Comparison of different clothing area factor (fcl) calculations based on picture analysis in Adobe Photoshop: To calculate the intrinsic insulation (Icl)

Introduction: Clothing area factor (fcl) is an indicator of the increase in surface area relative to the nude body for calculation of heat loss from the clothed body to the environment. The aim was to calculate and compare the fcl values from two equations by the photographic method.

Method: Thirty-five modern western indoor clothing sets (19 male and 16 female) were tested on a thermal manikin Tore. In order to calculate fcl , front and side views of nude and dressed manikin were photographed against bright background. During analysis in Adobe Photoshop, colour information was discarded by selecting Grey scale mode. Then Curve was adjusted under Image to increase the manikin contrast against the background. The surrounding objects were eliminated by selecting black manikin silhouette, inversing the selection and deleting background residues. In the Histogram, Brightness and Contrast were adjusted to minimum and maximum levels, respectively. Then the black silhouette was selected with Magic wand tool and pixel number was recorded followed by deselecting the whole picture, percentile of pixels was taken, when cursor was left at level 100. The fcl-s were calculated based on both pixels and percentile by two equations and the comparison was made:
f_cl=(〖Front〗_clothed+〖Side〗_clothed)/(〖Front〗_nude+〖Side〗_nude )
f_cl=(〖Front〗_clothed/〖Front〗_nude +〖Side〗_clothed/〖Side〗_nude )/2

Results: The calculated fcl means (SDs) for Eq. 1 found similar for both pixels and percentile 1.17 (0.07), while those values for Eq. 2 appeared 1.19 (0.07) and 1.18 (0.07), respectively. The fcl means (SDs) differences equation wise for pixels and percentiles were 1.04 (0.57) % and 1.09 (0.57) %, respectively. The calculated basic means (SDs) insulation (Icl) did not differ when using the respective pixels and percentile fcl values.

Conclusions: Two equations provided the fcl values with a small difference based on either pixels or percentile of picture and did not affect the calculated intrinsic clothing insulation, Icl.