3.4.2. Components of the Scanning Device

A digital camera with resolution of 640 × 480 pixels and 8 bits was used for image scanning. This suggests the realization of grey-toned images, with 255 shades of grey. Firewire interface was used to transfer stored data from the camera. A stable focal distance of 4.5 mm from the manufacturing class VCN was used. The IR filter plays the important role of scanning the IR part of the spectrum [63–65]. This was needed since sunlight impact on the scanned image is a limitation. Another part of the scanning device is the source of IR radiation. Therefore, tests with different sources of IR radiation were conducted. The lighting tests include: direct circular lighting, direct linion lighting, diffused DOM lighting, and background lighting. On the basis of the test results, the most suitable lighting, DOM, was selected. This lighting uses LED lights with the wavelength of 850 nm and allows for generation of images with homogenous lighting, with a well recognizable structure of veins on the top of the hand, as well as a sufficient contrast of the hand against the background. This is good for further evaluation of the hand contour.

Lights and the camera configuration was put on the construction from aluminum profiles, which was mounted on an adjustable tripod (based on the configuration). The background comprises of a black matte surface that helps to get the contrast between the background and the scanned image of the user hand. The whole configuration of the camera, optics, and the lighting is displayed on the images in Figures 10 and 11. From these estimates, the average cost of the scanner is about €1490, which is relatively expensive. Nonetheless, selected sellers/manufacturers are the most revered in terms of sales of most durable spares, which is why the prices are so high. The components may be purchased from other sellers at cheaper rates, which will most likely reduce the average possible cost of the proposed scanner [66].

**Figure 10.** Configuration of the camera and lighting.

**Figure 11.** Configuration of the camera and lighting.

**Figure 12.** Possible types of lighting within the scene.
