Submitted version of the thesis - Airlab, the Artificial Intelligence ...

62 Chapter 5. Vision
background is much darker than the subject, or when photographing very
dark objects, such as black china on a black tablecloth.
From the parameters available in our camera we disabled the automatic
exposure by setting DIRECT MANUAL MODE, in which the exposure parameters
are input directly and not calculated by the camera. We don’t
want the camera automatically adjust the exposure, since this will cause to
lighten or darken the picture dynamically. Instead by setting the exposure
directly to a constant value, we ensure that the picture will remain with the
same enlightenment, together with the target we are searching for.
After setting the white balance and exposure compensation, we took
sample images (Figure 5.4) in order to define selected object’s color using
the script.
Figure 5.4: Samples are taken from different lighting conditions and different distance
to the target object
After acquiring the samples, the next step is creation of the histogram,
to find the distribution of the RGB values in the target object’s color. The
histogram created is shown in Figure 5.5.
An image histogram is a type of histogram that acts as a graphical representation
of the color distribution in a digital image. It plots the number of
pixels for each color value. By looking at the histogram for a specific image,