Methods and apparatus for hiding data in halftone images

摘要

We propose modifying the error-diffusion method for transforming a grey-scale image into a halftone image, so that binary data is hidden in the resulting halftone image. Simultaneously, a second halftone image is generated by error diffusion, not storing the hidden data. The hidden binary data is typically a binary image, and the dark regions of this binary image can be seen when the two halftone images are overlaid.