using greythresh and im2bw

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Douglas Brenner
Douglas Brenner on 6 Nov 2016
Edited: Image Analyst on 6 Nov 2016
Figure 1 is great but BW is all black. Thoughts? Thanks
figure (1)
scaled = 255 * width/MAX;
level = graythresh(scaled)
BW = im2bw(scaled,level);

Accepted Answer

Walter Roberson
Walter Roberson on 6 Nov 2016
BW is logical, just 0 and 1. When you uint8() that, you are creating an image with just uint8(0) and uint8(1), which is too dark to be visible.
You are also doing the grayscale conversion on a double array that is out of range for valid double coefficients, and that is affecting your output.
figure (1)
scaled = 255 * width/MAX;
scaled8 = uint8(scaled);
level = graythresh(scaled8);
BW = im2bw(scaled8, level);
Image Analyst
Image Analyst on 6 Nov 2016
Edited: Image Analyst on 6 Nov 2016
Douglas, what is "width"? It's not a scalar is it? It's a 2 or 3-D image, right? Otherwise scaled will not be an image - it will just be a single number.

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