Transparent Layer On Image

using System.Drawing.Drawing2D;

privatestaticImage fill_layer(PictureBox Pic_Box,Image img,Color Layer_color,int Percent)
{
//از img به عنوان بک آپ استفاده می شود
//percent درصد شفافیت است
Pic_Box.Image = img;
Bitmap bmp_img = newBitmap(Pic_Box.Image);
Graphics ghp = Graphics.FromImage(bmp_img);
LinearGradientBrush LineaBrush;
LineaBrush = newLinearGradientBrush(newRectangle(0, 0, bmp_img.Width, bmp_img.Height), Color.FromArgb(Percent, Layer_color), Color.FromArgb(Percent, Layer_color), LinearGradientMode.BackwardDiagonal);
ghp.FillRectangle(LineaBrush, newRectangle(0, 0, bmp_img.Width, bmp_img.Height));
return (Image)bmp_img;
}

pictureBox1.Image = fill_layer(pictureBox1,pictureBox2.Image, Color,Value);