How would one correct the photos 7748 and 7749 to look like
7741 and 7751? And at the same time preserving the sunrays?
http://www.funet.fi/~kouhia/7748.jpg (automatic mode)
http://www.funet.fi/~kouhia/7749.jpg (manual mode with less exposure)
http://www.funet.fi/~kouhia/7741.jpg (automatic mode)
http://www.funet.fi/~kouhia/7751.jpg (automatic mode)
Both my attempts uses first the curves tool and then adds saturation,
but I have no idea what would be correct/best operations.
http://www.funet.fi/~kouhia/7749mod1.png (my attempt 1)
http://www.funet.fi/~kouhia/7749mod2.png (my attempt 2)
The curve was designed using the rules:
(1) The top values, i.e., sky, are ok and thus curve y = x should be
applied at top.
(2) Exposure time was low at bottom+middle and thus curve y = 3x (for
example) should be applied there. The linear function y = 3x means
that the exposure time is tripled.
(3) Some smooth piece of curve connects the bottom and top segments.
In practise, I had to use only 4 control points in the curve
because more points meant wavy curve. That limited the smooth
piece of curve between the bottom and the top greatly.
Better spline would be needed in the curve tool, like what is in the
path tool (but note that I have GIMP 1.2.3).
Saturation was added until the photo looked ok enough. The saturation
worked like a magic. I wonder why it seems to be needed. Is it a camera
property that low exposure works differently than long exposure?
Or is it property of the curve tool? I.e., a better curve tool would
always add the saturation.
The image 7749mod2 looks tolerable, but the noise is a big problem.
I guess better camera would solve that. I could also try the HDR
photo techniques as I found Olli's dynamic range extender. I have
a code somewhere which I obtained from a person who wrote similar
photo combiner for multiple photos, and wrote a Siggraph paper on it.
Though, digital cameras could have a sequencer which can be programmed to
take multiple photos as fast as possible with different settings
(exposure, focus, zoom, etc). No patent pending.
for developers of open source graphics software
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