Color Segmentation & Introduction to Motion Planning CSE350/ Sep 03

Administration Questions?

Class Objectives Review how color is represented and can be segmented in a computer image Introduction to basic Motion Planning for a mobile robot

Supporting References Color Segmentation –CVOnline “Color Image Processing” Lecture Notes –Poynton's Color FAQ Motion Planning –“Motion Planning Using Potential Fields”, R. Beard & T. McClain, BYU, 2003

Color Segmentation Motivation Computationally inexpensive (relative to other features) “Contrived” colors are easy to track Combines with other features for robust tracking

What is Color? Color is the perception of light in the visible region of the spectrum Wavelengths between 400nm - 700nm Imagers –Retina (humans) –CCD/CMOS (cameras)

RGB Color Space Motivated by human visual system –3 color receptor cells (rods) in the retina with different spectral response curves Used in color monitors and most video cameras

YCbCr (YUV/YIQ) Color Space “Greyscale” Y= 0.30*R+0.59*G+0.11*B Separates luma (“brightness”) from the chroma (“color”) channels: Y = 0.30*R+0.59*G+0.11*B, Cb = B-Y, Cr=R-Y YUV/YIQ are similar variants based upon NTSC/PAL television signals

Representing Colors in an RGB Image RedGreenBlue

How do we segment a “single” color? Sample set for orange hat

Simple RGB Color Segmentation && RedGreenBlue Segmented Color Image Again the Issue of Thresholding!

Color Tracking Demo

Motion Planning

The Basic Motion Planning Problem Given an initial robot position and orientation in a potentially cluttered workspace, how should the robot move in order to reach an objective pose?