T-i-m wrote:Actually my scene is not typically back-lit but the important parts are in the center of the frame and I thought I read in the documentation that 'backlit' is "the same" as what on DSLR is normally refered to as "center weighted" metering. Where the light metering algorithm looks more on the middle of the frame than on the outer pixels.
I'm not the expert on the AGC algo, but looking at the numbers that each mode results in, I don't see how using backlit mode would be helping.
All modes appear to be setting up two regions - a centre one, and an outer. In all cases the weightings of the two regions are the same, but they differ in the size of the centre region, backlit having the largest centre region (0.3 of the width), then average (0.25), and finally spot (0.1). There then appears to be some interesting logic to determine based on the stats from those regions to determine whether the scene is backlit or not, and alters the gain/exposure calcs accordingly. Selecting backlit alters the thresholds at which it concludes the scene is backlit.
I suspect that you selecting backlit when the scene isn't is confusing the logic and hence doesn't adapt. Average mode already has a modest amount of centre weighting anyway, so is probably just as appropriate.
As to documentation saying anything, I'm not aware of anyone with in-depth knowledge from Broadcom having defined the detail of any of the algorithm settings. Others may have made their own conclusions by experimentation, but that won't be authoritative and could be plain incorrect.
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