My old HTC M7 developed the pink purple tinge fault that is common as the camera module over heats and becomes permanently damaged. So I bought a replacement camera module on eBay for £9.99 watched a couple of Youtube videos and had the new camera fitted in about 30 minutes. Fired it up, and hey presto camera works a treat now.
You can check out the HTC M7 camera modules for sale and these Youtube videos will show you how to replace the module.
This is the only way to correct the pink purple tinge problem. Software and setting fixes are a waste of time as the module is fried.