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250 Bu il d Y o ur O w n Q u a d c o p t e r

Figure 9.28 Live video filtered by a Canny edge algorithm.

Fourteen different edge filter selections appear when the + symbol is clicked on the
Edges content selection. Other content selections will have multiple selections associated
with them. At first glance, this would appear to be a bit overwhelming with so many different
selections; however, you will likely use only a few to achieve what you want. The RoboRealm
designers created a highly capable image-processing system that meets many different user
needs. Incidentally, the Canny Edge Detector will be explained in greater detail later in
this section.
An inherent problem with processing live video is that the original image is constantly
changing, which makes it difficult to assess what the effect of multiple filter operations on
an image will be. That is why I strongly recommend that you take a snapshot of the video
and apply the processing to that image. In that way, you not only retain the original image,
but you can also save separate images of all the processed images. To take a snapshot, simply
click on the Snap button located on the bottom menu bar, and enter a name for the snapshot
when prompted.
Figure 9.29 is a snapshot of my Elev-8 that I captured from a video taken with the RC310
camera. I will use this snapshot as the raw image to demonstrate a few of the image-
processing algorithms.

The Histogram
The first processing effect I will show is the histogram, which is probably the algorithm that
will be familiar to most readers. Many DSLRs have histogram displays to help photographers
determine if their photos are properly exposed. The display is a small graph of vertical lines
that show the distribution of all the red, green, and blue (RGB) pixel intensities contained