Motion Analysis and Object Tracking

Acc

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Acc(image, sum, mask=NULL) → None

Adds a frame to an accumulator.

Parameters:

• image (CvArr) – Input image, 1- or 3-channel, 8-bit or 32-bit floating point. (each channel of multi-channel image is processed independently)
• sum (CvArr) – Accumulator with the same number of channels as input image, 32-bit or 64-bit floating-point
• mask (CvArr) – Optional operation mask

The function adds the whole image image or its selected region to the accumulator sum :

MultiplyAcc

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MultiplyAcc(image1, image2, acc, mask=NULL) → None

Adds the product of two input images to the accumulator.

Parameters:

• image1 (CvArr) – First input image, 1- or 3-channel, 8-bit or 32-bit floating point (each channel of multi-channel image is processed independently)
• image2 (CvArr) – Second input image, the same format as the first one
• acc (CvArr) – Accumulator with the same number of channels as input images, 32-bit or 64-bit floating-point
• mask (CvArr) – Optional operation mask

The function adds the product of 2 images or their selected regions to the accumulator acc :

RunningAvg

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RunningAvg(image, acc, alpha, mask=NULL) → None

Updates the running average.

Parameters:

• image (CvArr) – Input image, 1- or 3-channel, 8-bit or 32-bit floating point (each channel of multi-channel image is processed independently)
• acc (CvArr) – Accumulator with the same number of channels as input image, 32-bit or 64-bit floating-point
• alpha (float) – Weight of input image
• mask (CvArr) – Optional operation mask

The function calculates the weighted sum of the input image image and the accumulator acc so that acc becomes a running average of frame sequence:

where regulates the update speed (how fast the accumulator forgets about previous frames).

SquareAcc

Comments from the Wiki

SquareAcc(image, sqsum, mask=NULL) → None

Adds the square of the source image to the accumulator.

Parameters:

• image (CvArr) – Input image, 1- or 3-channel, 8-bit or 32-bit floating point (each channel of multi-channel image is processed independently)
• sqsum (CvArr) – Accumulator with the same number of channels as input image, 32-bit or 64-bit floating-point
• mask (CvArr) – Optional operation mask

The function adds the input image image or its selected region, raised to power 2, to the accumulator sqsum :