Colors are also different to different species (say, in dogs) because of the eyes' lenses. They reflect light differently. Is red really "red?" or is it that we see it as red? We just see it that way. Who knows what it really looks like?
Your question is a great question , who knows what it really looks like ! Well , who knows what it really feels like ?
We all have senses , we all can physically feel the shape of something . So from this we can conclude that what we feel is real . So then we extend this question , Is what we hear what we really hear ? Well, if what we hear wasn't real , we'd never be able to communicate verbally .So that is touch and hearing covered , we can conclude they are real .Smell , we can all agree xxxx stinks , so that is real .
We all can pick red apples out of a basket of mixed apple , so what we see must be real .
Evidence suggests colour exists independent of sight , the shadow I have mentioned already .The second piece of evidence is movement , things would Doppler Shift when moved at any velocity because the difference between blue and red is so miniscule . Natural sunlight is explained as white light , a mixture of frequencies but white is poor semantics because the light traversing through space is observed as clear and it is also transparent . Ligtht is never opaque traversing through space although sometimes it can be translucent such as a rainbow and blinding opaque such as lightning .
In example if I moved away from you , if I was reflecting wave-lengths , these wave-lengths would become stretched . If I was reflecting any sort of wave-lengths , a simple TV antenna or other device could detect this.
Science can emit a wave-length of red , blue etc and detect these signals , converting the signal into what you see , blue or red etc on a monitor . However , you can point the largest satellite dish in the world at a blue wall and you will detect nothing . The only reason for this , is that the blue of the wall is dependent to the wall and not a wave-length .
The scientists mistake of the past was to think because of the prism , that colour was light dependent . So in other words , a red apple in the dark is still red and the fact that no wave-length can be detected even in the light , shows the independent nature of colour .