Why image appear black and white image?

i convert 3 d image to 2 d image. Then I have used the imwrite function. But image was appeared the black and white image. Why?

[KSSV]

You converted to black ad white and used imwrite.

[Rik]

What else did you expect? Or you mean actually black and white, not grayscale?

[hla hla myint]

Yes, I wish actually grayscale.

My code is following

a=niftiread('filename');
b=(a(:,:,100,1));
c=imresize(b,[120 120 ]);
imwrite(c, v.jpg);

out image is black and white image. I wish grayscale image.

[Image Analyst]

What is the class of (the poorly-named) c? Is it double or uint8 or uint16?

You forgot to attach your file so we can't run your code.

You need to put v.jpg in single quotes otherwise it will think that v is a structure and the jpg field of that structure is a character array, which is not what I think it is.

imwrite(c, 'v.jpg');

Do not use JPG for image analysis - it introduces bad compression artifacts. Use PNG format instead.

imwrite(c, 'v.png');

What does this show in the command window

whos a
whos b
whos c

[Rik]

"Do not use JPG for image analysis - it introduces bad compression artifacts. Use PNG format instead."

I whole-heartedly agree, but in medical imaging it appears to be common to convert perfectly good 12 bit precision DICOM files to JPEG. I don't understand why, but that seems to be the standard. Judging by the use of niftiread I assume this is a medical purpose as well, meaning this might just be conforming with the input requirements of the next step in the pipeline.