AForge.Imaging.Formats.PNMCodec.ReadP5Image C# (CSharp) Метод

        private unsafe Bitmap ReadP5Image( Stream stream, int width, int height, int maxValue )
        {
            double scalingFactor = (double) 255 / maxValue;

            // create new bitmap and lock it
            Bitmap image = Tools.CreateGrayscaleImage( width, height );
            BitmapData imageData = image.LockBits( new Rectangle( 0, 0, width, height ),
                ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed );

            int stride = imageData.Stride;
            byte* ptr = (byte*) imageData.Scan0.ToPointer( );

            // prepare a buffer for one line
            byte[] line = new byte[width];

            int totalBytesRead = 0, bytesRead = 0;

            // load all rows
            for ( int y = 0; y < height; y++ )
            {
                totalBytesRead = 0;
                bytesRead = 0;

                // load next line
                while ( totalBytesRead != width )
                {
                    bytesRead = stream.Read( line, totalBytesRead, width - totalBytesRead );

                    if ( bytesRead == 0 )
                    {
                        // if we've reached the end before complete image is loaded, then there should
                        // be something wrong
                        throw new Exception( );
                    }

                    totalBytesRead += bytesRead;
                }

                // fill next image row
                byte* row = ptr + stride * y;

                for ( int x = 0; x < width; x++, row++ )
                {
                    *row = (byte) ( scalingFactor * line[x] );
                }
            }

            // unlock image and return it
            image.UnlockBits( imageData );
            return image;
        }