IDIFF-Takes the 'differential' of an image

Description:

IDIFF takes an input image and creates a new image where each pixel is the average absolute difference between the corresponding pixel in the original image and its nearest neighbours. This emphasises those regions in the image where the data is changing rapidly.

Parameters:

IMAGE

IMAGE must contain two-dimensional data. IDIFF creates a resulting image where each pixel is the average absol- ute difference between the corresponding pixel in IMAGE and its nearest neighbours.

OUTPUT

The name of the resulting image. If this is the same as IMAGE (the default) the operation will be performed in situ. Otherwise a new image will be created.

Source comments:

 I D I F F

 Given an image, creates a new image in which each pixel
 is the average absolute difference between the corresponding
 pixel in the input image and its immediate neighbours.  This
 highlights regions in the image where the data is changing
 rapidly.

 Command parameters -

 IMAGE  The name of the structure containing the image.

 OUTPUT The name of the result of the operation.  This can
        be the same as for IMAGE.  If not, a new structure
        is created, with everything but the data a direct
        copy of the input.

 Command keywords  - None

 User variables used - None
                                  KS / CIT 22nd April 1984