Rescale 8-bit grayscale image

1. intensity values in the range [0..63] in f become 0,
2. in the range [63+1..126] are rescaled into the range [0..120],

How to rescale the image? Thanks.

Answer 1

[DGM]

Here's a start:

inpict = imread('cameraman.tif');

inrange = [64 126; 127 230];
outrange = [0 120; 151 255]; % you sure you don't mean 121?

m = inpict<=inrange(1,2);
outpict = zeros(size(inpict),'uint8');
outpict(m) = (double(inpict(m))-inrange(1,1))./(inrange(1,2)-inrange(1,1)) ...
	.*(outrange(1,2)-outrange(1,1))+outrange(1,1);
outpict(~m) = (double(inpict(~m))-inrange(2,1))./(inrange(2,2)-inrange(2,1)) ...
	.*(outrange(2,2)-outrange(2,1))+outrange(2,1);

imshow(outpict)

imhist(outpict)

You can do the same using interpolation:

inpict = imread('cameraman.tif');

inrange = [0 64 126 127 230 255];
outrange = [0 0 120 151 255 255];

outpict = uint8(interp1(inrange,outrange,double(inpict),'linear','extrap'));

imshow(outpict)

imhist(outpict)

[Ben Ma]

No, not 121, will skip that middle range

[Ben Ma]

Thanks a lot.