An image compression apparatus transforms original image data partitioned into first blocks, each of which is composed of a plurality of pixels, to reduced-image data composed of a smaller number of pixels than that of the original image data. The housing includes an open base frame, which is bonded with two PC boards at top and bottom sides thereof and is provided with two receiving open chambers defined between the open base frame and the two PC boards for accommodating different cards. In operation, the blade pitch drive is controlled by only one of the power control modules.