These three images are actually just the same image with different color palettes.
Mike arranged the colors in such a way that he could seamlessly cross fade between all three states.
This image is the last stage of the title sequence. After the titles have finished appearing the grayscale image is replaced with this image, which then fades into the colored version.
Most objects in the game only use two bit planes (equalling 4 colors) and are then shifted to different parts of the palette to create differently colored opponent planes or obstacles.
The player object is special. It uses the same bit planes that the opponents use, but add an additional bit plane, bumping up the number of bitplanes to three (equalling 8 colors). The benefit of this is that the player's plane looks much better, re-uses the same images that the opponents use, but only requires the additional bit plane for the one size, because the player never moves backwards/forwards in the screen. Really clever.
