using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Drawing.Imaging;

namespace WindowsFormsApplication5

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        public static void ChangeOpacity(PictureBox pb, Single opacity, Control parent)

        {

            var img = pb.Image;

            var bmp = new Bitmap(img.Width, img.Height);

            using (var g = Graphics.FromImage(bmp))

            {

                var colorMatrix = new ColorMatrix();

                colorMatrix.Matrix33 = opacity;

                var attr = new ImageAttributes();

                attr.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);

                g.DrawImage(img, new Rectangle(, , bmp.Width, bmp.Height), , , img.Width, img.Height, GraphicsUnit.Pixel, attr);

            }

            pb.BackColor = Color.Transparent;

            pb.Image = bmp;

            pb.Parent = parent;

            pb.Left = ;

            pb.Top = ;

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            ChangeOpacity(pictureBox1, 0.3F, button1);

        }

    }

}