If you in 8bpp mode, your picture is 3232 pixels and have picture type 'BMP 2 colors' - then if you press 'JoyLeft' in painting window - you will jump to 'secret' menu '32x32=>16x64', where if you select 'Export' - you can save your 3232 as 1664 (right half of picture will be moved under left half). It is conveniently for BMX-animation saving. See in detail about creation of BMX-animations in chapter 'Painting'