Problem on 'bitand' method

Hi friends,

I have problem on 'bitand' method when create marker image using mask.

 I2 = im2bw(I1,0.8);  %%Thresholding image(Create a mask)
I2Cmp =  ~ I2;  %%Invert the mask
marker=bitand(1,I2Cmp); %%Create marker image

There is an error when creating marker.

??? Error using ==> bitand Inputs must be non-negative integers.

How would I apply bitand for creating a maker ????

[David Young]

Could you explain what the marker image should be? It's not clear why you would want to use bitand at all in this context, and I wonder if you need something completely different. I2 and I2Cmp are logical arrays, so there is only one bit of information per pixel anyway.

[nayomi ranamuka]

Marker image is the result when apply bitand method for I1 and I2Cmp images. I want to ovelay the inverted image of I2 on I1 .

How would I apply bitand method ?

Answer 1

[Laura Proctor]

I don't think that you actually need to use BITAND. I think what you would like to do is create marker that consists of all ones and zeros. To do this, just use the following code to create a logical array:

marker = I2Cmp > 0;

Then, to overlay this on I1, simply use element-wise multiplication:

Iresult = I1.*marker;

[Steve Eddins]

I2Cmp is already logical, so the first line of code in this answer is not necessary.

Answer 2

[Steve Eddins]

The general answer is to use the elementwise logical operators &, |, and ~ instead of bitand and bitor to do this sort of manipulation with binary images.

To "overlay the inverted image of I2 on I1," as you say, you would do this:

marker = I1 | ~I2;

[David Young]

Steve, I don't think I1 is logical.

[Steve Eddins]

David, you're right, sorry.

Answer 3

[nayomi ranamuka]

This is my solution. marker=bitand(im2uint8(I1),im2uint8(I2Cmp));

Thanx for your answers.

Answer 4

[Steve Eddins]

Here's a different kind of overlay:

Iresult = I1;
Iresult(ICmp) = 255; % assuming I1 is uint8

This version turns all the marker pixels white and leaves the others alone.