distance

distance ( integer Input, integer Output, integer Mode, integer Multiphase =FALSE,

integer Invert =FALSE )

Use this function to perform the distance transform of a multiphase image or selection. The function works by assigning each foreground pixel a value equal to its distance from the nearest background pixel. The metric used for computing the digital distance depends on the Mode selected.

Parameters

Input

An integer between 1 and 116 specifying the input image frame number. 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 metric used to calculate a distance:

M_CITY=0 – uses a 4-connected metric (city block). Only vertical and horizontal movements are allowed.

M_CHESS=1 – uses an 8-connected metric (chess board). Vertical, horizontal and horizontal movements are allowed.

M_CHAMFER=2 – uses an 8-connected metric where vertical and horizontal movements are weighted with a weight of 3, while diagonal movements are weighted with a weight of 4.

M_EUCLID=3 –approximates Euclidian distance.

Multiphase

A boolean integer specifying weather the output image must be of the 16-bit grayscale or multiphase type. Must be one of the following values:

FALSE=0 – creates a 16-bit grayscale output image

TRUE=1 – creates a multiphase output image which makes a distance map more perceptible due to steep color differences between adjacent levels, but limits it to the maximum distance of 256 pixels.

Default value: FALSE

Invert

A boolean integer specifying weather the distance map must be computed for foreground or background pixels.

FALSE=0 – computes the distance map for foreground pixels. Each pixel in the output image is assigned a value equal to its distance from the nearest background pixel in the input image.

TRUE=1 – computes the distance map for background pixels. Each pixel in the output image is assigned a value equal to its distance from the nearest foreground pixel in the input image.

Default value: FALSE.

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 builds its distance map in two form, 16-bit grayscale and multiphase:.

setCurDir ("samples")

loadIm (1,"sample25.iwd")

threshold(1,1,M_PRESET,180.,255.,TRUE,FALSE)

fill(1,1)

distance(1,2,M_EUCLIDIAN)

distance (1,3,M_EUCLIDIAN,TRUE)