How to set color of transparent areas?

[SoftCircuits]

When converting an image from a format that supports transparency, like PNG, to a format that doesn't support transparency, like JPG, is there any way to specify the color of the transparent pixels?

I have the following method that resizes an image. It converts from PNG to JPG. The result is an entirely black image. I think it's setting the transparent pixels to black. I'd much prefer to set them to white.

    public byte[] Resize(uint maxX, uint maxY, ResizeOptions options = ResizeOptions.None)
    {
        uint oldWidth = Image.Width;
        uint oldHeight = Image.Height;

        // Swap max dimensions if needed
        if (options.HasFlag(ResizeOptions.AllowEitherOrientation) && (maxX >= maxY) != (oldWidth >= oldHeight))
            (maxY, maxX) = (maxX, maxY);

        IMagickImage image = Image.Clone();
        image.Resize(maxX, maxY);
        image.Format = MagickFormat.Jpeg;
        image.Quality = 80;
        using MemoryStream memoryStream = new();
        image.Write(memoryStream);
        return memoryStream.ToArray();
    }

[dlemstra]

Have you tried to use Image.ColorAlpha?