luminous intensity of a circular region

[Arjun247]

Is there anyway we can calculate the luminous intensity of a circular region

of an image rather than a rectangular region. The light meter function only

supports a point, line and rectangle.

I think its possible to detect luminous intesity of complete circle if we can get

all the x and y co-ordinates of all the pixelsin the circle. I am stuck at this point

for now. Any help would be greatly appreciated.

[GuenterMueller]

How about making a copy of the VI, giving it the name "Light Meter (Circle)" or "Light Meter (Oval)" and doing the according implementation on the block diagram?

Guenter

[Vladimir_Drzik]

Like this...

[Arjun247]

thanks for your help. This does solve a part of the problem.

This gives only mean, highest and lowest intensities information.

How can I get luminous intensities of all the pixels inside the circle.

[Vladimir_Drzik]

I'm not sure I understand. If you want to get the pixel intensity distribution inside the circle, you can use the "Histogram" indicator of the presented VI. You just have to link it to the connector pane, so that you can use it outside of the subVI.

Or you need a complete listing of every pixel inside the circle, i.e. an array of <x, y, intensity> triplets. That would be a bit more work to do, but also very slow for processing.

[Arjun247]

Yes that would be an ideal solution. I would need an array of x,y and pixel intensity

which would help me identify all the spots with low intensity. You said longer processig

time. Is thats less than a minute or two then great. It would work for me.

[Vladimir_Drzik]

If you just need to identify spots with low intensity, there much more effective ways to do it other than getting the pixels as an array. It might help if you post an image here and tell us exactly what you want to achieve.

[muks]

Seconds are also seen as large processing time now. As said can you attach a few images?

[Arjun247]

Hi

I am attaching the image to this mail. The small circle in the centre is the region of interest.

If you look closely the circle the centered circle has many small low intensity spots. 

These low intensity spots are my interest. I need to know how many low intensity spots

are there in the ROI.

Also what plane should be extracted for light meter function. Should it be intensity plane or

luminance plane.