Separated median filtering with rectangle masks.
The operator ::median_separate carries out a variation of the median filtering: First two auxiliary images are created. The first one originates from a median filtering with a horizontal mask with a height of one pixel and the width MaskWidth followed by filtering with a mask with the height MaskHeight. The second auxiliary image is created by filtering with the same masks, but with a reversed sequence of the operation: first the vertical, then the horizontal mask. The output image results from averaging the two auxiliary images pixel by pixel.
The operator ::median_separate is clearly faster than the normal operator ::median_image because both masks are one pixel wide, facilitating a very effecient processing. The runtime is practically independent of the size of the mask. For example, the operator ::median_separate can be well used after texture filters, where large masks are needed.
The filter can also be used several times in a row in order to enhance the smoothing.
|
Image (input_object) |
(multichannel-)image(-array) -> Hobject: HImage(Array) ( byte ) |
| Image to be filtered. | |
|
ImageSMedian (output_object) |
(multichannel-)image(-array) -> Hobject * : HImage(Array) ( byte ) |
| Median filtered image. | |
|
MaskWidth (input_control) |
extent.x -> HTuple.long |
| Width of rank mask. | |
| Default value: 25 | |
| Suggested values: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 27, 43, 51, 67, 91, 121, 151 | |
| Typical range of values: 1 <= MaskWidth <= 401 | |
| Minimum increment: 2 | |
|
Recommended increment: 2 | |
|
MaskHeight (input_control) |
extent.y -> HTuple.long |
| Height of rank mask. | |
| Default value: 25 | |
| Suggested values: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 27, 43, 51, 67, 91, 121, 151 | |
| Typical range of values: 1 <= MaskHeight <= 401 | |
| Minimum increment: 2 | |
|
Recommended increment: 2 | |
|
Margin (input_control) |
integer -> HTuple.long |
| Margin control: 0...255 (constant), -1 (edge pixels continued), -2 (cyclic continuation), -3 (reflection). | |
| Default value: -3 | |
| Typical range of values: -3 <= Margin <= 255 | |
| Minimum increment: 1 | |
|
Recommended increment: 1 | |
read_image(&Image,"fabrik"); median_separate(Image,&MedianSeparate,5,5,3); disp_image(MedianSeparate,WindowHandle);
For each pixel: O(40).
::texture_laws, ::sobel_amp, ::deviation_image
::learn_ndim_norm, ::learn_ndim_box, ::median_separate, ::regiongrowing, ::auto_threshold
R. Haralick, L. Shapiro; ``Computer and Robot Vision''; Addison-Wesley, 1992, Seite 319
Image filters
