동구의 블로그

public partial class Form1 : Form

{

    public Form1()

    {

        InitializeComponent();

    }

    private void btnLoad_Click(object sender, EventArgs e)

    {

        OpenFileDialog of = new OpenFileDialog();

        if (of.ShowDialog() == DialogResult.OK)

        {

            try

            {

                this.SetImage(of.FileName);

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

        }

    }

    private void SetImage(string fileName)

    {

        try

        {

            Image img = Image.FromFile(fileName);

            this.pictureBox1.Image = ChangeOpacity(img, 0.5f);

            img.Dispose();

        }

        catch (Exception ex)

        {

            throw ex;

        }

    }

    /// <summary>

    /// 해당 이미지의 투명도를 변경한다.

    /// </summary>

    /// <param name="img"></param>

    /// <param name="opacityvalue"></param>

    /// <returns></returns>

    public Bitmap ChangeOpacity(Image img, float opacityvalue)

    {

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

        Graphics graphics = Graphics.FromImage(bmp);

        ColorMatrix colormatrix = new ColorMatrix();

        colormatrix.Matrix33 = opacityvalue;

        ImageAttributes imgAttribute = new ImageAttributes();

        imgAttribute.SetColorMatrix(colormatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);

        graphics.DrawImage(img, new Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imgAttribute);

        graphics.Dispose();

        return bmp;

    }

}