How can I create an "inner bevel" effect on text?

[rambouillet]

I'm trying to create the following effect with some text:

Here's a method I wrote to create the text so far:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Drawing.Processing;
using SixLabors.ImageSharp.Formats.Png;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.PixelFormats;

public static void CreateTextPng(string SavePath, int Width, string Text)
{
    var TheFont = new Font(SystemFonts.Find("Times New Roman"), 40, FontStyle.Bold);
    var Size = TextMeasurer.Measure(Text, new RendererOptions(TheFont) { WrappingWidth = Width });
    using (var TheImage = new Image<Rgba32>(Width, (int)Math.Round(Size.Height)))
    {
        TheImage.Mutate(delegate (IImageProcessingContext Processor)
        {
            var textGraphicsOptions = new TextGraphicsOptions(new GraphicsOptions(), new TextOptions
            {
                HorizontalAlignment = HorizontalAlignment.Center,
                VerticalAlignment = VerticalAlignment.Center,
                WrapTextWidth = TheImage.Width
            });
            Processor.DrawText(textGraphicsOptions, Text, TheFont, Color.Yellow, new PointF(0, TheImage.Height / 2));
            //
            //I think this is where the code to create the "inner bevel" effect would go, but I don't know what to put here...
            //
        });
        TheImage.SaveAsPng(SavePath, new PngEncoder { CompressionLevel = PngCompressionLevel.BestCompression });
    }
}

And here is the method call:

CreateTextPng("C:/dev/textexample.png", 400, "Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch");

Can this bevel effect be done with ImageSharp at all? Any help would be appreciated!

[JimBobSquarePants]

@rambouillet There's no built in methods to do this I'm afraid.

I've done a little bit of research though into how this would be achieved.

Bevel effects can be achieved by the application of Bump or Normal Maps to a 2D image. You'd need an emboss convolution filter that can be generated and rotated by an arbitrary angle that is used to populate the map.

This library which is based on an old version of ImageSharp contains code to generate maps. It shouldn't be too hard to port that using an improved emboss filter.

I'm not 100% sure how the map is then applied to the image though to alter the brightness but this link seems to contain further information.
http://www.inf.ed.ac.uk/teaching/courses/cg/lectures/cg12_2012.pdf

P.S. Love that book!