detectSURFFeatures shows error.

Im Using Matlab 2013a version and having a problem when using command:

boxPoints = detectSURFFeatures(boxImage);

Got error

Error using detectSURFFeatures
Expected input number 1, I, to be two-dimensional.

Error in detectSURFFeatures>parseInputs (line 82)
validateattributes(I,{'logical','uint8', 'int16', 'uint16', ...

Error in detectSURFFeatures (line 71)
[Iu8 params] = parseInputs(I,varargin{:});

As I am beginner and trying to use Matlab for Image processing and seeking help from the example available on the following link: http://www.mathworks.com/help/vision/examples/object-detection-in-a-cluttered-scene-using-point-feature-matching.html#btt5qyu

[Sehar Un Nisa]

I am having same error with greyscale image

Error in detectSURFFeatures (line 71) [Iu8 params] = parseInputs(I,varargin{:});

[Walter Roberson]

Please show size() of the image.

It is possible for an image to look gray but actually be an RGB image. If the Red, Green, and Blue color planes are identical at each pixel, then the image will be an RGB image with gray content.

[Mohamed Inamul Hasan A]

tq dude.... It works

Answer 1

[Steven Lord]

The documentation for detectSURFFeatures states, in part (emphasis added):

"POINTS = detectSURFFeatures(I) returns a SURFPoints object, POINTS, containing information about SURF features detected in the 2-D grayscale input image I."

This indicates that it does not accept RGB images, which would be 3-D (rows-by-pages-by-3 for the 3 color pages.) Convert your image to grayscale before passing it into detectSURFFeatures.

[M.Farhan Khan]

Thank you Mr Steven.