Eliminating the Border Around a Generated Image

I am creating images using the rectangle() function with various line and space sizes. I attached an example image to this question. I want to eliminate the border of white that surrounds the black rectangles. (It affects my pixel count calculations.) Currently, I am just using the imcrop() function, but the cropping dimensions have to change according to the line and space sizes. Is there a more efficient way than imcrop()?

Answer 1

[jonas]

There is a function that will do this for you in one step, but I forgot what it's called. Here's a primitive solution for you!

[y1,x1]=find(BW==0,1,'first')
[y2,x2]=find(BW==0,1,'last')
BW2=BW(y1:y2,x1:x2)
imshow(BW2)

Basically you find the upper left and bottom right corners, and then crop a rectangle between those.

[Sarah]

Thanks! However, I end up with an image that repeats the image 3 times in a row. Do you know why this is and how to fix it? I've attached the image. (The workaround I implemented was to make x2 = y2, but I don't think that's a good longterm solution.)

[Image Analyst]

Is your BW really an RGB image instead of a logical (binary) image? What does this show

[rows, columns, numberOfColorChannels] = size(BW)  % Don't use a semicolon

[Sarah]

[rows, columns, numberOfColorChannels] = size(IM)

rows =

   420

columns =

   560

numberOfColorChannels =

     3

[Image Analyst]

Yep. 3 color channels - it's RGB. Try this first

BW = BW(:, :, 2); % Take green channel.

or else, if you want to keep it as a color image, do this:

BW2 = BW(y1:y2, x1:x2, :)

[Sarah]

Excellent, thank you. Now it all works well.