Some HTC handsets go 16 bit after Windows Phone NoDo update

Updating your Windows Phone 7 handset is supposed to improve the functionality of your phone, but it seems that recent updates have done everything but that. Some Samsung handsets were bricked after a minor update and now WP7 NoDo update has brought color depth problems to HTC phones. Luckily, this time the issue doesn't render your phone completely useless, but decreases image quality to 16 bits.

16-bit images translate into noticeable color banding, often occurring throughout the whole operating system. Put simply, with 16 bits you have a total of 65536 colors versus some 16 million on a 24-bit system. The difference is most noticeable in gradual color variation as you can see on the image below where the background shadow looks posterized. Alex D' on Microsoft Answers details the issue:

“I've got NoDo on HTC Trophy. Everything is okay at the moment, except a color depth. It was definitely decreased from 24bit to 16bit. I see now bandings on wallpapers and pictures. It was not like that before - the gradients were smooth and nice. Why it was changed and how I can 24 bit back?”

An unofficial fix has already been posted on the XDA Developers forum. You have to change the following keys in the registry, followed by a reboot, but try it at your own risk as Microsoft hasn't come up with an official statement just yet:

HKLM\Drivers\Display\Primary\PrimBPP dword 32

HKLM\Drivers\Display\Primary\bpp dword 32

HKLM\Drivers\Display\Primary\PanelBPP dword 32

Have you experienced the same problem? Let us know in the comments below!

source: WMPoweruser and Microsoft Answers