Real-time feature extraction from video stream data for stream ...

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Real-time feature extraction from video stream data for stream ...

6. Feature Extraction

personal computer, which is specified in more detail in the following chapter 7.

Image Transformation processors

When operating with the RapidMiner IMMI, it has turned out to be necessary to transform

images. Hence I have developed a set of image transformation processors.

The BorderDetection processor performs a border detection on the input image. A

pixel is said to be a border pixel, if its’ color differs from the color of at least one of

its’ four neighboring pixels significantly. By increasing the tolerance, the amount

of neighboring pixels that have to have the same color value can be decreased.

The ColorDiscretization processor discretizes the color space of the input image by

discretizing each single RGB color channel.

The ColorToGrayscale processor converts a color image to a grayscale image.

The Crop processor crops an image to a new size by cutting away parts of the image.

The DiffImage processor computes the difference image of the actual image and the

image before.

The Smoothing processor is a filter, smoothing the image. Hence the processor reduces

the noise in an input image. Each pixel gets replaced by the average of pixels in a

square window surrounding the pixel.

Image Feature Extraction processors

The AverageRGB processor extracts RGB colors from a given image and computes

the average RGB values over all pixels of that image.

The CenterOfMass processor calculates the Center of Mass of one color channel of

the image. You can either ask for the absolute x- and y-coordinates of the Center

of Mass or the normalized Center of Mass (= absolute Center of Mass / the size

of the image).

The ColorHistogram processor computes a color histogram on one color channel of

an image.

The MedianRGB processor extracts RGB colors from a given image and computes

the median value for each color channel.

The StandardDeviationRGB processor computes the standard deviation for all three

RGB channels. Requires the Average (=Mean) value for all RGB channels to be

included already. This can for example be done by using the AverageRGB processor.

Further processors

Beside the above mentioned processors, I have implement further processors, which were

necessary to run the experiments. A list of all processors is included in the appendix.

70

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