Steganography on images

This week I come across some theories about steganography on images to hide secret text. The method is to change the least signifcant bit to its reverse value. Consider a true colour image with 24 bit colour depth, altering least significant bit will cause a slight change in colour but this can hardly be detected by human eyes. How much information can an image carry ? An image might have 320 x 480 pixels and six pixels each giving out a single bit can contribute to a single ASCII text character. That is to say, an 320 x 480 image can store up to 25600 text characters which should be quite sufficient to spread secret information from one machine to another.