C# - fast byte array to bitmap conversion with Graphics to add text

Question

I'm converting byte[] to bitmap using this function:

public static Bitmap ArrayToBitmap(
    byte[] bytes, int width, int height, PixelFormat pixelFormat)
    {
        var image = new Bitmap(width, height, pixelFormat);
        var imageData = image.LockBits(new Rectangle(0, 0, image.Width, image.Height),
                          ImageLockMode.ReadWrite, pixelFormat);
        try
        {
            Marshal.Copy(bytes, 0, imageData.Scan0, bytes.Length);
        }
        finally
        {
            image.UnlockBits(imageData);
        }
        return image;
    }

this works great. If I convert the result back to byte[] and output it as ByteArrayContent I see the resulting image in the browser. My source file is a PNG and for pixelFormat parameter I can use either Format16bppArgb1555 or Format32bppArgb, both work if I convert back from bitmap to byte[].

However when I'm trying to feed the converted bitmap into:

using (var g = Graphics.FromImage(bitmap))
{
    // add custom text to image
}

For Format16bppArgb1555 I get an "out of memory" exception on the "using" line when it tries to create Graphics object using .FromImage(). The exception reads:

Message = "Out of memory."
Source = "System.Drawing"

and for Format32bppArgb the result is a corrupted image with my custom text on top of it.

Is it possible to get one of them to work? Alternatively, is there a fast way of converting byte[] to image, adding text and converting result back to byte[] again?

I tried using Magick.NET (Q8-x64) which enabled me to do all of the above only it was really slow. Slower than the regular method:

1. convert byte[] to MemoryStream
2. get bitmap from Image.FromStream()
3. add text
4. bitmap.Save() to MemoryStream
5. memoryStream.ToArray()

Edit 2: probably worth to mention that the original PNG images comes from HTML5 Canvas .ToDataUrl() method.