3.5 inch tft lcd screen module ultra hd 320x480 free sample

I purchased 2 screens and both have similar issues with colors. They are displaying content, but problem is that colors are not correct most of the time. It looks like always one of the RGB component is missing or not intensive enough, and it is totally random. Every time I turn on LCD it shows different spectrum and stays in that spectrum until next power cycle. I"m sure that it is not problem with libraries or my code because in rare occasions these panels shows correct colors and stays in correct color spectrum until next power off/on. I have others LCD screens which physically look like these (both 3.5" and 3.2") and these work correct all the time. I take photos of 4 consecutive powering of the same display. The most prominent difference can be seen on bar graph on the left (it should be pale yellow in original and here colors are from pale grey to yellow-greenish to purple-bluish). I cannot blame seller for this problem because displays came in OEM packaging and undamaged.

Ok, I played couple of days with these screens trying to achieve good and consistent color spectrum. I think that I finally made it to work. It seems that these displays came from factory with somehow wrong default settings for gamma and refresh rate. If you experience similar issues try to change data values in following commands: C0h, C1h, E0h, E1h, E2h, E3h and 36h. For example, I changed values for C0h to 0x1F for first register (sets VREG1OUT for positive gamma to 5.500V) and 0x01 for second (sets VREG2OUT for negative gamma to 3.625V). Please look at new picture below. It is much better than before. According to these new findings I will rate this product with 4 stars now...