This challenge was fairly simple, but had one or two complications.
The first step was parsing the image. Before I could script it, I opened up the image in GIMP to have a look at spacing. As it turned out, each braille block was 30 pixels wide, but the heights weren't consistent. On odd rows it was 43 pixels high, and even rows were 44 pixels high. There were 33 blocks to a row, and 57 rows in the image.