Trying to count pixels in a mask

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Sam
Sam 2011-8-5
I have a variable called MASK2 and want to count the pixels in it using the following layout that has been given to me
function number=pixcount(BLANK)
number=0;
for n=BLANK:BLANK
for m=BLANK:BLANK
if BLANK(n,m)==1
number=number+1;
BLANK
BLANK
BLANK
So I have written the following
function number=pixcount(MASK2)
number=0;
for n=1:1500
for m=1:977
if MASK2(n,m)==1
number=number+1;
end
end
end
but get an error message on line 5 saying Input argument "MASK2" is undefined.
Error in ==> maskloop at 5 if MASK2(n,m)==1
What am I doing wrong? Thanks.

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回答（2 个）

Friedrich
Friedrich 2011-8-5
Hi,
sounds like you are calling your function without an input like pixcount(). Try to pass something, like pixcount(rand(1500,997)).
But in general you can count 1 a bit faster, e.g.
number = sum(sum(Mask2==1))
If Mask2 is a logical matrix than you can do
number = sum(sum(Mask2))
Image Analyst
Image Analyst 2011-8-5
You can't just run that function without calling it with a defined matrix. You need to call it from another function (if it's in the same file) or from a separate script. For example in script1.m:
m = rand(100);
mask2 = m > 0.7;
% Now call the function:
pixelCount = pixcount(mask2);
Then in pixcount.m:
function number=pixcount(MASK2)
number=0;
[rows columns numberOfColorChannels] = size(MASK2)
for n=1:rows
for m=1:columns
if MASK2(n,m)==1
number=number+1;
end
end
end
And, like Frederich said, that's not an efficient way to do what it ends up doing.

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