在 C# 中更快地反转图像

Question

我正在使用 WinForms。我的表格中有一个图片框。当我在图片框中打开图片时，我可以通过单击按钮来回反转颜色，但是我的代码非常慢。我怎样才能提高性能。

   private void Button1_Click(object sender, System.EventArgs e) 
     {
        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 1

每次更改像素时都会设置控件的图片，这会导致控件重绘自身。等到你完成图像：

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

如果有人需要 VB.NET 中的类似代码。

还要注意变量 inv.A 而不是值 255。如果你的图片框有透明度，你需要这个。

    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

用法：

    pic.image = InvertImageColors(pic.image)

Answer 3

这对我有用...

        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;
    }