Gamut Mapping Residual Encoding for Color Recovery
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Solution Overview
Problem
Gamut mapping algorithms are non-invertible due to non-linearity and clipping, resulting in irreversible color distortion and loss of information when mapping images between devices with different color gamuts, making it impossible to recover the original image from a printed gamut-mapped image on a device with a larger gamut.
Innovation Solution
Preserving the residual image, which is the data lost during gamut mapping, within the gamut-mapped image by encoding it using digital watermarking techniques, allowing the original image to be reconstructed even after printing and scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gamut mapping is applied to reproduce colors on a device with a smaller gamut, then the image can be displayed on the target device, but color information is lost and cannot be recovered
Solution Approach 1:
The patent applies preliminary action by embedding the residual image data (color information lost during gamut mapping) into the gamut-mapped image before printing. This allows the original color information to be preserved and recovered later, even after the image has been printed and scanned. The residual image is encoded using digital watermarking techniques, ensuring that the color information survives the printing and scanning process.
Solution Approach 2:
The patent uses the nested doll principle by embedding the residual image (which contains the lost color information) within the gamut-mapped image. The residual image is essentially nested inside the main image data structure, allowing both the gamut-mapped image and the original color information to coexist in a single file. This nested structure enables the recovery of original colors without adding separate external files.
2Loss of information
If a residual image is stored electronically to preserve lost color information, then the original image can be recovered, but the residual image is unavailable once the gamut-mapped electronic image has been printed
Solution Approach 1:
The patent merges the residual image data with the gamut-mapped image by embedding it using digital watermarking techniques. Instead of storing the residual image as a separate electronic file that would be lost during printing, the residual information is combined with the main image data in an inextricable way. This merged structure ensures that both the gamut-mapped image and the original color information survive the printing and scanning process together.
3Loss of information
If gamut mapping algorithms are made invertible to recover original colors, then information loss is reduced, but the algorithms become more complex and computationally intensive
Solution Approach 1:
The patent applies the taking out principle by extracting the residual image data (the difference between the original and gamut-mapped images) and embedding it separately within the gamut-mapped image. Instead of making the gamut mapping algorithm itself invertible, the patent extracts the lost information and stores it alongside the mapped image. This approach avoids the complexity of inverting non-linear gamut mapping algorithms while still enabling perfect recovery of the original colors.
Data Source
AI summary
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.