LCD 240x160 Brightness , contrast, and gamma wont adjust

OpenMV Products
1

i need to lower the brightness and wanted to adjust the contrast .
There is a string which supposebly adjusts all 3 on one line i had tried but it did not adjust.
Mainly needing to lower the brightness and adjust contrast .

2

https://docs.openmv.io/library/omv.image.html#image.Image.gamma