# Image Quality Assessment of Digital Image Capturing Devices for Melanoma Detection
## 3 Results
### Results of Colour Measurements
#### 3.2.2 Colours in the Dermoscopy Image  
Dermoscopy images were captured through the DermLite 4 DL handheld dermoscope attached to a smartphone or digital camera lens. Image colour analysis was performed on a set of six skin-colour patches from the X-Rite test chart. Due to the small dimension of the dermoscope viewing field (approximately 20 mm in diameter), each colour patch was captured and measured separately. In Figure 9, colours and their differences concerning reference colours for auto mode camera setting from dermoscopy captured images are presented on the map in two layers: the captured colour is in the foreground, and the reference colour is in the background. The resulting impression on the dermoscopy captured images indicates that the images are generally overexposed, and, in general, the \(\Delta E\) colour difference response is relatively high as compared to the reference values. The \(\Delta E\) colour distance calculated from a captured image regarding the reference colour is shown in Table 5. The first column in Table 5 identifies the name of the device used. The second column lists the mean colour difference \(\Delta E_{mean}\) on six different tested colours. The third and fourth columns present the maximum \(\Delta E_{max}\) and minimum \(\Delta E_{min}\) difference values. The results in Table 5 show that the smallest \(\Delta E_{mean}\) = 15.0 distance was achieved evaluating images captured by the Huawei P10 camera, with the highest colour distance of \(\Delta E_{max}\) = 22.7. Therefore, our measuring revealed that low error responses were achieved when images were captured either by the iPhone XR or the Canon EOS M10 camera. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Camera** & **CT (K)** & \(\Delta E_{mean}\) & \(\Delta E_{min}\) & \(\Delta E_{max}\) \\ \hline iPhone 5s & 3200 & 20.2 & 1.3 & 42.3 \\  & 5500 & 27.3 & 3.4 & 66.9 \\ \hline iPhone 7 & 3200 & 14.1 & 3.6 & 33 \\  & 5500 & 39.6 & 22.1 & 69.5 \\ \hline iPhone XR & 3200 & 20.3 & 2.0 & 42.1 \\  & 5500 & 31.3 & 6.5 & 71.1 \\ \hline Samsung S10 & 3200 & 15.6 & 7.6 & 21.2 \\  & 5500 & 13.1 & 4.8 & 21.7 \\ \hline Huawei P10 & 3200 & 21.6 & 13.3 & 21.7 \\  & 5500 & 35.2 & 7.5 & 69.2 \\ \hline Canon EOS M10 & 3200 & 25.9 & 11.1 & 37.4 \\  & 5500 & 30.2 & 3.5 & 68.8 \\ \hline Canon EOS 800D & 3200 & 28.6 & 20.5 & 37.4 \\  & 5500 & 25.2 & 12.8 & 40.6 \\  & Flash & 7.4 & 3.4 & 12.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Colour accuracy is given with colour distances as mean value \(\Delta E_{mean}\), minimum \(\Delta E_{min}\) and maximum \(\Delta E_{max}\), calculated on 16 colours from the test chart. Figure 9: The colour presentation of dermoscopy images about reference colours for auto mode camera setting. The CIELAB \(\Delta E\) colour distance of skin tone colour patches are set forth. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Auto Mode**} & \multicolumn{3}{c}{**Manual Mode**} \\ \hline
**Camera** & \(\Delta E_{mean}\) & \(\Delta E_{min}\) & \(\Delta E_{max}\) & \(\Delta E_{mean}\) & \(\Delta E_{min}\) & \(\Delta E_{max}\) \\ \hline iPhone 5s & 32.1 & 15.4 & 43.1 & 9.7 & 6.4 & 12.8 \\ iPhone 7 & 31.0 & 12.5 & 62.7 & 9.1 & 5.2 & 11.7 \\ iPhone XR & 20.6 & 12.5 & 25.3 & 9.6 & 5.1 & 12.9 \\ Samsung S10 & 33.3 & 19.1 & 42.6 & 11.1 & 5.7 & 16.1 \\ Huawei P10 & 15.0 & 4.5 & 22.7 & 9.3 & 6.0 & 15.3 \\ Canon EOS M10 & 20.5 & 2.8 & 43.4 & 11.3 & 7.8 & 14.4 \\ Medicam 1000s & 45.7 & 26.2 & 64.7 & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Colour reproduction accuracy is given for auto and manual mode camera setting as mean \(\Delta E_{mean}\) colour distance, minimal \(\Delta E_{min}\) and maximal \(\Delta E_{max}\) value regarding the six skin tone reference colours.