Try this,
file_name = uigetfile('*.*');
imgInfo = imfinfo(file_name);
if strcmp(imgInfo.ColorType,'grayscale')
display('This is a gray scale image');
img = imread(file_name);
figure, imshow(img,[]), title('grayscale image');
elseif strcmp(imgInfo.ColorType,'truecolor')
errordlg('This is a true color image choose grayscale image');
elseif strcmp(imgInfo.ColorType,'indexed')
errordlg('This is a indexed image choose grayscale image');
else
errordlg('Incorrect file type choose grayscale image');
end
Let me know if this is what you want..
Good Luck
