I'm wondering if Topaz Denoise actually works in 8 bit only.
Hi Dave,
No, it returns results in maximum precision (depending on the source image, and Photoshop not being fully 16-bit).
I just tried it in Photoshop with a 16-bit/channel image (with all noise reduction settings maxed out) and there were adjacent pixels that differed 1 or 2 in a given channel with the info readout set to 16-bit (so actually 15-bit +1).
It could, of course, be that the OP's source image was already compromised to less than 15 or 16-b/ch, but then I still assume that when Topaz Detail starts denoising that the resulting pixels can be '16'-b/ch. Similar with NeatImage, single digit differences.
Which is also why I hardly ever Denoise, or I even
add graininess, to avoid posterization. When printing with Qimage, dithering is taken care of automatically.
Cheers,
Bart