Originally Posted by CleCakYngMfd
The Backlight, and especially the Contrast are pretty HIGH. Depending on source/content, there will be 'overexposure' or 'over-driven' issues. This has been my experience when driving the Backlight and/or especially the Contrast too high.
Agreed on the Contrast. While the 235 level is supposed to be peak level for video, almost all video has peak levels that use some of the headroom between 235 and 255. On most displays, including the Vizio, the red, blue, and green sub-pixels of the display don't all peak at the same point. So if you don't set contrast low enough, a bright white in that 235 to 255 range will cause a single primary color to peak before the others which then results in a color shift. So the brightest whites will not be the same color as the not quite so bright whites. While it sounds like this will simply make the brightest whites not look right, human visual perception will actually attempt to compensate to a degree and shift the perception of the colors of everything else on screen when this occurs as well.
The highest level I could set the contrast without clipping any of the primary colors below level 255 was 65. Red began clipping at 66. Blue was difficult to determine because it does not exhibit a linear increase in brightness. The banding is bad enough that some lower number brightness levels of blue are displayed as brighter than the next several brightness levels above them. If my colorimeter was still working correctly, I would use it to verify that white at the 255 level was the same color as all whites at lower levels (D6500). When it starts to stray from that, the contrast is set too high. I do advocate setting the contrast as high as possible without clipping any of the primary colors, therefore using the maximum dynamic range of the display, and then adjust the backlight level to achieve the desired overall picture brightness.
High backlight levels shouldn't cause any color shift or undesirable picture issues other than simply having too bright of a picture. Backlight levels should not cause any color issues unless the backlight changes color with variance in backlighting level (which it shouldn't, and would cause significant color issues with smart dimming if it did). Determining if there was any color shift with changes in backlight levels would require a colorimeter or photo spectrometer.