How to Convert 2-D array into Image in c#

Question

I have a 2D array of integers in c#.

Each entry in the 2-D array correspond to a pixel value

How can i make this 2-D array into an image file (in C#)

Thanks

Answer 1

Here is a very fast, albeit unsafe, way of doing it:

[Edit] This example took 0.035 ms

// Create 2D array of integers
int width = 320;
int height = 240;
int stride = width * 4;
int[,] integers = new int[width,height];

// Fill array with random values
Random random = new Random();
for (int x = 0; x < width; ++x)
{
    for (int y = 0; y < height; ++y)
    {
        byte[] bgra = new byte[] { (byte)random.Next(255), (byte)random.Next(255), (byte)random.Next(255), 255 };
        integers[x, y] = BitConverter.ToInt32(bgra, 0);
    }
}

// Copy into bitmap
Bitmap bitmap;
unsafe
{
    fixed (int* intPtr = &integers[0,0])
    {
        bitmap = new Bitmap(width, height, stride, PixelFormat.Format32bppRgb, new IntPtr(intPtr));
    }
}

and the result:

Answer 2

If you have the need for speed look at my Kinect sample. Basically it creates a memory area and uses an unsafe pointer to generate an Int32 array towards the memory. A BitmapSource object is used to map a bitmap (image) directly onto the same area. This particular example also uses unmanaged memory to make it compatible with P/Invoke.

This blogpost describes the difference in performance of using unsafe. Part from that have a look at:

• http://www.bytemycode.com/snippets/snippet/412/
• http://www.jmsoftware.co.uk/blog/c-snippet-for-accessing-bitmap-data-with-unsafe-code
• http://www.vcskicks.com/fast-image-processing.php

Note that you can just as well make a Int32[]-pointer instead of the examples which uses Byte[]-pointer.

Answer 3

If speed is not a concern - Bitmap + SetPixel and than save to a file: http://msdn.microsoft.com/en-us/library/system.drawing.bitmap.setpixel.aspx

Answer 4

Bitmap.LockBits should work, if you're wanting a WinForms image.

Answer 5

Would projecting the array into a base64 string for streaming into a Bitmap be slow too?