Recently, several steganographic algorithms for two-color binary images have been proposed[16, 1, 14, 2]. In this paper, we propose steganographic algorithms which embeds a secret message into bitmap images and palette-based images. To embed a message, the suggested algorithm divides a bitmap image into bit-plane images from LSB-plane to MSB-plane for each pixel, and considers each bit-plane image as a binary one. The algorithm splits each bit-plane image into m × n blocks, and embeds a r-bit(r = [log2(mn + 1)] - 1) message into the block. And our schemes embed a message to every bit-plane from LSB to MSB to maximize the amount of embedded message and to minimize the degradation. The schemes change at most two pixels in each block. Therefore, the maximal color changes of the new algorithm are much smaller than other bit-plane embedding schemes' such as the sequential substitution schemes [10, 7, 11].