Posterization on new LCD monitor…

Started Jun 9, 2006 | Discussions thread
RabidCow Junior Member • Posts: 40
Re: Posterization on new LCD monitor…

I struggled with this issue after changing from a good crt to a good LCD. Some may disagree with me, but I believe the banding is simply MORE visible on the LCD than on the slightly smeared CRT. The bottom line on the gradient is that gradients made in photoshop or other image editing programs are 8 bit per channel colour. If you make a gradient that is mostly one colour, for instance, grey, then you only actually have 255 levels of dynamic range within that image. This creates banding that SHOULD be visible on any monitor, but mostly is visible on LCD monitors due to the complete lack of focus issues.

This is all made more confusing because many lcd monitors are 6bit per channel colour with dithering added to smooth the gradients and provide approximations of colour not natively available to it. Add to that, the fact that jpeg compression can, indeed, look very similar or alternately make any actual banding more visible.

In my case, I create 3d scenes in a high end 3d program for video games as well, and saw the banding in my sky scenes whenever I used a gradient but not when I used super high bit depth "volumetric" clouds and lighting. I never saw banding in my photographs (30d images all shot in raw and processed with pscs2) on the same monitor, until I upgraded to a new version of camera raw which had "auto" settings enabled. Those auto settings were making enough changes in the image to cause banding to occur. I disabled all of the auto settings and set everything for the least change in the image possible and the banding disappeared. This is all with the same LCD monitor. I now use adobe raw but output only the flattest lowest contrast images with no sharpening, no noise reduction, linear curves etc and then do one adjustment of the curves in photoshop in 16bit per channel and then one application of unsharpmask radius .5 280. The images are georgeous now with no banding (I can add banding when I compress a jpeg for the net, lol). Good luck!

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