The problem was in fact in the changes made to blend_ramp() func at rev42164. The checks on green pointer (if(g) {...) were checking the existance of a valid value (i.e. if input color was rgb or only shades of grey in r pointer), but as we get now a full float[3] pointer, this test is no more possible. And doing if(r_col[1]) {... was wrong, as it only broke things in case green was 0.0 (which was the case with the generated glare color of bug report). So, just removed all those tests!