roipoly help - colours display badly (so unable to define)

I have a 1660 x 986 matrix with values up to 2500 (it represents a digital elevation model).

I need to define an area using roipoly but when it displays in roipoly, the colour bar only goes up to 1, so the whole image is white apart from one small spot near 0.

In case this is relevant, it does tell me:

Warning: Image is too big to fit on screen; displaying at 33% > In imuitools/private/initSize at 73 In imshow at 262 In roipoly>parse_inputs at 191 In roipoly at 81

Is there a way to solve this?! Thank you

Answer 1

[Walter Roberson]

What is class() of the data? With that range of values, if it is not int16 or uint16 then it is not an "image" as is required for input to roipoly()

Answer 2

[Image Analyst]

Try roipolyold() instead of roipoly. You don't have the extra step of having to confirm your vertex points and it gives you an alternating black and white dashed line that you can see over almost any image.

To turn off the warning, see this:

% Turn off this warning "Warning: Image is too big to fit on screen; displaying at 33% "
% To set the warning state, you must first know the message identifier for the one warning you want to enable. 
% Right after your line of code generates the error,
% query the last warning to discover the warning identifier.  For example: 
% warnStruct = warning('query', 'last');
% messageID = warnStruct.identifier
% In the command window, this will show:
% messageID =
%    MATLAB:concatenation:integerInteraction
% Pass that into the warning function:
warning('off', 'Images:initSize:adjustingMag');