how to convert 0-255 scale to 30-170 scale in a grayscale Image?

I have a 112*112 matrix in matlab which I am plotting as a grayscale image. I am using imacesc for this purpose and the resulting image is on a normal grayscale image, 0-255. However, the results are not quite pronounced in this scale and I want to rescale my image on a scale of 30 - 170 since most of my pixel values are in this range. I am using rescale for this purpose but it is not working. Can anyone help me with this issue?

Answer 1

[Image Analyst]

Try telling imshow() the display range:

imshow(grayImage, [30, 170]);

but rescale() should have worked also:

imshow(rescale(grayImage, 30, 170), []); % Use [] because I think rescale() returns a double.

[Umair Bashir]

Thank You for your reply. i have tried both these functions but they are not having any effect on the pixel intensities, instead they're just chaning the colormap range.

[Image Analyst]

Correct. If you actually want to change the gray scales, you'd use imadjust():

grayImage = imread('cameraman.tif');
subplot(1, 2, 1);
imshow(grayImage);
grayImage = imadjust(grayImage, [130, 170]/255, [0, 255]/255);
subplot(1, 2, 2);
imshow(grayImage);