contour

contour ( integer Input, integer Output , integer Mode, integer Probe )

Use this function to extract contours of objects in an image or selection. The function is based on the morphological gradient which works by combining the original image with the results of the erode or dilate functions. The way these images are combined depends on the Mode chosen. The shape and size of the neighborhood pattern for the operation is selected with the Probe parameter.
Parameters

Input

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.

Output

An integer between 1 and 116 specifying the output image frame number. Values in the range of 100-116 correspond to hidden frames.

Mode

An enumerated integer that describes the mode in which the function operates. Must be one of the following values:

M_INTERNAL=0 – extracts the internal contours of objects by subtracting the eroded image from the original one.

M_EXTERNAL=1 – extracts the external contours of objects by subtracting the original image from the one.

M_BOTH=2 – extracts both the internal and external contours of objects by subtracting the eroded image from the dilated one.

Probe

An enumerated integer that describes the shape and size of the kernel used in the operation. Select one of the following frequently used shapes:

PR_VBAR=1 – vertical bar

PR_BKSLASH=2 – diagonal bar (top left – bottom right)

PR_HBAR=4 – horizontal bar

PR_FWSLASH=8 –diagonal bar (bottom left – top right)

PR_CROSS=5 – cross 3x3

PR_DCROSS=10 – diagonal cross 3x3

PR_SQUARE=15 – square 3x3

PR_CIRCLE=16 – circle 5x5

Error flags

ERR_OK

The flag set if successful.

ERR_FAILED

The flag set if failed.

Example

This set of statements binarizes a sample image and extracts the internal contours of objects:

setCurDir ("samples")

loadIm (1,"sample4.iwd")

threshold(1,1,M_PRESET,0.,113.,TRUE,FALSE)

contour(1,2,0,15)