[swiftcoder]

> Would it mean that when you look at a simulation of the effects of your colorblindness, you see zero change from the unaltered view?

Ideally, yes. Although it's unlikely to match any one person's exact colour vision.

If you look at filtered images side-by-side, say from this collection on bored panda[1], to me the deutran images and the normal image are pretty much indistinguishable, while the protan image is close but slightly too green.

> Or would it mean that it looks absolutely nothing like what you see because it’s transforming the base image by clamping the input colors to what you can see, and stretching that decimated color space out over the entire range of normal sensitivity?

That's how most "colour blind filters" look in practice, yes. I don't think a lot of folks are setting up the transform correctly (or they are just straight-up using a colourblindness preview filter as if it were a colourblindness correction filter).

[1]: https://www.boredpanda.com/different-types-color-blindness-p...