如何在图形上绘制图像而在外边界处没有额外的像素？

Question

This simple code gives me very bad result.

            Image global_src_img = Image.FromFile(Application.StartupPath + "\\src.png");
            Image src_img = ((Bitmap)global_src_img).Clone(new Rectangle(160, 29, 8, 14), PixelFormat.Format32bppArgb);
            src_img.Save(Application.StartupPath + "\\src_clonned.png", ImageFormat.Png);
            Bitmap trg_bmp = new Bitmap(100, 100);
            Graphics gfx = Graphics.FromImage(trg_bmp);
            gfx.FillRectangle(new Pen(Color.FromArgb(255, 0, 0, 0)).Brush, 0, 0, trg_bmp.Width, trg_bmp.Height);
            gfx.DrawImageUnscaled(src_img, (trg_bmp.Width / 2) - (src_img.Width / 2), (trg_bmp.Height / 2) - (src_img.Height / 2));
            gfx.Dispose();
            trg_bmp.Save(Application.StartupPath + "\\trg.png", ImageFormat.Png);

It clones part of the big image with letters and writes it to another image. Written image has extra pixels at outer borders that does not present in source image same as in cloned image. How to avoid it?

This is cloned image ( src_clonned.png ) that later will be drawn on graphics.

This is saved resulting image ( trg.png ).

Answer 1

Draw directly on bitmap to avoid any pixels modifications with this:

public static void DrawImgOnImg(Image src, Bitmap trg, int x, int y)
{
    for (int i = x; i < x + src.Width; i++)
        for (int j = y; j < y + src.Height; j++)
        {
            Color src_px = ((Bitmap)src).GetPixel(i - x, j - y);
            trg.SetPixel(i, j, src_px);
        }
}