Error in imagesc matlab

Error using image
Color data must be numeric or logical values.

Error in imagesc (line 19)
    hh = image(varargin{1},'CDataMapping','scaled');

Error in file2>embedding_radiobutton_Callback (line 203)
imagesc(stegoimage);

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in file2 (line 17)
gui_mainfcn(gui_State, varargin{:});

Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)file2('embedding_radiobutton_Callback',hObject,eventdata,guidata(hObject)) 
Error while evaluating UIControl Callback.

[Walter Roberson]

If you put a breakpoint in embedding_radiobutton_Callback then what shows up for class(stegoimage)?

I speculate that it might be a character vector that is the name of a file rather than being the content of the file.