Accuracy of food portion size estimation from digital pictures acquired by a chest-worn camera.
OBJECTIVE
Accurate estimation of food portion size is of paramount importance in dietary studies. We have developed a small, chest-worn electronic device called eButton which automatically takes pictures of consumed foods for objective dietary assessment. From the acquired pictures, the food portion size can be calculated semi-automatically with the help of computer software. The aim of the present study is to evaluate the accuracy of the calculated food portion size (volumes) from eButton pictures.


METHODS
Participants wore an eButton during their lunch. The volume of food in each eButton picture was calculated using software. For comparison, three raters estimated the food volume by viewing the same picture. The actual volume was determined by physical measurement using seed displacement.


METHODS
Dining room and offices in a research laboratory.


METHODS
Seven lab member volunteers.


RESULTS
Images of 100 food samples (fifty Western and fifty Asian foods) were collected and each food volume was estimated from these images using software. The mean relative error between the estimated volume and the actual volume over all the samples was -2·8 % (95 % CI -6·8 %, 1·2 %) with sd of 20·4 %. For eighty-five samples, the food volumes determined by computer differed by no more than 30 % from the results of actual physical measurements. When the volume estimates by the computer and raters were compared, the computer estimates showed much less bias and variability.


CONCLUSIONS
From the same eButton pictures, the computer-based method provides more objective and accurate estimates of food volume than the visual estimation method.
1Department of Neurosurgery,University of Pittsburgh,Pittsburgh,PA 15213,USA.
Wenyan
W
Jia
1Department of Neurosurgery,University of Pittsburgh,Pittsburgh,PA 15213,USA.
Hsin-Chen
HC
Chen
2Department of Electrical and Computer Engineering,University of Pittsburgh,Pittsburgh,PA,USA.
Yaofeng
Y
Yue
1Department of Neurosurgery,University of Pittsburgh,Pittsburgh,PA 15213,USA.
Zhaoxin
Z
Li
4Department of Psychiatry,University of Pittsburgh,Pittsburgh,PA,USA.
John
J
Fernstrom
2Department of Electrical and Computer Engineering,University of Pittsburgh,Pittsburgh,PA,USA.
Yicheng
Y
Bai
2Department of Electrical and Computer Engineering,University of Pittsburgh,Pittsburgh,PA,USA.
Chengliu
C
Li
1Department of Neurosurgery,University of Pittsburgh,Pittsburgh,PA 15213,USA.
Mingui
M
Sun
D000328:Adult; D004034:Diet Surveys; D002149:Energy Intake; D005260:Female; D005502:Food; D006801:Humans; D062409:Lunch; D008297:Male; D010781:Photography; D064787:Portion Size; D012044:Regression Analysis; D015203:Reproducibility of Results; D012858:Size Perception; D013909:Thorax