Hi Tanvi and Vitaliy,
I know that this does not work quite well yet, but if I take the photo that Tanvi posted
img = Import["~/Desktop/Eclipse.jpg"]
and crop it a bit:
img2 = ImageTrim[img, {{447.386`, 409.278`}, {513.381`, 344.818`}}]
I get:
The question that also relates to Sander’s question in Vitaliy’s post is: how much of the sun was covered. The idea is to cover the crescent by a disk:
MorphologicalComponents[Binarize[img2, 0.4], Method -> "BoundingDisk"] // Colorize
then determine the shape of the crescent itself:
MorphologicalComponents[Binarize[img2, 0.4]] // Colorize
and then calculate the respective areas:
full = ComponentMeasurements[MorphologicalComponents[Binarize[img2, 0.4], Method -> "BoundingDisk"], "Area"][[1, 2]]
(*1206.5*)
crescent = ComponentMeasurements[MorphologicalComponents[Binarize[img2, 0.4]] // Colorize, "Area"][[1, 2]]
(*311.75*)
The ratio of which is:
crescent/full
This gives a covering of about 74\%. This number is only a rough estimate. The fitted disk is not quite right as you can see in this plot:
ImageMultiply[img2, ColorNegate@(MorphologicalPerimeter[MorphologicalComponents[Binarize[img2, 0.4], Method -> "BoundingDisk"], 0.2] // Colorize)]
The black circle is the estimate of the shape of the full sun, which is obviously not quite what we want.
Cheers,
M.
PS: Tanvi, thanks a lot for posting the photos!