mean_sp (Operator)

Name

mean_sp — Suppress salt and pepper noise.

Synopsis

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

Description

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_image 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)	(multichannel-)image(-array) → object (byte / uint2)
Input image.

ImageSPMean (output_object)	(multichannel-)image(-array) → object (byte / uint2)
Smoothed image.

MaskWidth (input_control)	extent.x → (integer)
Width of filter mask.
Default value: 3
Suggested values: 3, 5, 7, 9, 11
Typical 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
Typical 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

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
Restriction: MinThresh <= MaxThresh

Example

read_image(Image,'mreut')
disp_image(Image,WindowHandle)
mean_sp(Image,ImageMeansp,3,3,101,201)
disp_image(ImageMeansp,WindowHandle)

Parallelization Information

mean_sp is reentrant and automatically parallelized (on tuple level, channel level, domain level).

Possible Successors

disp_image

Alternatives

mean_image, median_image, median_separate, eliminate_min_max

See also

anisotropic_diffusion, sigma_image, binomial_filter, gauss_image, smooth_image, eliminate_min_max

Module

Foundation