Black & white image segmententation and automatic counting

Hello,

I'm new to MATLAB and wondering if i can do a special automated image analysis as below:

• Detect white points on image
• Count all points
• Measure points
• Divide the frame by lines and detect if the line cross the abovementioned points

Please respond if it is possible with some hints if so.

Thank you

Answer 1

[Soya AOKI]

Hi

(1) Detect, Count and Measure points

if all points are circular, Find circles using circular Hough transform is useful I think.

And MATLAB has a lot of segmentation methods.

(2) Detect if the line cross points

Circular detection returns center(x,y) and radius R. So you can detect if the line cross points by following code I think.

if ((center_y + radius) is above line & (center_y - radius) is under line)
    cross_flg = true
else
    cross_flg = false
end

thanks

[Ali Noun]

Thank you Soya AOKi,

This is very helpful, actually points are not perfect circles and can have all shapes, any ideas?

[Soya AOKI]

I got it.

All your images are RGB, Gray scale or Binary?

[Ali Noun]

Hi

images are RGB, could be in gray scale if needed.

Thanks

[Soya AOKI]

Thanks for your info.

(1) Detect, Count and Measure points

For all shape, you could count and measure location and area by these method.

・https://jp.mathworks.com/help/images/examples/measuring-regions-in-grayscale-images.html

・https://jp.mathworks.com/help/images/calculate-region-properties-using-image-region-analyzer.html?lang=en (App)

(2) Detect if the line cross points

You can get binary image like this. 1 means white(points) and 0 means black(not points).

0 0 0 0 1 1 1 1 0 0 0 0 0

0 0 0 1 1 1 1 1 1 0 0 0 0

Line → 0 0 1 1 1 1 1 1 1 1 0 0 0

0 0 0 1 1 1 1 1 1 0 0 0 0

0 0 0 0 1 1 1 1 0 0 0 0 0

"1 (points) exists on line area" means "the line cross points". so you can detect if the line cross points by checking if there is 1 on line area I think.

And difference of neighboor pix on the line is following.

0 -1 0 0 0 0 0 0 0 1 0 0

Maybe you can count points crossing line by counting 1 or -1 in the difference.

Or if line is shown as red on image (like your image), you could detect if the line cross points by R component of the original image.

(Please excuse me for little bit confusing explanation.)

Thanks.

[Ali Noun]

Thank you