Question

I am doing some image processing on a custom class representing 16 bit gray-scale images.
The intensity of the pixels is stored in a single dimension ushort array: ushort[] data
I also have the width, the height, the dpi, the stride, if necessary.

My motivation is the following: I show the results of certain operations quite fast, but the conversion from the array to the bitmapsource to the image object is too lengthy, so I was thinking of an Image object which drew its “source” directly from the array. I could thus write a method “update()” instead of doing multiple conversions.

1/ Is this possible?

2/ Would it be faster?

3/ How would I go about doing it?

The way I currently draw the image is with the following code (there’s a bit more to that, but essetially that the heart of it)

BitmapSource bmps = BitmapSource.Create(Width, Height, Dpi, Dpi, PixelFormats.Gray16, null,
                                     data, stride); 
image.Source=bmps;

Thank you!

Answer 1

Instead of using a separate array to store pixels and then creating a BitmapSource to show the results, I think it would be better using a WriteableBitmap, this way you can store pixel data (16-bit greyscale values) directly in its BackBuffer. Thus you can code something like this:

    // You create "bmp" just once and then update its content when needed
    var bmp = new WriteableBitmap(640, 480, 96, 96, PixelFormats.Gray16, null);
    var imgRect = new Int32Rect(0, 0, bmp.PixelWidth, bmp.PixelHeight);

Then you update the image:

    bmp.Lock();
    ApplySomeFilter(bmp.BackBuffer, ImageFilter.Blur);   // this is just an example ;)
    bmp.AddDirtyRect(imgRect);
    bmp.Unlock();

The ApplySomeFilter method can use unsafe code to modify pixel data of the WriteableBitmap.

---

For example, if ApplySomeFilter is defined like this:

    unsafe public void ApplySomeFilter(void* imgBuffer, ImageFilter filter)
    {
        // code that modifies pixels goes here
    }

then you can call it this way:

    ApplySomeFilter(bmp.BackBuffer.ToPointer(), ImageFilter.Blur);