Creating an image from values in the range [-1,1] and applying a colormap

Hello,

I have a matrix of data which I am trying to show as an image with values that range from -1 to 1. Ideally, I would like to keep these values within this range and not have to compress them to [0,1] but I am not sure if this is possible or how to best approach it.

Second, I would like to apply a colormap to this image that covers the entire -1 to 1 range but this would require the -1 to 1 image unless there is another way to do it. Any help with this would be appreciated!

Answer 1

[Walter Roberson]

data = rand(30,50) * 2 - 1;
imagesc( data, [-1 1]);
colormap( prisim(256) )

[Coby Allred]

Is there any way to export this image while keeping the -1 to 1 values? I don't believe that the ind2rgb would properly keep the -1 to 1 range if there is not data at these extremes.

[Image Analyst]

You can use save() to save it to a .mat file.

[Walter Roberson]

You can create floating point TIFF images; see https://www.mathworks.com/matlabcentral/answers/7184-how-can-i-write-32-bit-floating-point-tifs-with-nans

Note: floating point TIFF images are not common, and your viewer might not know how to deal with them.