Convert input image to binary

How would I manually convert an image to binary by setting all values less than 100 equal to 1 and all else equal to 0?

[Chad Greene]

What exactly is your question?

Answer 1

[Image Analyst]

Try this

[rows, columns, numColorChannels] = size(a);
if numColorChannels > 1
  % Convert color image to grayscale.
  a = rgb2gray(a);
end
binaryImage = a < 100;
imshow(binaryImage);

If you need more help, attach circlesBrightDark.png.