How to calculate the area of an input image?

I want to calculate the area of the FULL binary image the user inputs is it as simple as heightXwidth if so what function does it

Answer 1

[Star Strider]

If it is a binary image (so a 2D array), the numel (link) function will do what you want.

It is equivalent to prod(size(BI)), where ‘BI’ is your binary image.

Answer 2

[Image Analyst]

If you want the number of rows and columns of the binary image, you can do this:

[rows, columns] = size(binaryImage);

If you want the number of pixels (sum total, no matter whether black or white), you can do this:

numPixels = row * columns;

or you can use numel():

numPixels = numel(binaryImage);

If you want the area of just the white/1/true pixels, then you can do

foregroundArea = sum(binaryImage(:));  % Result is in pixels.
backgroundArea = numel(binaryImage) - foregroundArea;

Hopefully one of those examples will give you what you want, because we're not 100% sure what you want.

[Warid Islam]

Hi Image Analyst,

I want to find the area of an RGB image. I was wondering if i need to convert it to grayscale image and then find the area or I can find the area of the RGB image directly? Thank you.

[Image Analyst]

No, you can find the area directly. See my attached spatial calibration demo.

Answer 3

[Jan]

This sounds like a job for the size() command. But what does "FULL" mean here and how does the user "inputs" the image?

[Elias Unk]

Yes that partially did it now i need to multiply it's 2 elements how do i get it?