■ Bitmap 클래스에서 그라디언트 기반 가장자리 탐지 필터(Gradient Based Edge Detection Filter)를 사용하는 방법을 보여준다.
▶ BitmapHelper.cs
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using System; 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 그라디언트 기반 가장자리 탐지 필터 적용하기 - ApplyGradientBasedEdgeDetectionFilter(sourceBitmap, threshold) /// <summary> /// 그라디언트 기반 가장자리 탐지 필터 적용하기 /// </summary> /// <param name="sourceBitmap">소스 비트맵</param> /// <param name="threshold">임계치</param> /// <returns>비트맵</returns> public static Bitmap ApplyGradientBasedEdgeDetectionFilter(Bitmap sourceBitmap, byte threshold = 0) { 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); int offset = 0; int gradientValue = 0; bool exceedThreshold = false; for(int offsetY = 1; offsetY < sourceBitmap.Height - 1; offsetY++) { for(int offsetX = 1; offsetX < sourceBitmap.Width - 1; offsetX++) { offset = offsetY * sourceBitmapData.Stride + offsetX * 4; gradientValue = 0; exceedThreshold = true; CheckThreshold ( sourceByteArray, offset - 4, offset + 4, ref gradientValue, threshold, 2 ); exceedThreshold = CheckThreshold ( sourceByteArray, offset - sourceBitmapData.Stride, offset + sourceBitmapData.Stride, ref gradientValue, threshold, 2 ); if(exceedThreshold == false) { gradientValue = 0; exceedThreshold = CheckThreshold ( sourceByteArray, offset - 4, offset + 4, ref gradientValue, threshold ); if(exceedThreshold == false) { gradientValue = 0; exceedThreshold = CheckThreshold ( sourceByteArray, offset - sourceBitmapData.Stride, offset + sourceBitmapData.Stride, ref gradientValue, threshold ); if(exceedThreshold == false) { gradientValue = 0; CheckThreshold ( sourceByteArray, offset - 4 - sourceBitmapData.Stride, offset + 4 + sourceBitmapData.Stride, ref gradientValue, threshold, 2 ); exceedThreshold = CheckThreshold ( sourceByteArray, offset - sourceBitmapData.Stride + 4, offset - 4 + sourceBitmapData.Stride, ref gradientValue, threshold, 2 ); if(exceedThreshold == false) { gradientValue = 0; exceedThreshold = CheckThreshold ( sourceByteArray, offset - 4 - sourceBitmapData.Stride, offset + 4 + sourceBitmapData.Stride, ref gradientValue, threshold ); if(exceedThreshold == false) { gradientValue = 0; exceedThreshold = CheckThreshold ( sourceByteArray, offset - sourceBitmapData.Stride + 4, offset + sourceBitmapData.Stride - 4, ref gradientValue, threshold ); } } } } } targetByteArray[offset ] = (byte)(exceedThreshold ? 255 : 0); targetByteArray[offset + 1] = targetByteArray[offset]; targetByteArray[offset + 2] = targetByteArray[offset]; targetByteArray[offset + 3] = 255; } } 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 //////////////////////////////////////////////////////////////////////////////// Private #region 임계치 체크하기 - CheckThreshold(sourceByteArray, offset1, offset2, gradientValue, threshold, divideBy) /// <summary> /// 임계치 체크하기 /// </summary> /// <param name="sourceByteArray">소스 바이트 배열</param> /// <param name="offset1">오프셋 1</param> /// <param name="offset2">오프셋 2</param> /// <param name="gradientValue">그라디언트 값</param> /// <param name="threshold">임계치</param> /// <param name="divideBy">젯수</param> /// <returns>임계치 체크 결과</returns> private static bool CheckThreshold ( byte[] sourceByteArray, int offset1, int offset2, ref int gradientValue, byte threshold, int divideBy = 1 ) { gradientValue += Math.Abs(sourceByteArray[offset1 ] - sourceByteArray[offset2 ]) / divideBy; gradientValue += Math.Abs(sourceByteArray[offset1 + 1] - sourceByteArray[offset2 + 1]) / divideBy; gradientValue += Math.Abs(sourceByteArray[offset1 + 2] - sourceByteArray[offset2 + 2]) / divideBy; return (gradientValue >= threshold); } #endregion } } |
▶ MainForm.cs
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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.ApplyGradientBasedEdgeDetectionFilter(sourceBitmap, 250); this.pictureBox.SizeMode = PictureBoxSizeMode.Zoom; this.pictureBox.Image = targetBitmap; } #endregion } } |
