This video explains the impact of the new gamma controls that JVC has implemented on their UHD capable projectors. While the video shows the gamma behavior based on High Dynamic Range enabled signals, the information can also be applied to standard dynamic range material for regular HD programming.
The revised gamma controls consist of three elements, the Picture Tone, the Dark Level and the Bright Level. The Picture Tone control shifts the entire image / curve to the right if you set the control to minimum. The shift is to the left or much brighter if you maximize the control. The images demonstrate this brightening and darkening of the overall image.
The goal with the Picture Tone control is to achieve a gamma curve that is similar to what is shown here to the left. So in our case, the optimal value is somewhere between 0 and +16.
With the Dark Level control, we get more of an impact on only the dark end of the image. The control shifts the dark end to the right side if you decrease the values making the image darker. The shift is to the left if you increase the values. The goal is to get the Picture Tone as close as possible first and then fine tune the dark level control.
With the Bright level control, we get more of an impact on only the bright end of the image this time. The control shifts the bright end to the right side if you decrease the values making the bright end darker. Shifting to the left if you decrease the values. The theoretical goal here is also to fine tune the graph to track as tight as possible with the gamma curve.
Remember that when all is said and done, what matters is what the pictures look like rather than graphs. The end results need to be tweaked based on real HDR content to get a proper look to the image. Don’t blindly rely on what graphs tell you.