The previous "auto calibrate" button for the camera relied on a
combination of the built-in autoexposure/AWB and
some JPEG-based tweaks to get the exposure settings right.
This often led to confusing results, e.g. oscillating between green and
pink images.
I have rewritten the auto-exposure code to adjust gain and shutter
speed based on the raw image. This seems to be
very reliable, at the expense of being quite slow. That's a price I'm
happy to pay.
I have replaced both the camera's auto white balance and my
JPEG-based AWB hack with a single-shot AWB method that
looks at the raw image.
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