Re: find a circle
Posted by Nathaniel Ryckman on Apr 01, 2011; 11:35pm
URL: http://imagej.273.s1.nabble.com/find-a-circle-tp3684935p3684944.html
I was playing around with the image you provided for fun. Here are a few things that I was observing:
Observations:
1) The intensity is all over the place for all 3 channels. Thus, I wouldn't pursue separating the circle using autothresholding alone.
2) The gradient around the edges of the circle seem to define the border of the circle upon introspection.
3) The red light blends into the circle's color around the bottom right corner and has an intensity that seems to diminish the blue and green light that was detected by the camera. In other words, the gaps that you see in the image that I provided are because of areas around the circle without a steep gradients to define the border clearly. My guess is that the human eye somehow extrapolates that data.
What I did:
1) Split the channels
2) Ran subtract background (50 px)
3) Find edges
4) Duplicate a channel, mean (150 px), subtract duplicate from original
5) After doing 2-3 for each channel, I used stack focuser to create a composite
Things you could try to do:
1) Weight green and blue images by increasing the brightness on half of those images (where the holes are in the red image, south-east)
2) Run max intensity instead of stack focuser
3) Dilation/erosion to fill in gaps that are not detectable on any channel
4) ?
The reasons for step 2 and 4 in the in the "What I did" section, is found here:
http://www.macbiophotonics.ca/imagej/image_intensity_proce.htm
Good luck!
URL: http://imagej.273.s1.nabble.com/find-a-circle-tp3684935p3684944.html
I was playing around with the image you provided for fun. Here are a few things that I was observing:
Observations:
1) The intensity is all over the place for all 3 channels. Thus, I wouldn't pursue separating the circle using autothresholding alone.
2) The gradient around the edges of the circle seem to define the border of the circle upon introspection.
3) The red light blends into the circle's color around the bottom right corner and has an intensity that seems to diminish the blue and green light that was detected by the camera. In other words, the gaps that you see in the image that I provided are because of areas around the circle without a steep gradients to define the border clearly. My guess is that the human eye somehow extrapolates that data.
What I did:
1) Split the channels
2) Ran subtract background (50 px)
3) Find edges
4) Duplicate a channel, mean (150 px), subtract duplicate from original
5) After doing 2-3 for each channel, I used stack focuser to create a composite
Things you could try to do:
1) Weight green and blue images by increasing the brightness on half of those images (where the holes are in the red image, south-east)
2) Run max intensity instead of stack focuser
3) Dilation/erosion to fill in gaps that are not detectable on any channel
4) ?
The reasons for step 2 and 4 in the in the "What I did" section, is found here:
http://www.macbiophotonics.ca/imagej/image_intensity_proce.htm
Good luck!
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