If you get no text, just boxes, try another font.
Colors are entered in RRGGBB or RRGGBBAA format, where RR, GG and BB are the red, green and blue components, respectively, from 00 to FF, and AA is the alpha channel (00 is opaque, 7F is totally transparent). If AA is omitted, it will be opaque.
Size is the size of the letters in points. Height is the size of the image. If your text is truncated on the top or bottom, increase height or decrease size.
Angle is the rotation in degrees, counterclockwise.
Square makes the image square, useful for icons.