Converting an array of Pixels to an image in C#

Question

I have an array of int pixels in my C# program and I want to convert it into an image. The problem is I am converting Java source code for a program into equiva

Answer 1

You can use Bitmap.LockBits to obtain the bitmap data that you can then manipulate directly, rather than via SetPixel. (How to use LockBits)

Answer 2

Well, I'm assuming each int is the composite ARGB value? If there isn't an easy option, then LockBits might be worth looking at - it'll be a lot quicker than SetPixel, but is more complex. You'll also have to make sure you know how the int is composed (ARGB? RGBA?). I'll try to see if there is a more obvious option...

Answer 3

I would recommend using LockBits but a slower SetPixel based algorithm might look something like

// width - how many int's per row        
// array - array of integers
Bitmap createImage(int width, int[] array)
{            
  int height = array.Length / width;
  Bitmap bmp = new Bitmap(width, height);
  for (int y = 0; y < height; y++)
  {
    for (int x = 0; x < array.Length; x += width)
    {
      bmp.SetPixel(x, y, Color.FromArgb(array[i]));
    }
  }
  return bmp;
}

Answer 4

Using WPF, you can create a bitmap (image) directly from your array. You can then encode this image or display it or play with it:

int width = 200;
int height = 200;

//
// Here is the pixel format of your data, set it to the proper value for your data
//
PixelFormat pf = PixelFormats.Bgr32;
int rawStride = (width * pf.BitsPerPixel + 7) / 8;

//
// Here is your raw data
//
int[] rawImage = new int[rawStride * height / 4];


//
// Create the BitmapSource
//
BitmapSource bitmap = BitmapSource.Create(
    width, height,
    96, 96, pf, null,
    rawImage, rawStride);

Answer 5

MemoryImageSource's constructor's 3rd argument is an array of ints composed of argb values in that order

The example in that page creates such an array by;

pix[index++] = (255 << 24) | (red << 16) | blue;

You need to decompose that integer array to a byte array (shift operator would be useful), but it should be in bgr order, for LockBits method to work.

Answer 6

I like the WPF option already presented, but here it is using LockBits and Bitmap:

        // get the raw image data
        int width, height;
        int[] data = GetData(out width, out height);

        // create a bitmap and manipulate it
        Bitmap bmp = new Bitmap(width,height, PixelFormat.Format32bppArgb);
        BitmapData bits = bmp.LockBits(new Rectangle(0, 0, width, height),
            ImageLockMode.ReadWrite, bmp.PixelFormat);
        unsafe
        {
            for (int y = 0; y < height; y++)
            {
                int* row = (int*)((byte*)bits.Scan0 + (y * bits.Stride));
                for (int x = 0; x < width; x++)
                {
                    row[x] = data[y * width + x];
                }
            }
        }
        bmp.UnlockBits(bits);

With (as test data):

    public static int[] GetData(out int width, out int height)
    {
        // diagonal gradient over a rectangle
        width = 127;
        height = 128;
        int[] data =  new int[width * height];
        for (int x = 0; x < width; x++)
        {
            for (int y = 0; y < height; y++)
            {
                int val = x + y;
                data[y * width + x] = 0xFF << 24 | (val << 16) | (val << 8) | val;
            }
        }
        return data;
    }