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Pediatric measurement device for early detection of plagiocephaly iPhone App Edition. Cody Hall Chris Heelan Jorge Perez. Craniometer. Project goal To develop a low cost, safe, and accurate plagiocephaly measurement device for children aged infant to 24 months
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Pediatric measurement device for early detection of plagiocephalyiPhone App Edition Cody Hall Chris Heelan Jorge Perez
Craniometer • Project goal • To develop a low cost, safe, and accurate plagiocephaly measurement device for children aged infant to 24 months • Digital solution that limits complexity as to lower price • Initial design • Physical Device • Two digitial calipers used to detect linear distances and angles
Craniometer Pros/Cons Pros Cons Hardware design PCB design/debugging Component selection Mechanical design AutoCAD parts Purchasing physical parts Assembling physical parts Requires physical contact with the infant Third-party required for manufacturing/marketing • Simple Theory • Directly sense angle using sensor • Calculate distances using trigonometry • Simple UI • Three push buttons • Results clearly displayed on LCD • Easier to use with squirming child • Simple design • Increased reliability • Requires small investment by pediatrician
iPhone Application • New design • iPhone application • Use camera to take image of infant’s head • Markers on paper provide absolute distance calibration • PDF included with app • Perform image analysis to calculate angles/linear distances • Display results on phone
iPhone Application Pros/Cons Pros Cons More complex theory Calibrate pixels to distance using known markers in image Edge-detection processing to calculate linear distances Requires pediatrician to own iPhone More complicated UI Also more complicated to design Harder to use with squirming child Camera must be parallel to child’s head Requires designers to learn Cocoa (Objective-C) programming • User already owns physical device • No hardware to manufacture/purchase • Safer • No physical contact with child • App Store provides simple distribution method • Focus on purely software will allow for a more polished and professional product • Potential Market • Estimated 58,000 pediatricians in the United Stated (American Academy of Pediatrics) • 94% of doctors own smartphones (compared to 59% in 2006) • Doctors prefer iPhone (44%) to Blackberry (25%) and Andriod (25%) • Estimated 24,000 potential customers • Verizon adding iPhone this year
How do we know this will work? • iPhone 4 Camera Specifications • Back- Illuminated CMOS Sensor • 5-Megapixel Resolution (2592 x 1936) • Fixed aperture f/2.8 • Permanent 3.85mm focal length
iPhone Camera Testing • Third party research • <0.2% barrel distortion = Very Good • Low noise • <2% under fluorescent lighting (ISO 144) • Need to determine sharpness • Rise distance
Resolution • 30cm x 22cm area / 2592 x 1936 pixels • Gives us a 0.13mm spatial resolution under perfect conditions
Segmentation and Edge Detection • Use of histogram threshold
Connected Component Labeling Necessary labeling method to mark different circles
Find the centers of circles- strike a chord Find the maximum distance from one point on the edge to another Take midpoint as center Distance between centers is determines pixel size
Challenges • Developing efficient algorithms to work on iPhone • Automated or assisted point selection process- GUI control • Maintaining millimeter resolution during heavy image processing
iPhone App Development • Required Computer running Mac OS -two designers own OSX machines Register with Apple as a developer -two designers registered Download/install SDK -two designers have successfully installed/used the SDK Create application Submit application to App Store for approval
Application Programming • Learning Cocoa (Objective-C) • Stanford iPhone app development lectures • Free from iTunes University • Full semester course (lecture videos and PPT slides) • Other online coding/app tutorials • One team member proficient in C programming • Layer underneath Objective-C • One team member proficient in Java programming • Object-oriented programming
Image Processing Algorithms • ImageJ • Free image processing program • Open source Java code • Port needed algorithms to Objective-C • One designer proficient in Java • Independent research • Image processing tutorials online in many different coding languages
Image Processing Location • Two choices for image processing • All processing written within application (Objective-C) • App is completely localized • Processing performed on server running Python script • App captures/displays image and provides GUI • App sends image to server • Image processing offloaded to Python • Script sends results back to app