In the image you'll see a glassy blob object with a gray background plane. I
tried sky_sphere and background {}, with similar results, if the AA
threshold is 0.1 or lower. AA values typed onto the two examples. Once the
AA value is high enough the blocky artifact will disappear. Apparently gamma
related somehow.

Curiously, I hadn't noticed such a thing happen before. At first I thought
it was my LCD screen, working at no more than 18-bit color, or maybe the
video driver. Anyone else want to try confirming this as a possible problem?

Bob H.

A simpler SDL for testing is:

global_settings { assumed_gamma 1 } // no correction, no artifact?

camera { location -3*z }

light_source { -100*z, 1 rotate <45,45,0> }

background { 0.5 }

sphere { 0, 1 pigment { rgb 1 } }

/* be sure to use AA of 0.05 or thereabouts to see the affect */

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