Replacing Colour Of An Image

Question

I am trying to replace the black colours of a picture with white, and vice versa. This is actually so my OCR code can read it on white backgrounds better. It\'s currently ge

Answer 1

You can use the ColorMap and ImageAttributes classes from the System.Drawimg.Imaging namespace to directly replace the pixels in your image:

Image img = Clipboard.GetImage();
if (img != null) {
  ColorMap[] cm = new ColorMap[1];
  cm[0] = new ColorMap();
  cm[0].OldColor = Color.Black;
  cm[0].NewColor = Color.White;
  ImageAttributes ia = new ImageAttributes();
  ia.SetRemapTable(cm);
  using (Graphics g = Graphics.FromImage(img)) {
    g.DrawImage(img, new Rectangle(Point.Empty, img.Size), 0, 0, img.Width, img.Height,
                GraphicsUnit.Pixel, ia);
  }
  pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
  pictureBox1.Image = img;
}