AForge.Imaging.UnmanagedImage.Create C# (CSharp) Method

        public static UnmanagedImage Create( int width, int height, PixelFormat pixelFormat )
        {
            int bytesPerPixel = 0 ;

            // calculate bytes per pixel
            switch ( pixelFormat )
            {
                case PixelFormat.Format8bppIndexed:
                    bytesPerPixel = 1;
                    break;
                case PixelFormat.Format16bppGrayScale:
                    bytesPerPixel = 2;
                    break;
                case PixelFormat.Format24bppRgb:
                    bytesPerPixel = 3;
                    break;
                case PixelFormat.Format32bppRgb:
                case PixelFormat.Format32bppArgb:
                case PixelFormat.Format32bppPArgb:
                    bytesPerPixel = 4;
                    break;
                case PixelFormat.Format48bppRgb:
                    bytesPerPixel = 6;
                    break;
                case PixelFormat.Format64bppArgb:
                case PixelFormat.Format64bppPArgb:
                    bytesPerPixel = 8;
                    break;
                default:
                    throw new UnsupportedImageFormatException( "Can not create image with specified pixel format." );
            }

            // check image size
            if ( ( width <= 0 ) || ( height <= 0 ) )
            {
                throw new InvalidImagePropertiesException( "Invalid image size specified." );
            }

            // calculate stride
            int stride = width * bytesPerPixel;

            if ( stride % 4 != 0 )
            {
                stride += ( 4 - ( stride % 4 ) );
            }

            // allocate memory for the image
            IntPtr imageData = System.Runtime.InteropServices.Marshal.AllocHGlobal( stride * height );
            AForge.SystemTools.SetUnmanagedMemory( imageData, 0, stride * height );

            UnmanagedImage image = new UnmanagedImage( imageData, width, height, stride, pixelFormat );
            image.mustBeDisposed = true;

            return image;
        }

        public unsafe void ExtractBlobsImage(UnmanagedImage image, Blob blob, bool extractInOriginalSize)
        {
            if (objectLabels == null)
            {
                throw new ApplicationException("Image should be processed before to collect objects map.");
            }
            if (image.PixelFormat != PixelFormat.Format24bppRgb && image.PixelFormat != PixelFormat.Format8bppIndexed && image.PixelFormat != PixelFormat.Format32bppRgb && image.PixelFormat != PixelFormat.Format32bppArgb && image.PixelFormat != PixelFormat.Format32bppRgb && image.PixelFormat != PixelFormat.Format32bppPArgb)
            {
                throw new UnsupportedImageFormatException("Unsupported pixel format of the provided image.");
            }
            int width   = image.Width;
            int height  = image.Height;
            int stride  = image.Stride;
            int num     = System.Drawing.Image.GetPixelFormatSize(image.PixelFormat) / 8;
            int width2  = blob.Rectangle.Width;
            int height2 = blob.Rectangle.Height;
            int width3  = extractInOriginalSize ? width : width2;
            int height3 = extractInOriginalSize ? height : height2;
            int left    = blob.Rectangle.Left;
            int num2    = left + width2 - 1;
            int top     = blob.Rectangle.Top;
            int num3    = top + height2 - 1;
            int iD      = blob.ID;

            blob.Image        = UnmanagedImage.Create(width3, height3, image.PixelFormat);
            blob.OriginalSize = extractInOriginalSize;
            byte *ptr  = (byte *)image.ImageData.ToPointer() + (long)top * (long)stride + (long)left * (long)num;
            byte *ptr2 = (byte *)blob.Image.ImageData.ToPointer();
            int   num4 = top * width + left;

            if (extractInOriginalSize)
            {
                ptr2 += top * blob.Image.Stride + left * num;
            }
            int num5 = stride - width2 * num;
            int num6 = blob.Image.Stride - width2 * num;
            int num7 = width - width2;

            for (int i = top; i <= num3; i++)
            {
                int num8 = left;
                while (num8 <= num2)
                {
                    if (objectLabels[num4] == iD)
                    {
                        *ptr2 = *ptr;
                        if (num > 1)
                        {
                            ptr2[1] = ptr[1];
                            ptr2[2] = ptr[2];
                            if (num > 3)
                            {
                                ptr2[3] = ptr[3];
                            }
                        }
                    }
                    num8++;
                    num4++;
                    ptr2 += num;
                    ptr  += num;
                }
                ptr  += num5;
                ptr2 += num6;
                num4 += num7;
            }
        }