In Photoshop, if you lose pixel information it is usually due to your editing of a jpeg image.
As indicated the routine is to shoot in RAW and conviert to 16 bit: psd, tiff, or jpg.(16). Do as much editing as you can in 16 bit, convert to 8 bit and carefully finish your editing. Save sharpness and noise reduction work until the very end. Refer to the histogram to ensure that you are not losing pixel info. due to usually too heavy an adjustment on the editing controls.

Ronnoco