Windowbox vertical bars not as dark as horizontal bars
I posted this question over on the Q8FN owner's thread but thought I'd also run it by you guys who own the big brother Q9FN model since both sets run the same firmware --
The other night I was watching an old-time B&W movie from the '40s via my Spectrum cable box's Turner Classic Movies On Demand channel which was in windowbox (AKA "postage stamp") format (substantial borders on all four sides of the displayed centered image). The top and bottom horizontal bars were typical Q8FN jet black in color, however, the two side vertical bars were not nearly as black and had a duller gray appearance to them -- not so distracting as to ruin the movie viewing experience, but distracting nonetheless. Has anyone experienced this when watching a windowbox-formatted film? Standard letterboxing looks fantastic, jet black horizontal bars with zero blooming (firmware 1202.3). I didn't try any workarounds such as stretching/zooming the picture to fill the entire screen since that can introduce PQ distortion, so I just lived with the off-black vertical bars for the duration of the film. Could this anomaly be due to a limitation with the local dimming algorithm? The exact same behavior occurs with every windowboxed broadcast I view.