Invert image faster in C#

Question

I\'m using WinForms. I have a picture-box in my form. When I open a picture in the picture-box I am able to invert the colors back and forth on a click of a button, but my c

Answer 1

You are setting the control's picture each time you change a pixel, which causes the control to redraw itself. Wait until you've finished the image:

Bitmap pic = new Bitmap(PictureBox1.Image);
for (int y = 0; (y <= (pic.Height - 1)); y++) {
    for (int x = 0; (x <= (pic.Width - 1)); x++) {
        Color inv = pic.GetPixel(x, y);
        inv = Color.FromArgb(255, (255 - inv.R), (255 - inv.G), (255 - inv.B));
        pic.SetPixel(x, y, inv);
    }
}
PictureBox1.Image = pic;

Answer 2

In case someone need the similar code in VB.NET.

Also note the variable inv.A instead of the value 255. In case your picturebox has transparency you need this.

    Public Function InvertImageColors(ByVal p As Image) As Image
        Dim pic As New Bitmap(p)
        For y As Integer = 0 To pic.Height - 1
            For x As Integer = 0 To pic.Width - 1
                Dim inv As Color = pic.GetPixel(x, y)
                inv = Color.FromArgb(inv.A, 255 - inv.R, 255 - inv.G, 255 - inv.B)
                pic.SetPixel(x, y, inv)
            Next x
        Next y
        Return pic
    End Function

Usage:

    pic.image = InvertImageColors(pic.image)

Answer 3

It`s work for me...

        private Image InvertingImage(Image source)
    {
        //create a blank bitmap the same size as original
        Bitmap newBitmap = new Bitmap(source.Width, source.Height);

        //get a graphics object from the new image
        Graphics g = Graphics.FromImage(newBitmap);

        // create the negative color matrix
        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[] {1, 1, 1, 0, 1}
});

        // create some image attributes
        ImageAttributes attributes = new ImageAttributes();

        attributes.SetColorMatrix(colorMatrix);

        g.DrawImage(source, new Rectangle(0, 0, source.Width, source.Height),
                    0, 0, source.Width, source.Height, GraphicsUnit.Pixel, attributes);

        //dispose the Graphics object
        g.Dispose();

        return newBitmap;
    }