Сжатие Bitmap и класс System.IO.Compression.GZipStream

Rectangle screenBounds = Screen.GetBounds(Point.Empty);
            Bitmap bitmap = new Bitmap(screenBounds.Width, screenBounds.Height, PixelFormat.Format16bppRgb565);
            using (Graphics graphics = Graphics.FromImage(bitmap))
            {
                graphics.CopyFromScreen(Point.Empty, Point.Empty, screenBounds.Size);
            }
            byte[] compressed = null;
            using (MemoryStream bitmapStream = new MemoryStream())
            {
                bitmap.Save(bitmapStream, ImageFormat.Bmp);               
                using (MemoryStream outStream = new MemoryStream())
                {
                    using (GZipStream tinyStream = new GZipStream(outStream, CompressionMode.Compress))
                    {
                        bitmapStream.CopyTo(tinyStream);
                        compressed = outStream.ToArray();
                    }
                }
            }

            Rectangle screenBounds = Screen.GetBounds( Point.Empty );
 
            using( var bitmap = new Bitmap( screenBounds.Width, screenBounds.Height, PixelFormat.Format16bppRgb565 ) )
            {
                using( Graphics graphics = Graphics.FromImage( bitmap ) )
                    graphics.CopyFromScreen( Point.Empty, Point.Empty, screenBounds.Size );
                // original
                bitmap.Save( "source.bmp", ImageFormat.Bmp );
                // zip
                using( var file = new FileStream( "bmp.gzip", FileMode.Create, FileAccess.Write ) )
                using( var gzip = new GZipStream( file, CompressionMode.Compress ) )
                    bitmap.Save( gzip, ImageFormat.Bmp );
            }
            // unzip
            using( var fRead = new FileStream( "bmp.gzip", FileMode.Open, FileAccess.Read ) )
            using( var fWrite = new FileStream( "bmp.bmp", FileMode.Create, FileAccess.Write ) )
            using( var gzip = new GZipStream( fRead, CompressionMode.Decompress ) )
            {
                var buff = new byte[4096];
                int readed = 0;
 
                while( (readed = gzip.Read( buff, 0, buff.Length )) != 0 )
                    fWrite.Write( buff, 0, readed );
            }

        private byte[] CompressBitmap( Bitmap bmp )
        {
            using ( var zipped = new MemoryStream( ) )
            {
                using( var gzip = new GZipStream( zipped, CompressionMode.Compress ) )
                    bmp.Save( gzip, ImageFormat.Bmp );
 
                return zipped.ToArray( );
            }
        }

            Rectangle screenBounds = Screen.GetBounds( Point.Empty );
            byte[] zipped = null;
 
            using( var bitmap = new Bitmap( screenBounds.Width, screenBounds.Height, PixelFormat.Format16bppRgb565 ) )
            {
                using( Graphics graphics = Graphics.FromImage( bitmap ) )
                    graphics.CopyFromScreen( Point.Empty, Point.Empty, screenBounds.Size );
 
                zipped = this.CompressBitmap( bitmap );
            }
            // unzip
            byte[] source = null;
            using( var fRead = new MemoryStream( zipped ) )
            using( var fWrite = new MemoryStream() )
            using( var gzip = new GZipStream( fRead, CompressionMode.Decompress ) )
            {
                var buffer = new byte[4096];
                int readed = 0;
 
                while( (readed = gzip.Read( buffer, 0, buffer.Length )) != 0 )
                    fWrite.Write( buffer, 0, readed );
 
                source = fWrite.ToArray();
            }