Question

That is the solution to make a negative from a image in C# Windows Forms without any dlls and in a effective, fast way?

Answer 1

The best way to do this is directly accessing the pixels with bitmap data.

Just to add some timing details:

Performing Negate on an 8 Megapixel Image (on a 2.4 Ghz Core 2 Duo):

• SetPixel (~22 seconds) – 220 Times slower
• Color Matrix, Matajon’s method below (~750 milliseconds) – 7 times slower
• Directly accesing the bitmap data (~100 milliseconds) – Fastest

So, if you can’t have unsafe code, then Color Matrix is much better than SetPixel.

    public static void Negate(Bitmap image)     {         const int RED_PIXEL = 2;         const int GREEN_PIXEL = 1;         const int BLUE_PIXEL = 0;           BitmapData bmData = currentImage.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadWrite, image.PixelFormat);          try         {             int stride = bmData.Stride;             int bytesPerPixel = (currentImage.PixelFormat == PixelFormat.Format24bppRgb ? 3 : 4);              unsafe             {                 byte* pixel = (byte*)(void*)bmData.Scan0;                 int yMax = image.Height;                 int xMax = image.Width;                  for (int y = 0; y < yMax; y++)                 {                     int yPos = y * stride;                     for (int x = areaSize.X; x < xMax; x++)                     {                         int pos = yPos + (x * bytesPerPixel);                          pixel[pos + RED_PIXEL] = (byte)(255 - pixel[pos + RED_PIXEL]);                         pixel[pos + GREEN_PIXEL] = (byte)(255 - pixel[pos + GREEN_PIXEL]);                         pixel[pos + BLUE_PIXEL] = (byte)(255 - pixel[pos + BLUE_PIXEL]);                                                                         }                  }             }         }         finally         {             image.UnlockBits(bmData);         }      } 

If you are interested, here is the code for Color Matrix:

    public static void Negate(Bitmap image)     {              Bitmap clone = (Bitmap) image.Clone();              using (Graphics g = Graphics.FromImage(image))             {                  // negation ColorMatrix                 ColorMatrix colorMatrix = new ColorMatrix(                     new float[][]                         {                             new float[] {-1, 0, 0, 0, 0},                             new float[] {0, -1, 0, 0, 0},                             new float[] {0, 0, -1, 0, 0},                             new float[] {0, 0, 0, 1, 0},                             new float[] {0, 0, 0, 0, 1}                         });                  ImageAttributes attributes = new ImageAttributes();                  attributes.SetColorMatrix(colorMatrix);                  g.DrawImage(clone, new Rectangle(0, 0, clone.Width, clone.Height),                             0, 0, clone.Width, clone.Height, GraphicsUnit.Pixel, attributes);            }     }