C# - LockBit

reference

http://csharpexamples.com/fast-image-processing-c/







//// LockBits and Unsafe and parallel




private void ProcessUsingLockbitsAndUnsafeAndParallel(Bitmap processedBitmap)

{

    unsafe

    {

        BitmapData bitmapData = processedBitmap.LockBits(new Rectangle(0, 0, processedBitmap.Width, processedBitmap.Height), ImageLockMode.ReadWrite, processedBitmap.PixelFormat);

        int bytesPerPixel = System.Drawing.Bitmap.GetPixelFormatSize(processedBitmap.PixelFormat) / 8;

        int heightInPixels = bitmapData.Height;

        int widthInBytes = bitmapData.Width * bytesPerPixel;

        byte* PtrFirstPixel = (byte*)bitmapData.Scan0;

        Parallel.For(0, heightInPixels, y =>

        {

            byte* currentLine = PtrFirstPixel + (y * bitmapData.Stride);

            for (int x = 0; x < widthInBytes; x = x + bytesPerPixel)

            {

                int oldBlue = currentLine[x];

                int oldGreen = currentLine[x + 1];

                int oldRed = currentLine[x + 2];

                currentLine[x] = (byte)oldBlue;

                currentLine[x + 1] = (byte)oldGreen;

                currentLine[x + 2] = (byte)oldRed;

            }

        });

        processedBitmap.UnlockBits(bitmapData);

    }

}










//// LockBits and Unsafe

private void ProcessUsingLockbitsAndUnsafe(Bitmap processedBitmap)

{

    unsafe

    {

        BitmapData bitmapData = processedBitmap.LockBits(new Rectangle(0, 0, processedBitmap.Width, processedBitmap.Height), ImageLockMode.ReadWrite, processedBitmap.PixelFormat);

        int bytesPerPixel = System.Drawing.Bitmap.GetPixelFormatSize(processedBitmap.PixelFormat) / 8;

        int heightInPixels = bitmapData.Height;

        int widthInBytes = bitmapData.Width * bytesPerPixel;

        byte* ptrFirstPixel = (byte*)bitmapData.Scan0;

         

        for (int y = 0; y < heightInPixels; y++)

        {

            byte* currentLine = ptrFirstPixel + (y * bitmapData.Stride);

            for (int x = 0; x < widthInBytes; x = x + bytesPerPixel)

            {

                int oldBlue = currentLine[x];

                int oldGreen = currentLine[x + 1];

                int oldRed = currentLine[x + 2];

                // calculate new pixel value

                currentLine[x] = (byte)oldBlue;

                currentLine[x + 1] = (byte)oldGreen;

                currentLine[x + 2] = (byte)oldRed;

            }

        }

        processedBitmap.UnlockBits(bitmapData);

    }

}










//// LockBits and Marshal Copy

private void ProcessUsingLockbits(Bitmap processedBitmap)

{

    BitmapData bitmapData = processedBitmap.LockBits(new Rectangle(0, 0, processedBitmap.Width, processedBitmap.Height), ImageLockMode.ReadWrite, processedBitmap.PixelFormat);

     

    int bytesPerPixel = Bitmap.GetPixelFormatSize(processedBitmap.PixelFormat) / 8;

    int byteCount = bitmapData.Stride * processedBitmap.Height;

    byte[] pixels = new byte[byteCount];

    IntPtr ptrFirstPixel = bitmapData.Scan0;

    Marshal.Copy(ptrFirstPixel, pixels, 0, pixels.Length);

    int heightInPixels = bitmapData.Height;

    int widthInBytes = bitmapData.Width * bytesPerPixel;

    for (int y = 0; y < heightInPixels; y++)

    {

        int currentLine = y * bitmapData.Stride;

        for (int x = 0; x < widthInBytes; x = x + bytesPerPixel)

        {

            int oldBlue = pixels[currentLine + x];

            int oldGreen = pixels[currentLine + x + 1];

            int oldRed = pixels[currentLine + x + 2];

             

            // calculate new pixel value

            pixels[currentLine + x] = (byte)oldBlue;

            pixels[currentLine + x + 1] = (byte)oldGreen;

            pixels[currentLine + x + 2] = (byte)oldRed;

        }

    }

    // copy modified bytes back

    Marshal.Copy(pixels, 0, ptrFirstPixel, pixels.Length);

    processedBitmap.UnlockBits(bitmapData);

}










//// getPixel/setPixel

private void ProcessUsingGetPixelSetPixel(Bitmap processedBitmap)

{

    int width = processedBitmap.Width;

    int height = processedBitmap.Height;

    for (int x = 0; x < width; x++)

    {

        for (int y = 0; y < height; y++)

        {

            Color oldPixel = processedBitmap.GetPixel(x, y);

             

            // calculate new pixel value

            Color newPixel = oldPixel;

            processedBitmap.SetPixel(x, y, newPixel);

        }

    }

}




////

////

[ LockBits() ] private void btnChangColor_Click(object sender, EventArgs e) { Stopwatch sw = new Stopwatch(); sw.Start(); Rectangle rect = new Rectangle(0, 0, img.Width, img.Height); System.Drawing.Imaging.BitmapData bmpData = img.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, img.PixelFormat); // Get the address of the first line. IntPtr ptr = bmpData.Scan0; // Declare an array to hold the bytes of the bitmap. int bytes = Math.Abs(bmpData.Stride) * img.Height; byte[] rgbValues = new byte[bytes]; System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes); int numBytes = 0; for (int y = 0; y < img.Height; y++) { for (int x = 0; x < img.Width; x++) { numBytes = (y * (img.Width * 4)) + (x * 4); if (rgbValues[numBytes] != 255 && rgbValues[numBytes + 1] != 255 && rgbValues[numBytes + 2] != 255) { rgbValues[numBytes] = 0; rgbValues[numBytes + 1] = 0; rgbValues[numBytes + 2] = 255; } } } // Copy the RGB values back to the bitmap System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes); // Unlock the bits. img.UnlockBits(bmpData); pictureBox1.Invalidate(); sw.Stop(); MessageBox.Show(sw.ElapsedMilliseconds.ToString() + "ms"); } [SetPixel() / GetPixel()] private void btnChangColor02_Click(object sender, EventArgs e) { Stopwatch sw = new Stopwatch(); sw.Start(); Color co; for (int y = 0; y < img.Height; y++) { for (int x = 0; x < img.Width; x++) { co = img.GetPixel(x, y); if (co.R != 255 && co.G != 255 && co.B != 255) { co = Color.FromArgb(255, 0, 0); img.SetPixel(x, y, co); // 해당 좌표 픽셀의 컬러값을 변경 } } } pictureBox1.Invalidate(); sw.Stop(); MessageBox.Show(sw.ElapsedMilliseconds.ToString() + "ms"); }