In order to discover whether the picture is true or false we must compare it with reality. It cannot be discovered from the picture alone whether it is true or false. There is no picture which is a priori true.
The percept is the reality. It is not in propositional form. But the most immediate judgment concerning it is abstract. It is therefore essentially unlike the reality, although it must be accepted as true to that reality. Its truth consists in the fact that it is impossible to correct it, and in the fact that it only professes to consider one aspect of the percept.