AForge.Imaging.Filters.Shrink.CalculateNewImageSize C# (CSharp) Method

        protected override System.Drawing.Size CalculateNewImageSize( UnmanagedImage sourceData )
        {
            // get source image size
            int width = sourceData.Width;
            int height = sourceData.Height;
            int offset = sourceData.Stride -
                ( ( sourceData.PixelFormat == PixelFormat.Format8bppIndexed ) ? width : width * 3 );

            // color to remove
            byte r = colorToRemove.R;
            byte g = colorToRemove.G;
            byte b = colorToRemove.B;

            minX = width;
            minY = height;
            int maxX = 0;
            int maxY = 0;

            // find rectangle which contains something except color to remove
            unsafe
            {
                byte* src = (byte*) sourceData.ImageData.ToPointer( );

                if ( sourceData.PixelFormat == PixelFormat.Format8bppIndexed )
                {
                    // grayscale
                    for ( int y = 0; y < height; y++ )
                    {
                        for ( int x = 0; x < width; x++, src++ )
                        {
                            if ( *src != g )
                            {
                                if ( x < minX )
                                    minX = x;
                                if ( x > maxX )
                                    maxX = x;
                                if ( y < minY )
                                    minY = y;
                                if ( y > maxY )
                                    maxY = y;
                            }
                        }
                        src += offset;
                    }
                }
                else
                {
                    // RGB
                    for ( int y = 0; y < height; y++ )
                    {
                        for ( int x = 0; x < width; x++, src += 3 )
                        {
                            if (
                                ( src[RGB.R] != r ) ||
                                ( src[RGB.G] != g ) ||
                                ( src[RGB.B] != b ) )
                            {
                                if ( x < minX )
                                    minX = x;
                                if ( x > maxX )
                                    maxX = x;
                                if ( y < minY )
                                    minY = y;
                                if ( y > maxY )
                                    maxY = y;
                            }
                        }
                        src += offset;
                    }
                }
            }

            // check
            if ( ( minX == width ) && ( minY == height ) && ( maxX == 0 ) && ( maxY == 0 ) )
            {
                minX = minY = 0;
            }

            return new Size( maxX - minX + 1, maxY - minY + 1 );
        }