Cindy SongSharena Paripatyadar

• Use vision for HCI • Determine steps necessary to

incorporate vision in HCI applications• Examine concerns & implications of

such applications

Background and TrendsBackground and Trends In Today’s world:

• Many devices with integrated cameras• Many personal webcams

Our Goal:• To understand how to take advantage of

these one camera systems

Freeman and Roth For hand posture

analysis Creates histograms

of local orientation using feature vectors from pixel intensity

Recognizes 10 gestures in real time

Triesch and von der Malsburg

Based on Elastic Graph Matching

Extended for skin color feature detection

Recognizes 12 gestures

Freeman Uses one open

hand to control onscreen display

Real time application

Hand may not be prominent in image

5 participants, various technical backgrounds, age 20-27

Using computer with remote control Used alternate monitor to show user

video captured

Small set of user-intuitive gestures are easy to remember, but need some menu reminder

Show rationale behind gestures Visual feedback to show recognized

command before execution Concerns with:

Low-light conditionCamera field of view Webcam configurationResponsivenessAccuracy

ProsDon’t have to search for remoteDon’t have to touch remote while eatingNo battery to run down

ConsDoesn’t have as many features as remoteDoesn’t work in dark environmentsMore ambiguous than remote, more errors

possible – know what each button will do

Skin Color Training• Trained on 20+ images • Different lighting & people• Uses “Lab” color space

Calibration• Short training based on person’s hand and

lighting conditions - < 1 sec needed• Determines correct lighting & with skin color

data• Learns specific hand features

Hand Location• Determines hand position in image using

skin color• Fill in missing portions of hand • Create bounding box

Finger Region Detection• Examine bounding box• Find connected regions• Remove small regions

Pattern Recognition• Created set patterns based on 10

gestures• Counts number of finger regions for

gestures 1-5• For gestures 6-10, based on number

regions detected, looks at other patterns i.e. for 6 determine ratio of finger width to

space between fingers

Gesture Determination• 20 frames needed to recognize the gesture• Avoids recognizing accidental gestures

Complex Backgrounds • First skin color analysis• Then find large connected regions of fingers

and hand

Motion • Static gestures & frame by frame analysis• Allow for moving camera• Gesture determination corrects obscurities

or out of frame hand positioning

5 participants, various technical backgrounds, age 20-27

Taught users 2-4 gestures Quizzed users on gestures learned Ran gesture recognition algorithm to

provide feedback Asked several follow up questions

Useful for learning sign language, teaching kids to count

Instant feedback necessary Nice to know how to correct gesture Needs high accuracy Other applications

• Some said Media Player application more useful

• Or use as security system (hand gestures as a password)

Of implementationReal time is difficultPattern recognition for specific gestures vs.

technique for all types of gesturesComplex/moving backgrounds important for

real world applications

Of user studiesVideo is valuable avenue for many applicationsAccuracy and responsiveness are importantIn one camera systems, there is a tradeoff

between convenience and clarity

Real-time More user studies Mobile devices Gesture learning

application• i.e. Chinese cultural gestures

Media Player plug-in application