Exposure, darkness, Ev and Preview?

[paul womack]

I am attempting to finalise the output image of my mosaic-captured
map. Part of this involves compensating for varying lighting,
since the capture session too around 2 hours
in a room with some windows.

Thanks to some hard work by Thomas Modes,
two bugs in Exposure Optmisation have been fixed,
and I now believe the Ev and Er/Eb values are as good as
they can be.

I have two precious frames where a home-brew
reference card was included.

My attempt at correction has been;

1) Load the reference images into Gimp;
correct the exposure and white balance of this
image, using the card.

(check that the Ev, Er, Eb values for both
reference images are identical)

2) Use exposure optimisation in Hugin
to co-erce all the other images onto the corrected
reference images.

(The reference cards themselves are (of course?) not visible
in the panorama, since I masked them out,
so I couldn't use the Grey Picker of the Preview tab.)

When I stitch the resulting pano, the portions
of the pano that correspond to the reference images
are MUCH darker than the reference images.

I'm using the most basic stitching option;
Exposure Correct, low dynamic range.

So - what is the pixel-value mapping from input
images to final stitch?

I also note that the Ev interface in the Preview tab of the Fast Preview seems
to have some kind of global impact on the preview, and does not simply
edit all the Ev values of the images "en masse".

BugBear