mean_sp ( Image : ImageSPMean : MaskWidth, MaskHeight, MinThresh, MaxThresh : )

Suppress salt and pepper noise.

The operator mean_sp carries out a smoothing by averaging the values. Only the gray values within the interval from MinThresh to MaxThresh are averaged. Gray values which are too light or too dark are ignored during summation. If no gray value lies within the default interval during summation the original gray value is adopted. If the thresholds are set at 0 or 255, respectively, the operator mean_sp behaves like mean__ except for the running time.

The operator mean_sp is used to suppress extreme gray values (salt and pepper noise = white and black dots).


Attention

If even values instead of odd values are given for MaskHeight or MaskWidth, the routine uses the next larger odd values instead (this way the center of the filter mask is always explicitly determined).


Parameters

Image (input_object)
image(-array) -> object : byte
Input image

ImageSPMean (output_object)
image(-array) -> object : byte
Smoothed image

MaskWidth (input_control)
extent.x -> integer
Width of filter mask.
Default value: 3
Suggested values: 3, 5, 7, 9, 11
Range of values: 3 <= MaskWidth <= 512 (lin)
Minimum increment: 2
Recommended increment: 2
Restriction: odd(MaskWidth)

MaskHeight (input_control)
extent.y -> integer
Height of filter mask.
Default value: 3
Suggested values: 3, 5, 7, 9, 11
Range of values: 3 <= MaskHeight <= 512 (lin)
Minimum increment: 2
Recommended increment: 2
Restriction: odd(MaskHeight)

MinThresh (input_control)
integer -> integer
Minimum gray value
Default value: 1
Suggested values: 1, 5, 7, 9, 11, 15, 23, 31, 43, 61, 101
Range of values: 0 <= MinThresh <= 255 (lin)
Minimum increment: 1
Recommended increment: 1

MaxThresh (input_control)
integer -> integer
Maximum gray value
Default value: 254
Suggested values: 5, 7, 9, 11, 15, 23, 31, 43, 61, 101, 200, 230, 250, 254
Range of values: 0 <= MaxThresh <= 255 (lin)
Minimum increment: 1
Recommended increment: 1
Restriction: MinThresh <= MaxThresh


Example
read_image(:Image:'meer_rot':) >
disp_image(Image:::) >
mean_sp(Image,ImageMeansp:3,3,101,201::) >
disp_image(ImageMeansp:::).

Possible Successors

disp_image


Alternatives

mean__, median, median_separate


See also

anisotrope_diff__, sigma__, gauss__, smooth__



Copyright © 1996-1997 MVTec Software GmbH