how to find the area of black region in image....?

I have to find the blank area in the image...ie its value is 0..how to find the area..help me out...

Answer 1

[Andrei Bobrov]

s = regionprops(YourImage == 0,'Area','PixelIdxList')

add

I = imread('44298455.png');
i0 = im2bw(I,graythresh(I));
s = regionprops(i0 == 0,'Area','PixelIdxList')

[Meena]

this is allso finding the area for all 0 in the image sir...i upload my image sir..in that i have to segment the blank region.....

[Walter Roberson]

Where did you upload your image to?

[Meena]

http://imageshack.us/photo/my-images/528/44298455.png/

this is image

[Walter Roberson]

Is it the portion outside of the oval whose area you are trying to find?

Answer 2

[Walter Roberson]

sum(YourImage(:) == 0)

[Meena]

not for whole image sir..I have to find the blank region first i.e segment the parts alone and then the area sir

[Walter Roberson]

Are there parts of the image which contain blank areas that you do _not_ wish to have included? The code I gave does not give the area of the whole image, only of the blank area.

Answer 3

[Image Analyst]

Try this:

binaryImage = grayScaleImage == 0;
measurements = regionprops(binaryImage, 'Area');
allAreas = [measurements.Area]

allAreas will be an array of areas. Each physically separated, isolated, black region will have its own area in the array.

[Walter Roberson]

Is a bwlabel() needed before the regionprops?

[Image Analyst]

It used to be, but not anymore. It will label it internally. That change occurred around 2 or 3 versions ago. Usually (from habit) I still call bwlabel explicitly before regionprops though.

[Meena]

but not getting the exact area values

[Meena]

pls tell me is there any otherway to find the no of blank or the area of blank spaces