Well it's a little bit tricky to detect the most common types of images: grayscale, RGB, and indexed . Of course your "binary image" is most likely a grayscale uint8 image with gray levels of only 0 and either 1 or 25. See this snippet which handles all of those, and adapt as needed:
%=====================================================================
% Reads FullImageFileName from disk into the axesImage axes.
function imageArray = DisplayImage(handles, fullImageFileName)
% Read in image.
imageArray = []; % Initialize
try
[imageArray, colorMap] = imread(fullImageFileName);
% colorMap will have something for an indexed image (gray scale image with a stored colormap).
% colorMap will be empty for a true color RGB image or a monochrome gray scale image.
catch ME
% Will get here if imread() fails, like if the file is not an image file but a text file or Excel workbook or something.
errorMessage = sprintf('Error in program %s, function %s(), at line %d.\n\nError Message:\n%s', ...
mfilename, ME.stack(1).name, ME.stack(1).line, ME.message);
uiwait(warndlg(errorMessage));
return; % Skip the rest of this function
end
try
% Display image array in a window on the user interface.
%axes(handles.axesImage);
hold off; % IMPORTANT NOTE: hold needs to be off in order for the "fit" feature to work correctly.
% Here we actually display the image in the "axesImage" axes.
imshow(imageArray, 'InitialMagnification', 'fit', 'parent', handles.axesImage);
% Display a title above the image.
[folder, basefilename, extension] = fileparts(fullImageFileName);
extension = lower(extension);
% Display the title.
caption = [basefilename, extension];
title(handles.axesImage, caption, 'Interpreter', 'none', 'FontSize', 14);
[rows, columns, numberOfColorChannels] = size(imageArray);
% Get the file date
fileInfo = dir(fullImageFileName);
txtInfo = sprintf('%s\n\n%d lines (rows) vertically\n%d columns across\n%d color channels\n', ...
[basefilename extension], rows, columns, numberOfColorChannels);
% Tell user the type of image it is.
if numberOfColorChannels == 3
colorbar 'off'; % get rid of colorbar.
txtInfo = sprintf('%s\nThis is a true color, RGB image.', txtInfo);
elseif numberOfColorChannels == 1 && isempty(colorMap)
colorbar 'off'; % get rid of colorbar.
txtInfo = sprintf('%s\nThis is a gray scale image, with no stored color map.', txtInfo);
elseif numberOfColorChannels == 1 && ~isempty(colorMap)
txtInfo = sprintf('%s\nThis is an indexed image. It has one "value" channel with a stored color map that is used to pseudocolor it.', txtInfo);
colormap(colorMap);
whos colorMap;
%fprintf('About to apply the colormap...\n');
% Thanks to Jeff Mather at the Mathworks to helping to get this working for an indexed image.
colorbar('peer', handles.axesImage);
%fprintf('Done applying the colormap.\n');
end
catch ME
errorMessage = sprintf('Error in program %s, function %s(), at line %d.\n\nError Message:\n%s', ...
mfilename, ME.stack(1).name, ME.stack(1).line, ME.message);
uiwait(warngld(errorMessage));
end
uiwait(helpdlg(txtInfo));
return; % from DisplayImage
