Create Bitmap from a byte array of pixel data

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  1. Its safe if you marshal.copy data rather than setting scan0 (directly or via that overload of BitMap()). You don’t want to keep managed objects pinned, this will constrain the garbage collector.
  2. If you copy, perfectly safe.
  3. The input array is managed and can be moved by the GC, scan0 is an unmanaged pointer that would get out of date if the array moved. The Bitmap object itself is managed but sets the scan0 pointer in Windows via a handle.
  4. ImageLockMode.UserInputBuffer is? Apparently it can be passed to LockBits, maybe it tells Bitmap() to copy the input array data.

Example code to create a greyscale bitmap from array:

    var b = new Bitmap(Width, Height, PixelFormat.Format8bppIndexed);

    ColorPalette ncp = b.Palette;
    for (int i = 0; i < 256; i++)
        ncp.Entries[i] = Color.FromArgb(255, i, i, i);
    b.Palette = ncp;

    var BoundsRect = new Rectangle(0, 0, Width, Height);
    BitmapData bmpData = b.LockBits(BoundsRect,
                                    ImageLockMode.WriteOnly,
                                    b.PixelFormat);

    IntPtr ptr = bmpData.Scan0;

    int bytes = bmpData.Stride*b.Height;
    var rgbValues = new byte[bytes];

    // fill in rgbValues, e.g. with a for loop over an input array

    Marshal.Copy(rgbValues, 0, ptr, bytes);
    b.UnlockBits(bmpData);
    return b;

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