From 2db512ac95a782f6bb35b7c45475a33f73b6f252 Mon Sep 17 00:00:00 2001
From: Timothee Floure
Date: Wed, 28 Oct 2015 11:15:28 +0100
Subject: Filter : allow to handle any kernel size (H*N : H and N odd)

---
 src/main/java/Filter.java | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/main/java/Filter.java b/src/main/java/Filter.java
index 4e06800..7e55f04 100644
--- a/src/main/java/Filter.java
+++ b/src/main/java/Filter.java
@@ -51,17 +51,36 @@ public final class Filter {
     public static float[][] filter(float[][] gray, float[][] kernel) {
         int width = gray[0].length;
         int height = gray.length;
+
+        int kernelWidth = kernel[0].length;
+        int kernelHeight = kernel.length;
+
+        float pixelNeighbors[][] = new float[kernelHeight][kernelWidth];
         float[][] filteredImage = new float[height][width];
+
         for (int row = 0; row < height; ++row) {
             for (int col = 0; col < width; ++col) {
-                float pixelNeighbors[][] = {
-                        {Filter.at(gray, row - 1, col - 1), Filter.at(gray, row - 1, col), Filter.at(gray, row - 1, col + 1)},
-                        {Filter.at(gray, row, col - 1), Filter.at(gray, row, col), Filter.at(gray, row, col + 1)},
-                        {Filter.at(gray, row + 1, col - 1), Filter.at(gray, row + 1, col), Filter.at(gray, row + 1, col + 1)}
-                };
-
-                for (int i = 0; i < kernel[0].length; i++) {
-                    for (int j = 0; j < kernel.length; j++) {
+
+                int pixelRow = -kernelHeight / 2;
+                int pixelCol = -kernelWidth / 2;
+
+                for (int kernelRow = 0; kernelRow < kernelWidth; kernelRow++) {
+                    for (int kernelCol = 0; kernelCol < kernelHeight; kernelCol++) {
+                        pixelNeighbors[kernelRow][kernelCol] = Filter.at(gray, row + pixelRow, col + pixelCol);
+
+                        pixelCol += 1;
+                        if (pixelCol > kernelWidth / 2) {
+                            pixelCol = -kernelWidth / 2;
+                        }
+                    }
+                    pixelRow += 1;
+                    if (pixelRow > kernelHeight / 2) {
+                        pixelRow = -kernelHeight / 2;
+                    }
+                }
+
+                for (int i = 0; i < kernelWidth; i++) {
+                    for (int j = 0; j < kernelHeight; j++) {
                         filteredImage[row][col] += kernel[i][j] * pixelNeighbors[i][j];
                     }
                 }
-- 
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