Systems and methods of embedding gamut mapping information into printed images
Systems and methods preserve the information lost in gamut-mapping during marking (e.g., printing) such that the lost information survives the marking and recapture (e.g. scanning) process. Generally, an encoding method may include gamut-mapping and image for a particular device; determining a residual image; and embedding the information needed to recover the residual image within the pixels of the gamut-mapped image. Generally, a decoding method may include extracting the embedded information from the image; and using the residual image to restore the gamut-mapped image to the original image.
1. A method of encoding gamut information into a marked image, comprising:
transforming an image with a first gamut;
mapping the transformed image to a second gamut to obtain a second-gamut image;
determining a first residual image between the image with a first gamut and the transformed image;
determining a second residual image between the transformed image and the second-gamut image; and
separately encoding the first and second residual images within the second-gamut image, wherein
the encoded first and second residual images may be decoded from a marked copy of the second-gamut image.
2. The method of claim 1 , wherein determining the second residual image between the transformed image and the second-gamut image comprises determining a difference between the transformed image and the second-gamut image.
3. The method of claim 1 , further comprising compressing the second residual image, wherein encoding the second residual image within the second-gamut image comprises encoding the compressed second residual image within the second-gamut image.
4. The method of claim 1 , further comprising converting the second-gamut image to an output device color space characterization.
5. The method of claim 1 , wherein encoding the second residual image within the second-gamut image comprises encoding the second residual image within the second-gamut image as a digital watermark.
6. The method of claim 1 , wherein encoding the second residual image within the second-gamut image comprises encoding a pointer within the second-gamut image that points to the second residual image stored electronically.
7. A storage medium storing a set of program instructions executable on a data processing device and usable for performing the method recited in claim 1 .
8. A method of decoding gamut information from a captured marked image, comprising:
decoding, from the captured marked image, a first residual image between an image with a first gamut and a transformed image;
decoding, from the captured marked image, a second residual image between the transformed image and a second-gamut image; and
adding the decoded first and second residual images to the captured marked image, wherein
the first gamut is larger than a gamut of the second-gamut image.
9. The method of claim 8 , further comprising decompressing the second residual image.
10. The method of claim 8 , further comprising converting the captured marked image to a predetermined color space characterization.
11. The method of claim 8 , further comprising reversing an image transform.
12. The method of claim 11 , wherein reversing an image transform comprises reversing the image transform after adding the decoded second residual image to the captured image.
13. The method of claim 8 , wherein decoding the second residual image from the captured marked image comprises decoding a digital watermark within the captured marked image.
14. The method of claim 8 , wherein:
decoding the second residual image from the captured marked image comprises decoding a pointer within the captured marked image that points to the second residual image stored electronically; and
the method further comprises locating the residual image electronically.
15. A storage medium storing a set of program instructions executable on a data processing device and usable for performing the method recited in claim 8 .
16. A system for encoding gamut information into a marked image, comprising:
an image data source that provides an image with a first gamut;
a controller that:
transforms the image with a first gamut;
maps the transformed image to a second gamut to obtain a second-gamut image;
determines a first residual image between the image with a first gamut and the transformed image;
determines a second residual image between the transformed image and the second-gamut image; and
separately encodes the first and second residual images within the second-gamut image; and
a data storage device that at least temporarily stores the second-gamut image, wherein the encoded first and second residual images may be decoded from a marked copy of the second-gamut image.
17. A system that decodes gamut information from a captured marked image, comprising:
an image data source that provides a captured marked image; and
a controller that:
decodes, from the captured marked image, a first residual image between an image with a first gamut and a transformed image;
decodes, from the captured marked image, a second residual image between the transformed image and a second-gamut image; and
adds the decoded first and second residual images to the captured image, wherein
the first gamut is larger than a gamut of the second-gamut image.