It sounds like a hardware issue. Typical in the LCD world if your monitor has a tint of any color you go and change the screen color temperature. Typical yellow is warm and your need to set it to neutral. However, you cannot do this on an iphone.
More than likely since the color is based on Red, Green, and Blue something is wrong with the Red and/or Green trace/cable that connects the iphone screen to the GPU (graphics processor unit).
In other words the cable connects to the display to the rest of the phone might be bad or loose.