Converting Image pixel range

Dear All, I have an image whose intensity values ranges from -15 to +20. I want to convert it to 8-bit and 16-bit values. Please let me know the algorithm/formula that I can use to program in matlab. In addition, how to save the image in 8-bit and 16 bit in matlab.

regards and thanks

Answer 1

[Image Analyst]

Try this:

image8 = uint8(mat2gray(yourDoubleImage) * intmax('uint8'));
imwrite(fullFileName, image8);
image16 = uint16(mat2gray(yourDoubleImage) * intmax('uint16'));
imwrite(fullFileName, image16);

[try analyst]

Thanks Image Analyst, Please let me know the conversion ranges from -15 to +20 to 0 to 255 and the code You added is giving error.

Error using * Integers can only be combined with integers of the same class, or scalar doubles.

Thanks in advance for your help.

[Image Analyst]

Try wrapping intmax in double

double(intmax('uint8'))

[try analyst]

Yes it works but the quality of the image is very bad.

[Guillaume]

im2uint8 and im2uint16 are simpler for doing the conversion from [0 1] to whichever range:

image8 = im2uint8(mat2gray(yourimage));
image16 = im2uint16(mat2gray(yourimage));

"the quality of the image is very bad"

If it's after saving the image, possibly it's because you're not using an appropriate image format.

If it's after the conversion to uint8 and uint16, then don't do the conversion! By definition, converting to integers is going to discretise your image. Although, with uint16 having 65536 levels of grey, it shouldn't be an issue.