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How do I calculate the area with matlab (unit : m*h)?
Don't take the blue,red lines into account, what's the simplest solution to calculate the area of the green box unit(width and height in pixels) with MATLAB?
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72answers:
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A:
Since the grid is perfectly well aligned in the horizontal/vertical, you can use the following algorithm:
- Extract the green channel
- Threshold the image such that there are 1's wherever there is a green signal, and 0's wherever there is white
- To find the spacing in x
- Sum the thresholded image along y
- Find the local maxima in the summed array
- Count how many pixels there are between two local maxima.
- Repeat for y
Jonas
2010-06-07 14:08:33
This is not accurate,since it doesn't always happen to be N times of units in total.
2010-06-07 14:14:46
Standard operation is to remove outliers and take average.
yuk
2010-06-07 14:37:01
Right, but in this case it's known before hand that each box is of the same size, so I want to calculate it exactly.
2010-06-07 14:43:11
The average of the distances will converge toward the exact distance between peaks. Also, you can calculate the position of the local maximum with sub-'pixel' accuracy (e.g. by fitting a Gaussian into the peak and measuring the position of its center), so that the average converges even faster.
Jonas
2010-06-07 15:30:17