Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

In this picture, the dark of the seatback trim seems to be about the same color as the limo itself. (It is said to be Kennedy's limo.)

So, why is there so much contrast between the color of the top of the seatback and the limo on the left?

Why the rather extreme contrast between the two on the left and complete uniformity on the right?