gradient
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Input
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An integer between 0 and 116 specifying the input image frame number. A value of 0 represents the DMA memory buffer of the video device. Values in the range of 100-116 correspond to hidden frames.
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Output
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An integer between 1 and 116 specifying the output image frame number. Values in the range of 100-116 correspond to hidden frames.
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Size
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An odd integer between 1 and 2*Overscan+1 specifying the width of the gradient window.
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Mode
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An optional enumerated integer that describes how the two differential images are combined. Must be one of the following values:
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M_HORZ the target pixel is substituted with the corresponding pixel from the horizontal differential image::
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M_VERT the target pixel is substituted with the corresponding pixel from the vertical differential image:
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M_MEAN the target pixel substituted with the mean of the absolute values of the corresponding pixels in two differential images:
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Default value: 2
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Invert
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An optional boolean integer specifying if the outcome of the function should be inverted. Must be one of the following values:
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FALSE the direct mode. Edges are presented as bright lines on a dark background.
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TRUE the inverse mode. Edges are presented as dark lines on a bright background.
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Default: FALSE
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ERR_OK
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The flag set if successful.
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ERR_FAILED
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The flag set if failed.
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This set of statements continuously captures an image and performs detection of vertical edges by applying the gradient filter:
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do
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grabIm (0)
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gradient (0, 1, M_VERT)
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loop while getError()=ERR_OK
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When the Mode is set to M_PHASE, the phase values will be calculated differently depending on the type of an image. If an image is of an integer type, the target pixel representing the angle of the intensity gradient will be rescaled so the range of possible angular values (0° -359°) will be mapped on the entire intensity scale of the image. If an image is of a floating type, the phase will be reported in radians, while the absence of the gradient will be indicated by pixels with the value of negative 1.
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