Measurement Guide

1. What is calibration?

Calibration is essential for the DermoPico Skin APP to function. Since our CMA Skin devices are used with various types of cellphones and distinct models of cellphone possess different camera modules, selecting the exact region-of-interest (ROI) from the images taken by different cellphones is key to accurate skin diagnosis. Our DermoPico Skin calibration procedure is designed just to achieve this.

With calibration we obtain a key parameter “size-factor“. By storing this size-factor in APP, each time when a skin image is captured we are able to get from the image the exact ROI for diagnosis.

To perform calibration, make sure you have the CMA Skin device correctly attached to your cellphone allowing ideal alignment of the camera lens and the CMA Skin device peephole. We begin calibration by capturing an image of the calibration paper. Do ensure you are using the high-quality calibration paper that comes with the CMA Skin device. Using any self-printed calibration paper will affect the calibration and diagnoses results.

Figure 1

Figure 1. Calibration paper for DermoPico Skin application

2. Calibration for DermoPico Skin

We begin calibration by capturing an image of the calibration paper. The only requirement when taking the image is to make sure the middle red dot is at the center of the field-of-view (FoV), or say at the center of the peephole of the CMA Skin device. Well captured DermoPico Skin calibration images are as follows.

Figure 2-1-1Figure 2-1-2

Figure 2-1. Well captured DermoPico Hair calibration images (Gen2)

Figure 2-2-1Figure 2-2-2

Figure 2-2. Well captured DermoPico Hair calibration images (Gen1)

To ensure calibrations are done correctly, we can check the result images given by our calibration algorithm. The following images demonstrate examples of nicely done skin calibrations from which we can see a green circle and a red rectangle are drawn around the middle red dot without overlapping with any device parts.

Figure 3-1-1Figure 3-1-2

Figure 3-1. Example results of correctly done DermoPico Skin calibrations (Gen2)

Figure 3-2-1Figure 3-2-2

Figure 3-2. Example results of correctly done DermoPico Skin calibrations (Gen1)

The following table shows example skin ROI images after calibration with different mobile devices using both Gen1 and Gen2 CMA skin devices.

Table 1. Example skin ROI images after calibration
Cellphone ModelOriginal ImageROI Image
Galaxy S9, CMA Skin Gen1ImageImage
Galaxy S9, CMA Skin Gen2ImageImage
iPhone 6s, CMA Skin Gen1ImageImage
iPhone 6s, CMA Skin Gen2ImageImage
iPhone 11 Pro, CMA Skin Gen2ImageImage

3. When calibration is necessary

The table below summarizes the criteria when calibration is necessary in the DermoPico Skin APP:

  • Initial use of the DermoPico Skin APP and the CMA Skin device
  • Upon removal and reinstallation of the DermoPico Skin APP
  • Upon full detachment and reattachment of the CMA Skin device and the holder
  • When you notice diagnoses result images come out with parts of the CMA Skin device in it. This could happen if after previous successful calibration, the CMA Skin device holder has shifted position