Matlab needs to calculate distance and find pixel size

Hi, I need to do image calibration between two known points on an image.

Let's say that we have those two points [130,799] and [602,799], where the first are rows and then the columns. I know I need to use the euclidean distance equation like this

So assuming

y1 = 130
y2 = 602
x1 = 799
x2 = 799

distanceInPixels = sqrt( (x2-x1).^2 + (y2 - y1).^2);

How do I combine all those stuff and finally get the calibration factor of mm/pixel.

Please help.

Answer 1

[Mark Sherstan]

You need to know the distance between those two points. I attachted part of a presentation where I did just that. I placed three "calibration blobs" at the start of the video. Masked the image for green, then red, then blue to find the "blobs". Using the euclidean distance equation you provided I took the known centroid-centroid distance divided by the pixels for each color mask and then averaged the results. Let me know if you have any further questions but you are almost there!