15inch single channel LVDS display appearing whitish. Please suggest how to overcome this issue

We have a TFT LVDS display from Sharp LQ150X1LX99

This display is a single channel.

We used the default LVDS setting for 1024X768 with the help of the below command.

fw_setenv vidargs ‘video=mxcfb0:dev=ldb,1024x768M@60,if=RGB18 ldb=sin0 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off fbmem=32M’

The display started with perfect resolution.

But the colors are whitish.

We thought it might be due to uncontrolled backlight [as we pulled it high continuously]

But then we connected to PWM controller to control it as per the datasheet.

Even after that, the display is appearing whitish at all levels of backlight luminance.

Please suggest on this issue.

link text

Images of display are attached here https://share.toradex.com/jdu6sq2u47anu85?direct