A Rotation Invariant Filter for Two-Dimensional String Matching
نویسندگان
چکیده
We consider the problem of nding the occurrences of two{ dimensional pattern P1::m;1::m] in two{dimensional text T1::n; 1::n] when also rotations of P are allowed. A fast ltration{type algorithm is developed that nds in T the locations where a rotated P can occur. The corresponding rotations are also found. The algorithm rst reads from P a linear string of length m in all O(m 2) orientations that are relevant. We also show that the number of diierent orientations which P can have is O(m 3). The text T is scanned with Aho{Corasick string matching automaton to nd the occurrences of any of these O(m 2) linear strings of length m. Each such occurrence indicates a potential set of occurrences of whole P which are then checked. Some preliminary running times of a prototype implementation of the method are reported.
منابع مشابه
A New RSTB Invariant Image Template Matching Based on Log-Spectrum and Modified ICA
Template matching is a widely used technique in many of image processing and machine vision applications. In this paper we propose a new as well as a fast and reliable template matching algorithm which is invariant to Rotation, Scale, Translation and Brightness (RSTB) changes. For this purpose, we adopt the idea of ring projection transform (RPT) of image. In the proposed algorithm, two novel s...
متن کاملA Rotation Invariant Filter for Two–dimensional String Matching1
We consider the problem of finding the occurrences of two– dimensional pattern P [1..m, 1..m] in two–dimensional text T [1..n, 1..n] when also rotations of P are allowed. A fast filtration–type algorithm is developed that finds in T the locations where a rotated P can occur. The corresponding rotations are also found. The algorithm first reads from P a linear string of length m in all O(m) orie...
متن کاملImage Matching Based on Scale Invariant Regions
In this paper we present a novel approach to match two images in presenting large scale and rotation changes. The proposed approach is based on scale invariant region description. Scale invariant region is detected by a two-step process and represented by a new descriptor. The descriptor is a two-dimensional gray-level histogram. Different descriptors can be directly compared. In addition, our ...
متن کاملRotationally invariant similarity measures for nonlocal image denoising
Many natural or texture images contain structures that appear several times in the image. One of the denoising filters that successfully take advantage of such repetitive regions is the nonlocal means filter. It is simple and yields very good denoising results. Unfortunately, the block matching within the standard nonlocal means filter is not able to handle rotation or mirroring. Rotated or mir...
متن کاملRestricted Transposition Invariant Approximate String Matching Under Edit Distance
Let A and B be strings with lengths m and n, respectively, over a finite integer alphabet. Two classic string mathing problems are computing the edit distance between A and B, and searching for approximate occurrences of A inside B. We consider the classic Levenshtein distance, but the discussion is applicable also to indel distance. A relatively new variant [8] of string matching, motivated in...
متن کامل