[C#/WINFORM] Bitmap 클래스 : 중앙값 필터(Median Filter) 사용하기

TestProject.zip

다운로드

▶ BitmapHelper.cs

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

namespace TestProject
{
    /// <summary>
    /// 비트맵 헬퍼
    /// </summary>
    public static class BitmapHelper
    {
        //////////////////////////////////////////////////////////////////////////////////////////////////// Method
        ////////////////////////////////////////////////////////////////////////////////////////// Static
        //////////////////////////////////////////////////////////////////////////////// Public

        #region 비트맵 로드하기 - LoadBitmap(filePath)

        /// <summary>
        /// 비트맵 로드하기
        /// </summary>
        /// <param name="filePath">파일 경로</param>
        /// <returns>비트맵</returns>
        public static Bitmap LoadBitmap(string filePath)
        {
            using(Bitmap bitmap = new Bitmap(filePath))
            {
                return new Bitmap(bitmap);
            }
        }

        #endregion
        #region 중앙값 필터 적용하기 - ApplyMedianFilter(sourceBitmap, matrixSize, bias, grayscale)

        /// <summary>
        /// 중앙값 필터 적용하기
        /// </summary>
        /// <param name="sourceBitmap">소스 비트맵</param>
        /// <param name="matrixSize">매트릭스 크기</param>
        /// <param name="bias">바이어스</param>
        /// <param name="grayscale">회색조 여부</param>
        /// <returns>비트맵</returns>
        public static Bitmap ApplyMedianFilter(Bitmap sourceBitmap, int matrixSize, int bias = 0, bool grayscale = false)
        {
            BitmapData sourceBitmapData = sourceBitmap.LockBits
            (
                new Rectangle (0, 0, sourceBitmap.Width, sourceBitmap.Height),
                ImageLockMode.ReadOnly,
                PixelFormat.Format32bppArgb
            );

            byte[] sourceByteArray = new byte[sourceBitmapData.Stride * sourceBitmapData.Height];
            byte[] targetByteArray = new byte[sourceBitmapData.Stride * sourceBitmapData.Height];

            Marshal.Copy(sourceBitmapData.Scan0, sourceByteArray, 0, sourceByteArray.Length);

            sourceBitmap.UnlockBits(sourceBitmapData);

            if(grayscale == true)
            {
                float rgb = 0;

                for(int k = 0; k < sourceByteArray.Length; k += 4)
                {
                    rgb =  sourceByteArray[k    ] * 0.11f;
                    rgb += sourceByteArray[k + 1] * 0.59f;
                    rgb += sourceByteArray[k + 2] * 0.3f;

                    sourceByteArray[k    ] = (byte )rgb;
                    sourceByteArray[k + 1] = sourceByteArray[k];
                    sourceByteArray[k + 2] = sourceByteArray[k];
                    sourceByteArray[k + 3] = 255;
                }
            }

            int filterOffset = (matrixSize - 1) / 2;
            int sourceOffset = 0;
            int targetOffset = 0;

            List<int> neighbourPixelList = new List<int>();
            byte[]    middlePixelArray;

            for(int offsetY = filterOffset; offsetY < sourceBitmap.Height - filterOffset; offsetY++)
            {
                for(int offsetX = filterOffset; offsetX < sourceBitmap.Width - filterOffset; offsetX++)
                {
                    targetOffset = offsetY * sourceBitmapData.Stride + offsetX * 4;

                    neighbourPixelList.Clear();

                    for(int filterY = -filterOffset; filterY <= filterOffset; filterY++)
                    {
                        for(int filterX = -filterOffset; filterX <= filterOffset; filterX++)
                        {
                            sourceOffset = targetOffset + (filterX * 4) + (filterY * sourceBitmapData.Stride);

                            neighbourPixelList.Add(BitConverter.ToInt32(sourceByteArray, sourceOffset));
                        }
                    }

                    neighbourPixelList.Sort();

                    middlePixelArray = BitConverter.GetBytes(neighbourPixelList[filterOffset]);

                    targetByteArray[targetOffset    ] = middlePixelArray[0];
                    targetByteArray[targetOffset + 1] = middlePixelArray[1];
                    targetByteArray[targetOffset + 2] = middlePixelArray[2];
                    targetByteArray[targetOffset + 3] = middlePixelArray[3];
                }
            }

            Bitmap targetBitmap = new Bitmap(sourceBitmap.Width, sourceBitmap.Height);

            BitmapData targetBitmapData = targetBitmap.LockBits
            (
                new Rectangle (0, 0, targetBitmap.Width, targetBitmap.Height),
                ImageLockMode.WriteOnly,
                PixelFormat.Format32bppArgb
            );

            Marshal.Copy(targetByteArray, 0, targetBitmapData.Scan0, targetByteArray.Length);

            targetBitmap.UnlockBits(targetBitmapData);

            return targetBitmap;
        }

        #endregion
    }
}

 

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▶ MainForm.cs

using System.Drawing;
using System.Windows.Forms;

namespace TestProject
{
    /// <summary>
    /// 메인 폼
    /// </summary>
    public partial class MainForm : Form
    {
        //////////////////////////////////////////////////////////////////////////////////////////////////// Constructor
        ////////////////////////////////////////////////////////////////////////////////////////// Public

        #region 생성자 - MainForm()

        /// <summary>
        /// 생성자
        /// </summary>
        public MainForm()
        {
            InitializeComponent();

            Bitmap sourceBitmap = BitmapHelper.LoadBitmap("IMAGE\\sample.jpg");
            Bitmap targetBitmap = BitmapHelper.ApplyMedianFilter(sourceBitmap, 3, 0, false);

            this.pictureBox.SizeMode = PictureBoxSizeMode.Zoom;
            this.pictureBox.Image    = targetBitmap;
        }

        #endregion
    }
}