EPPlus/Compatibility/ImageCompat.cs

using System.IO;
using IronSoftware.Drawing;

namespace OfficeOpenXml.Compatibility
{
    internal class ImageCompat
    {
        internal static byte[] GetImageAsByteArray(AnyBitmap image)
        {
            var ms = new MemoryStream();
            if (image.GetImageFormat() == AnyBitmap.ImageFormat.Gif ||
                image.GetImageFormat() == AnyBitmap.ImageFormat.Bmp ||
                image.GetImageFormat() == AnyBitmap.ImageFormat.Png ||
                image.GetImageFormat() == AnyBitmap.ImageFormat.Tiff)
            {
                image.ExportStream(ms, image.GetImageFormat());
            }
            else
            {
                image.ExportStream(ms, AnyBitmap.ImageFormat.Jpeg);
            }

            return ms.ToArray();
        }
    }
}