Fig 1.
Two rulers placed above and below the wound at approximately equal distances (d) from the wound edges.
There are 2 line segments (denoted as A and B) of the same length in cm drawn at the upper and the lower ruler which are used in wound area measurement for linear distance calibration.
Fig 2.
Relative differences between the measured area and reference area expressed in percentage for the digital planimetry based on photographs taken by 3 types of digital cameras in 3 positions of ruler: below the wound shape, above the wound shape, and with 2 rulers placed below and above.
Vertical bars denote 95% confidence intervals.
Table 1.
Standard deviations and ranges of relative differences between measured area and true area for three camera types and ratios of mean SDs for one ruler techniques and two ruler technique.
N denotes number of measurements.
Fig 3.
Box plot of relative errors of area measurement expressed in percentage for the digital planimetry based on one ruler or two ruler calibration techniques.
Fig 4.
Box-plot of relative errors of area measurement expressed in percentage for the digital planimetry method based on 2 rulers for 3 camera types: D-SLR, Compact, and Smartphone.
An asterix denotes statistically significant difference between the medians.
Fig 5.
Box plots of relative differences between the measured area and reference area expressed in percentage for the Visitrak device, the Silhouette Mobile device, the AreaMe software and for the digital planimetry methods based on two ruler calibration in 4 ranges of wound area: (A) very small (< 1 cm²), (B) small (1–2 cm²), (C) medium (2–8 cm²), and (D) large (> 8 cm²).
Fig 6.
Box plot of relative errors expressed in percentage for the digital planimetry methods (based on one and two ruler calibration) and for the Visitrak device, the Silhouette Mobile device and the AreaMe software.
The differences between medians are significant with p < 0.0001.