System and method for spot color correction
Patent No. US8743421 (titled "System and method for spot color correction") on Jul 15, 2012. The application was issued on Jun 3, 2014.
What is this patent about?
'421 is related to the field of pre-press workflow systems used in digital printing. Specifically, it addresses the problem of accurately reproducing spot colors in printed documents when the printing device cannot use the actual spot color ink, and instead must simulate it using process colors (CMYK). The background acknowledges the challenges in matching colors between computer displays and printed output due to differing color gamuts and environmental factors affecting print results.
The underlying idea behind '421 is to provide a user-friendly method for correcting spot color inaccuracies by generating a printed swatch page containing a range of color variations around the original spot color. The user visually selects the tile that best matches the desired output, and then inputs the numerical identifier of that tile into the workflow application. This allows the system to adjust the color values in the document to better approximate the intended spot color.
The claims of '421 focus on a method, performed within a workflow printing system, that involves identifying spot colors in a page description language (PDL) document, printing a swatch page for each spot color needing correction, where each swatch page contains a matrix of color tiles with unique numerical identifiers, selecting a color tile that visually matches the desired output, and then inputting the corresponding numerical value into the workflow application to alter the PDL document and record the color change.
In practice, the invention analyzes a PDL file (e.g., PostScript or PCL) to identify spot colors. For each spot color selected for correction, the system generates a swatch page with a matrix of color tiles. These tiles represent variations in hue, saturation, and value (HSV) around the original spot color. Each tile is assigned a unique numerical identifier based on its HSV values. The user visually compares the printed swatch page to a reference color and selects the tile that provides the best match.
The selected tile's numerical identifier is then entered into the workflow application. The application uses this identifier to determine the corresponding HSV (or other color space) values and modifies the PDL file to use these new values for the spot color. This process effectively replaces the original spot color definition with a process color approximation that has been visually validated by the user. This differs from prior approaches that rely on trial-and-error adjustments or mathematical color conversions without user feedback.
How does this patent fit in bigger picture?
Technical Landscape
In the early 2010s when ’421 was filed, prepress operations were increasingly managed through automated software workflows at a time when spot color reproduction was typically implemented using fixed process color conversions. When systems commonly relied on standard mathematical translations between color spaces rather than localized physical testing, hardware and software constraints made achieving consistent output across different environmental conditions and ink sources non-trivial. During this era, the digital manipulation of page description language files was standard, but the physical variance of print engines often resulted in a disconnect between the colors viewed on a monitor and the final printed media.
Prosecution Position
The examiner allowed the application because the prior art did not suggest a specific method for improving spot color accuracy that involves printing a physical swatch page for a user to evaluate. Specifically, the examiner noted that the prior art lacked the combination of identifying spot colors in a document, generating a physical test print of color tiles, and then allowing a user to input a numerical value from the preferred tile back into the workflow software to update the document file. Additionally, the examiner found no motivation in existing records to modify a page description file by converting a user-selected numerical value into a corresponding color value in a different color space to ensure visual satisfaction.
Claims
This patent contains 30 claims, with independent claims numbered 1, 17, 23, 27, 29, and 30. The independent claims generally focus on methods and systems for improving spot color reproduction in a printing workflow by using color swatches. The dependent claims generally elaborate on the specifics of the methods and systems described in the independent claims, adding details regarding color tile arrangements, numerical value assignments, and user interface elements.
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US8743421
- Application Number
- US13549502A
- Filing Date
- Jul 15, 2012
- Publication Date
- Jun 3, 2014
- External Links
- Slate, USPTO, Google Patents