Full Idea
Things like colors, taste etc. are correctly considered not as qualities of things but as mere alterations of our subject, which can even be different in different people.
Clarification
'The subject' is the experiencing person
Gist of Idea
Colours and tastes are not qualities of things, but alterations of the subject
Source
Immanuel Kant (Critique of Pure Reason [1781], B045/A29)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.161
A Reaction
This acceptance of the category of 'secondary' qualities shows that Kant is not totally daft about reality. He 'considers them as' alterations in the subject, but how does he view primary qualities? Not, I think, as features of the noumenon.