why change the values of pixels in image increase the size of image ??

hi i want to apply stenography for text using image idea : convert the text to binary and replace last pit plane of each pixel with one bit of text but the size of image increased and when extract last bits from from new image , the result not correct.

Answer 1

[Image Analyst]

See my attached demo where I hid an image using LSB watermarking. The application to a text stream should be straightforward.