you have to ask yourself, how is it that a person could look at that picture/caption and NOT think it is racist. it's actually pretty simple. here's how:
1) look at the picture (this is the easiest part).
2) read the caption (this at least requires some degree of literacy).
3) see a big word, and ignore it (in this particular case, the caption then magically changes to "Is a crime against American values - Repeal Loving v. Virginia").
3½) see a reference to a Supreme Court case you know nothing about. Ignore this as well.
4) after revising the caption in your mind in step 3-3½ (thus warping reality to your fiercely determined will), you truthfully state that there is nothing racist about this picture/caption.
to be fair, that's not the way most reasonable people would tackle this question, so I'll demonstrate how that works here as well:
1) look at the picture (this is the easiest part).
2) read the caption (this at least requires some degree of literacy).
3) see a big word, and realize that you don't understand what it means (miscegenation is the mixing of racial groups - NOTE: this general definition took less than 10 seconds to find using a quick Google search).
3½) incorporate the meaning of the previously mentioned "big word" into the rest of the caption to gain an understanding of what is being said (in this particular case, the caption then magically changes to "The mixing of racial groups is a crime against American values - Repeal Loving v. Virginia").
3¾) *OPTIONAL STEP* at this point, you already have enough information to make a valid determination as to the racial intent of the picture, so you can move on to step 4 if you like. if you prefer to be really thorough though, you could look up the Loving v. Virginia case as well (where you would find that this is the case that ended all race-based marriage restrictions in this country)
4) after revising the caption in your mind in step 3-3¾ (thus coming to an understanding of the reality of the matter), you truthfully come to the conclusion that this picture, and it's corresponding caption are, in fact, reallyfuckingracist.