Threshold ranges to BW image

Hi,

I have a black and white image, and I am wanting to apply three different thresholds of 105-168, 170-200, and 120-140 to calculate the surface area coverage of three different sections within the image.

Could you please tell me how I could achieve this, in terms of the code or a link where I cold read up on this?

Thanks in advance

Syed

Answer 1

[Image Analyst]

Try this:

binaryImage1 = grayImage >= 105 & grayImage <= 168;
binaryImage2 = grayImage >= 170 & grayImage <= 200;
binaryImage3 = grayImage >= 120 & grayImage <= 140;

areaFraction1 = sum(binaryImage1(:)) / numel(grayImage);
areaFraction2 = sum(binaryImage2(:)) / numel(grayImage);
areaFraction3 = sum(binaryImage3(:)) / numel(grayImage);

[Ahmed]

sir, from the image below, how to create a graph for threshold B&W. Let say i only want to create a graph for the subplot(2,2,4) image. Can u help me sir,

[Image Analyst]

What do you mean by "graph"? Like a line/curve plot? Or a bar chart? Or what?

[Ahmed]

like histogram.

[Image Analyst]

The 224 subplot (lower right) looks like a binary image so the histogram will have only bins for 0 and 1. You can use imhist(). Not sure why you want it though.

[Ahmed]

oh, gosh. u r right. i'm not sure also. tq!