java - input Mat used in goodFeatureToTrack -
i'm trying detect feature in face goodfeaturetotrack function in java. crashes there. code:
mat eyeregion = detectcascade();//i used here cascadeclassifier detect eye region if(eyeregion.empty())     log.i("face_calibrated","eye region empty"); i make sure region not empty.
if(eyeregion.channels()==1)  {   //i convert mat rgb detectfeatures     imgproc.cvtcolor(eyeregion, eyeregion, imgproc.color_gray2rgb);     log.i("face_calibrated","eyeregion channel1"); } here problem:
imgproc.goodfeaturestotrack(eyeregion,cornersa,4,0.01,5.0,null,3,false,0.04); i have declared cornersa global matofpoint 
public matofpoint cornersa = new matofpoint(); what type of input mat (rgb or gray) should used in function?