Originally Posted by erkq
This is OT but I am right in the middle of this sort of adjustment. I'm losing shadow detail with my rs20 so I bumped the lower gamma. Sounds like I should turn up the brightness instead, providing I don't get white crush on the other end.
I'll delete this post if/when you respond.
I think you might have adjusted the right thing with the gamma.
As RS20s age the gamma changes and what you describe is a typical symptom. So in your case, I think you did the right thing. There is no substitution of course for adjusting gamma with meter and software.
If you were to raise brightness, I suspect, you will actually be lifting the black level of shade 0 (and the missing shades with it) and therefore all you would achieve would be loss of contrast ratio.
To put it another way. If you drop brightness, you will get black crush. The more you lower it, the more shades will become the same as shade 0, black.
As you raise brightness, you lift the black level making it less black, and you squash all the shades closer together, reducing the on/off contrast ratio.
The easiest way to set brightness, is to make sure the room is completely dark. Use a test disc to output a completely black image (0 IRE). Set the brightness to something like +10. Then keep reducing it, until you note that the black level no longer changes as you adjust. That point where moving it anymore won't change black, is the correct setting. And in every JVC so far that I have seen, it has been -1, 0, or +1
Having set brightness correctly and still losing the lower shades, or they are all merged together so you can't distinguish easily between shades 0-10 then its gamma that needs adjustment.