New answers tagged image-processing
I won't answer the original question about correcting the image, because in my opinion a coin is not good enough. Instead my workflow would be 1) Use a sheet of paper with a printed grid. Like a flip chart paper used in presentations. This is because you need aditional information like a 90 degree angle. 2) You can put some marks with a marker, for ...
Photoshop has great tools to correct lens distortion and has developed a lot of profiles to adjust lens distortion. Also Lightroom has an adjusting tool. If you shot your pics with a smartphone or any mpu-enabled camera, you should find angle and focus distance in the EXIF data, then you should be able with some math to achieve true dimensions.
Each program has its own algorithm for these processes and the result will be different. Indeed, programs like Photoshop have a lot of different ways to make any adjustment. And you have a lot of parameters that may adjust, not only a numerical level. Moreover, as they have told you, they work with different versions of the image file.
You don't say what camera you use but many astronomy cameras save in a corner called FITS. A python library called pyfits is quite useful for this. I've used it in my code to track bright pixels in microscopy images. It's going to be an interesting coding project unless someone has already done something very similar. Which isn't unlikely in astronomy, ...
While I agree that this belongs in some math/sci group, let me recommend ImageJ , which has some very nice tools for finding blobs and centroids of blobs. There's a huge list of software tools at Harvard-Smithsonian And in any case, this should be an opportunity for you to learn R or Python and write some automated processing code :-)
If you have some programming skills, OpenCV has all the functionality you'd need to write a program to analyse your images. For example you would likely perform some denoising before using circle detection, or bounding circles creation. This tutorial might give you a good head start and has the advantage of using Python which might be more accessible than C+...
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