how to rectify this error

Error using imhist Expected input number 1, I or X, to be two-dimensional.

Error in imhist>parse_inputs (line 277) validateattributes(a, {'double','uint8','int8','logical','uint16','int16','single','uint32', 'int32'}, ...

Error in imhist (line 59) [a, n, isScaled, top, map] = parse_inputs(varargin{:});

Error in mainnnn (line 7) [p,x]=imhist(J,256);

Answer 1

[Walter Roberson]

You probably used imread() to read in an image, and the image is stored as a 3 dimensional matrix because it is an RGB (truecolor) image. imhist() can only be applied to 2D images such as grayscale images.