Print Processor Black Density Adjustment for Text Readability
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Solution Overview
Problem
Existing printers struggle to produce readable printed matter for texts and graphic images with pale colors, as they use insufficient black toner amounts based on RGB values, making these elements difficult to recognize in monochrome printing.
Innovation Solution
A printing apparatus that generates black image data with increased black density for text objects compared to image objects, and performs monochrome printing using black toner, even when cyan, magenta, and yellow toners are not available, by processing RGB values and object types to enhance readability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monochrome printing is performed using K toner based on RGB values from print data, then the printer can produce monochrome output, but texts and graphic images in pale colors become difficult to recognize due to insufficient black toner density
Solution Approach 1:
The patent applies local quality by differentiating black density requirements based on object type. Text objects are assigned a first black density value while graphic objects receive a second black density value, allowing each to be optimized for its specific function. This resolves the contradiction by applying appropriate density locally rather than using a uniform density for all objects.
Solution Approach 2:
The patent changes the parameter of black density based on object classification. By identifying whether an object is text or graphic and assigning different black density values accordingly, the system optimizes readability for text while maintaining visual presence for graphics, resolving the contradiction between readability and visual impact.
2Ease of manufacture
If the printer uses standard RGB to K conversion equations, then the conversion process is simple, but pale colored texts and graphics produce insufficient black toner amounts
Solution Approach 1:
Instead of applying a uniform conversion approach, the patent applies different black density values to different object types locally. Text objects receive higher black density for readability, while graphic objects receive lower density to preserve visual appearance, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent segments the conversion process by object type classification. By separating text objects from graphic objects and applying different conversion parameters to each segment, the system achieves both simplicity through automated classification and precision through type-specific optimization.
3Adaptability or versatility
If the printer operates as a monochrome printer when C, M, and Y toner cartridges are not mounted, then it can continue to print, but color information in print data is discarded
Solution Approach 1:
The patent changes the approach by not discarding color information but rather transforming it. Instead of losing RGB data, the system uses the color values to identify object types and then applies appropriate black density parameters, converting color information into optimized monochrome output without actual information loss.
Solution Approach 2:
The patent converts the apparent harm of operating without color toner into a benefit. By using the available RGB data to inform black density decisions rather than discarding it, the system transforms the limitation into an opportunity for optimized monochrome printing that preserves important visual information.
Data Source
AI summary
A printing apparatus is adapted to receive print data specifying a color of an object to be printed with RGB values and specifying a type of the object as one of a text object, a graphic object and an image object. A print processor is operable to generate black image data from a set of the print data for one page, such that a black density value for one color of at least the text object is made greater than a black density value for the one color of the image object. A print engine is operable to perform monochrome printing with black toner in accordance with the black image data.