How does "Postcard from Kashmir" reveal the natural beauty of Kashmir on one level and its grim social reality on the other?

The speaker realizes that the little postcard of Kashmir he holds in his hands presents a somewhat idealized portrait of his home province. But he's so in love with the place that he really doesn't seem to mind. He knows full well that when he returns home, the colors won't be so brilliant as those on the postcard, nor the waters of the Jhellum quite so clean or ultramarine.
But none of that really matters. For the speaker's memories of Kashmir are like a giant photographic negative, black and white, still waiting to be developed. In other words, the speaker realizes that once he returns home, he must somehow recreate in his own life the immense color and beauty of the pretty little postcard. He must try and make the reality conform to the ideal as much as possible.