image feature extraction and matching

i need help,i want to do feature matching in matlab 2013a,but iam having this error "Error using harrisMinEigen Expected input number 1, I, to be two-dimensional.",i thought may be my two input image has to be 2D,I converted them in 2D first but i still have the same problem.I need to understand what is the meaning of this error and how to rectify it,here are the codes iam using I1 =imread('rgb1.jpg'); I2 =imread('rgb3.jpg'); %j2=cat(2,I2,I2); %Find the corners. points1 = detectHarrisFeatures(I1); points2 = detectHarrisFeatures(I2); %Extract the neighborhood features. [features1, valid_points1] = extractFeatures(I1, points1); [features2, valid_points2] = extractFeatures(I2, points2); %Match the features. indexPairs = matchFeatures(features1, features2); %Retrieve the locations of corresponding points for each %image. matched_points1 = valid_points1(indexPairs(:, 1), :); matched_points2 = valid_points2(indexPairs(:, 2), :); %Visualize corresponding points. You can see the effect %of translation between the two images despite several erroneous matches. figure; showMatchedFeatures(I1,I2, matched_points1, matched_points2);

Answer 1

[Haron Tinega]

convert the image from RGB to Gray then it can work