CSharp/ImageGetBuffer.cs

/*=========================================================================
*
*  Copyright Insight Software Consortium
*
*  Licensed under the Apache License, Version 2.0 (the "License");
*  you may not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*         http://www.apache.org/licenses/LICENSE-2.0.txt
*
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*
*=========================================================================*/

using System;
using System.Runtime.InteropServices;

using itk.simple;
using PixelId = itk.simple.PixelIDValueEnum;

namespace itk.simple.examples {
  public class Program {
    static void Main(string[] args) {

      if (args.Length < 1) {
        Console.WriteLine("Usage: SimpleGaussian <input>");
        return;
      }

      // Read input image
      itk.simple.Image input = SimpleITK.ReadImage(args[0]);

      // Cast to we know the the pixel type
      input = SimpleITK.Cast(input, PixelId.sitkFloat32);

      // calculate the nubmer of pixels
      VectorUInt32 size = input.GetSize();
      int len = 1;
      for (int dim = 0; dim < input.GetDimension(); dim++) {
        len *= (int)size[dim];
      }
      IntPtr buffer = input.GetBufferAsFloat();

      // There are two ways to access the buffer:

      // (1) Access the underlying buffer as a pointer in an "unsafe" block
      // (note that in C# "unsafe" simply means that the compiler can not
      // perform full type checking), and requires the -unsafe compiler flag
      // unsafe {
      //   float* bufferPtr = (float*)buffer.ToPointer();

      //   // Now the byte pointer can be accessed as per Brad's email
      //   // (of course this example is only a 2d single channel image):
      //   // This is a 1-D array but can be access as a 3-D. Given an
      //   // image of size [xS,yS,zS], you can access the image at
      //   // index [x,y,z] as you wish by image[x+y*xS+z*xS*yS],
      //   // so x is the fastest axis and z is the slowest.
      //   for (int j = 0; j < size[1]; j++) {
      //     for (int i = 0; i < size[0]; i++) {
      //       float pixel = bufferPtr[i + j*size[1]];
      //       // Do something with pixel here
      //     }
      //   }
      // }

      // (2) Copy the buffer to a "safe" array (i.e. a fully typed array)
      // (note that this means memory is duplicated)
      float[] bufferAsArray = new float[len]; // Allocates new memory the size of input
      Marshal.Copy(buffer, bufferAsArray, 0, len);
      double total = 0.0;
      for (int j = 0; j < size[1]; j++) {
        for (int i = 0; i < size[0]; i++) {
          float pixel = bufferAsArray[i + j*size[1]];
          total += pixel;
        }
      }
      Console.WriteLine("Pixel value total: {0}", total);

    }
  }
}