Converting BitmapImage to Bitmap and vice versa

Question

I have BitmapImage in C#. I need to do operations on image. For example grayscaling, adding text on image, etc.

I have found function in stackoverflow for grayscaling which accepts Bitmap and returns Bitmap.

So I need to convert BitmapImage to Bitmap, do operation and convert back.

How can I do this? Is this best way?

Answer 1

There is no need to use foreign libraries.

Convert a BitmapImage to Bitmap:

private Bitmap BitmapImage2Bitmap(BitmapImage bitmapImage)
{
    // BitmapImage bitmapImage = new BitmapImage(new Uri("../Images/test.png", UriKind.Relative));

    using(MemoryStream outStream = new MemoryStream())
    {
        BitmapEncoder enc = new BmpBitmapEncoder();
        enc.Frames.Add(BitmapFrame.Create(bitmapImage));
        enc.Save(outStream);
        System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(outStream);

        return new Bitmap(bitmap);
    }
}

To convert the Bitmap back to a BitmapImage:

[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern bool DeleteObject(IntPtr hObject);

private BitmapImage Bitmap2BitmapImage(Bitmap bitmap)
{
    IntPtr hBitmap = bitmap.GetHbitmap();
    BitmapImage retval;

    try
    {
        retval = (BitmapImage)Imaging.CreateBitmapSourceFromHBitmap(
                     hBitmap,
                     IntPtr.Zero,
                     Int32Rect.Empty,
                     BitmapSizeOptions.FromEmptyOptions());
    }
    finally
    {
        DeleteObject(hBitmap);
    }

    return retval;
}

Answer 2

Here's an extension method for converting a Bitmap to BitmapImage.

    public static BitmapImage ToBitmapImage(this Bitmap bitmap)
    {
        using (var memory = new MemoryStream())
        {
            bitmap.Save(memory, ImageFormat.Png);
            memory.Position = 0;

            var bitmapImage = new BitmapImage();
            bitmapImage.BeginInit();
            bitmapImage.StreamSource = memory;
            bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
            bitmapImage.EndInit();
            bitmapImage.Freeze();

            return bitmapImage;
        }
    }

Answer 3

If you just need to go from BitmapImage to Bitmap it's quite easy,

private Bitmap BitmapImage2Bitmap(BitmapImage bitmapImage)
    {
        return new Bitmap(bitmapImage.StreamSource);
    }