Blazor.ImageToAscii is a Blazor WebAssembly app that transforms an image to an ASCII map, using darkerst to lighter character sets. You can find working sample of the app at https://i2t.azurewebsites.net/
The actual engine is a .NET Standard library (Image2Text.Core) that uses ImageSharp to read the image and transform each byte to a character.
The library offers more capabilities than what the sample contains (e.g. change the size of the image, use different character sets etc.), so this is actually work in progress!