For a world I am working on humans managed to create a race of demi-human cat people. These people where tradionality treated as slaves/property but have in recent times been gaining some degree of freedom. Slavery has not been outlawed and there still exists large numbers of slaves many of who live in very poor conditions. However many have moved to become indentured servents, bonded labourers, 2nd class citizens or even just better treated slaves. This has created a lot of low income ghetos which are primarily dominated by the demi-cats.
What I am trying to figure out is how cats having different eyesight could be used in this story. From what I've found cats are red/green colourblind, they also have trouble seeing far away objects. Mostly I see this being used in different aspects of art or in advertising/signage. For example:
A somewhat racist sign warning you to beware of demi-cat thiefs/gangs could be done in red/green style so only a human could read it.
Billboard advertisements aimed at humans on the edge of these ghetos with offensive messages (eg. selling slaves) could be done in red/green as well.
Some demi-cat gangs/artists could make graffiti in a way that would make it hard/impossible to read for human eyes (is this possible?)
Artists making art that appears slightly differently depending on if you can see full colour. Optical illusions/hidden images in the art.
The idea behind the first two is not to make it impossible for them to read the message but rather make it easier for them to ignore. Due to cross-breading there would be a small number of demi-cats with human eyes that could understand these signs. Rumours and gossip would probably spread about what these signs say but my thoughts are a lot would not want to talk about it, and children especially might just not know they say anything.
The first part of my question is it reasonable for signs to exist in this manner but for people to not know what they say? And would making signs in this manner be an effective way of reducing unrest?
The second part of my question is how hard would it be for people to simulate what the other sees?
This society is similar technologically to our own but access to computers is extremely limited (only upper class humans would have transportable computers). From what I've found lenses can simulate or give colourblind a glimpse of full colour (EnChroma lenses). But I'm not sure how hard these would be to make and if these would be widely available to a low income environment.
On the other side from what I've found it seems computers are needed if you want to see what a colourblind person sees. I have seen a few people asking if it is possible for lenses to turn things grey scale but it seems impossible.