버전 1.0.0 (21.1 KB) 작성자: Peter Cook
C-MEX for 2D Rolling Median
다운로드 수: 38
업데이트 날짜: 2019/6/26

B = rollingMedian(A, R, C) Performs median filtering of the
matrix A in two dimensions with minimal edge effects and phase shift.
A : Input Array
Dimensions Allowed: (M x N), (M x N x ?), (M x N x ? x ?), ...
As long as the leading dimensions of A (M & N) are nonzero, the
filter will operate on all trailing dimensions.
R : Filter Window Rows (1 < R < M / 2)
C : Filter Window Cols (1 < C < N / 2)

B : Output Array with the same dimensions and class as A.

rollingMedian uses a median-heap to compute the rolling median rather
than a sorting approach (i.e. sort all elements for each window).
The time complexity of a sorting approach (for e.g. quicksort, mergesort) is
The time complexity of the median heap approach is O(M*N*log(R*C)).

Edge Effects
The left and right edges (1) are filtered first using
successively wider filter windows for all pixels whose col index is less
than C/2. The top and bottom edges (2) are filtered second using
successively taller filter windows for all pixels whose row index is less
than R/2.

Phase Distortion
The algorithm operates on 4 pointers simultaneously (one for each of the
top-left, bottom-left, top-right, and bottom-right of the array) and
moves from the edges of the array inward. This creates a south-east phase
shift in the top-left quadrant, a north-east phase shift in the
bottom-left quadrant, a south-west phase shift for the top-right quadrant,
and a north-west phase shift in the bottom right quadrant. This may
create distortion at N/2 if C is even, and M/2 if R is even. If M or N is odd,
the median windows from both sides are advanced one row or col and the average
of both sides is used.

Filter Window Passes
1a: cols 0 to C/2-1, rows 0 to M/2-1
1b: cols 0 to C/2-1, rows M-1 to M-M/2 (reverse)
1c: cols N-1 to N-C/2 (reverse), rows 0 to M/2-1
1d: cols N-1 to N-C/2 (reverse), rows M-1 to M-M/2 (reverse)
1B: if M%2 : (cols 0 to C/2-1, row M/2) & (col N-1 to N-C/2 (reverse), row M/2)
2a: cols C/2 to N/2-1, rows 0 to R/2-1
2b: cols C/2 to N/2-1, rows M-1 to M-R/2 (reverse)
2c: cols N-C/2-1 to N-N/2 (reverse), rows 0 to R/2-1
2d: cols N-C/2-1 to N-N/2 (reverse), rows M-1 to M-R/2 (reverse)
2B: if N%2 : (col N/2, rows 0 to R/2-1) & (cols N/2, rows M-1 to M-R/2 (reverse))
3a: cols C/2 to N/2-1, rows R/2 to M/2-1
3b: cols C/2 to N/2-1, rows M-R/2-1 to M-M/2 (reverse)
3c: cols N-C/2-1 to N-N/2 (reverse), rows M/2 to M/2-1
3d: cols N-C/2-1 to N-N/2 (reverse), rows M-R/2-1 to M-M/2 (reverse)
3B: if N%2 : (col N/2, row R/2 to M/2-1) & (col N/2, rows M-R/2-1 to M-M/2 (reverse))
3C: if M%2 : (cols C/2 to N/2-1, row M/2) & (cols N-C/2-1 to N-N/2 (reverse), row M/2)
3D: if M%2 & N%2: average of 3B & 3C at (col N/2, row M/2)

Class Support
uint8, int8, uint16, int16, uint32, int32, uint64, int64, float, double

Peter Cook 2019

인용 양식

Peter Cook (2024). rollingMedian (, GitHub. 검색됨 .

MATLAB 릴리스 호환 정보
개발 환경: R2016b
모든 릴리스와 호환
플랫폼 호환성
Windows macOS Linux
Help CenterMATLAB Answers에서 Programming에 대해 자세히 알아보기

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

GitHub 디폴트 브랜치를 사용하는 버전은 다운로드할 수 없음

버전 게시됨 릴리스 정보

이 GitHub 애드온의 문제를 보거나 보고하려면 GitHub 리포지토리로 가십시오.
이 GitHub 애드온의 문제를 보거나 보고하려면 GitHub 리포지토리로 가십시오.