Received July 22, 2014, accepted August 9, 2014, date of publication August 18, 2014, date of current version August 27, 2014. Digital Object Identifier 10.1109/ACCESS.2014.2348943 Algorithms for Smartphone and Tablet Image Analysis for Healthcare Applications PAUL J. F. WHITE 1 , (Student Member, IEEE), BLAKE W. PODAIMA 1 , (Member, IEEE), AND MARCIA R. FRIESEN 2 1 Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada 2 Department of Design Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada Corresponding author: M. R. Friesen (marcia.friesen@umanitoba.ca) This work was supported by the Natural Sciences and Engineering Research Council of Canada under Grant 448147-2013. ABSTRACT Smartphones and tablets are finding their way into healthcare delivery to the extent that mobile health (mHealth) has become an identifiable field within eHealth. In prior work, a mobile app to document chronic wounds and wound care, specifically pressure ulcers (bedsores) was developed for Android smartphones and tablets. One feature of the mobile app allowed users to take images of the wound using the smartphone or tablet’s integrated camera. In a user trial with nurses at a personal care home, this feature emerged as a key benefit of the mobile app. This paper developed image analysis algorithms that facilitate noncontact measurements of irregularly shaped images (e.g., wounds), where the image is taken with a sole smartphone or tablet camera. The image analysis relies on the sensors integrated in the smartphone or tablet with no auxiliary or add-on instrumentation on the device. Three approaches to image analysis were developed and evaluated: 1) computing depth using autofocus data; 2) a custom sensor fusion of inertial sensors and feature tracking in a video stream; and 3) a custom pinch/zoom approach. The pinch/zoom approach demonstrated the strongest potential and thus developed into a fully functional prototype complete with a measurement mechanism. While image analysis is a very well developed field, this paper contributes to image analysis applications and implementation in mHealth, specifically for wound care. INDEX TERMS Algorithms, image analysis, smartphones, wound care. I. INTRODUCTION AND OBJECTIVE Smartphones and tablets are finding their way into healthcare delivery to the extent that mobile health, or mHealth, has become an identifiable field in eHealth. mHealth refers to the practice of medicine and public health supported by mobile devices, with an extensive range of applications ranging from apps that allow users to track their own diet and fitness, to devices and associated apps that allow for health condition monitoring and recording on a smartphone (e.g. blood sugar), to the use of mobile devices by nurses, physicians, and allied health professionals in direct healthcare delivery and medical record maintenance. In prior work, a mobile app to document chronic wounds and wound care, specifically pressure ulcers (bedsores) was developed for Android smartphones and tablets. This mobile app allowed users to take images of the wound using the smartphone or tablet’s integrated camera. In a user trial with nurses at a personal care home, this feature emerged as a key benefit of the mobile app [1]. Following on this finding, the current work had the objec- tive to develop image analysis algorithms that facilitate non-contact measurements of irregularly-shaped images taken with a sole smartphone or tablet camera, using only the sensors integrated in the smartphone or tablet with no auxiliary or add-on instrumentation on the device, and where the measurements have less than 10% error, for images taken from distances of up to 30 centimeters. II. BACKGROUND A. WOUND CARE MOBILE APP DESIGN AND USER TRIAL Pressure ulcers, also known as bedsores or decubitus ulcers, are a common but preventable condition seen most often in elderly persons and people with limited mobility. Pressure ulcer incidence rates vary widely from healthcare facility to facility, but the Canadian Association of Wound Care reports that one in four people in any healthcare facility have a pressure ulcer at any given time [2], [3]. Pressure ulcers are a disabling condition with numerous impacts on patient health and quality of life. Since they are often a secondary condition that develops upon admission to hospital, pressure ulcers can lengthen hospital stay, delay the recovery of the patient, and exacerbate mobility limitations and social isolation [4]. VOLUME 2, 2014 2169-3536  2014 IEEE. Translations and content mining are permitted for academic research only. Personal use is also permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. 831