. It controls how pixels apply as you paint. It only appears in the options bar when you have a painting tool selected, and for that reason I don't think it ever appears in the Layers panel. Same for the Clear blending mode.
To use the Behind blending mode, first select a pixel layer in the Layers panel that isn't the background layer and has transparent areas. Then select a painting tool like Brush or Clone Stamp.
Details about that blending mode are on this page:
The reason you're almost never seeing Behind is that it's only available for brush tools.
Also Edit > Fill.
Thanks very much for clearing up this conundrum. I love to learn about Photoshop (whether I need to for practical purposes, or not), and this problem was driving me crazy.
Thanks friend, for the extra information. Also, for so persistently sticking with this enquiry.