| 摘要 |
<p>A signal component (e.g., a period signal component such as a sinusoid) is added (210) to an original color image to form a modified color image, with the goal of embedding the signal in the image so that it is imperceptible to a human viewer. A comparing operation (240) uses a model of human perception to measure the perceptual difference between the original and modified images, identifying local areas of the modified image where the signal difference exceeds a threshold, indicating that the signal is perceptible to a human viewer. Using the perceptual difference measurement data; the signal is attenuated in the identified local areas that indicate a perceptually unacceptable difference, and this modified signal component is then added (210) to the original color image in a next iteration. Perceptual difference measurement and signal attenuation are iterated until the comparison operation determines that the signal difference is perceptually acceptable. The technique takes advantage of the fact that, although the spatial frequencies of the embedded signals are well within the range of spatial frequencies to which humans are normally quite sensitive in the luminance (black-white) vision channel, this sensitivity does not extend to the color vision bands. In an illustrated embodiment, a set of sinusoidal signals that form a grid are added to the color image; location (i.e., decoding) of the sinusoids, which does not require the original color image, allows computing a geometric mapping from an image with the embedded signals to the original image. <IMAGE></p> |
