Why do I receive an error when using HIST with integer data types?

The HIST function does not appear to work with integer data types in MATLAB 7.2 (R2006a). I enter the following code at the MATLAB Command Prompt:

y = uint8(10*rand(1000,1));

hist(y)

I receive the error message:

 ??? Error using ==> mtimes

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

 Error in ==> hist at 73

         xx = miny + binwidth*(0:x);

I would like to create a histogram from UINT8, UINT16, and UINT32 data.

Answer 1

[MathWorks Support Team]

This change has been incorporated into the documentation in Release 2009b (R2009b). For previous releases, read below for any additional information:

This is expected behavior for the HIST function in MATLAB. It is designed to work with single and double data types. You may instead wish to use the function IMHIST in Image Processing Toolbox which can handle a larger range of integer data types.

To create a histogram in MATLAB from integer data with HIST, you will need to manually specify integer bin centers. For example,

y = uint8(10*rand(1000,1));

hist(y,0:10)

You may also typecast your integer data using the DOUBLE function:

hist(double(y));

Note that if you typecast, the bin centers will not always be integers; this may distort your data.