Print Data Generator Reducing Colorants via HSV Hue Difference
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Solution Overview
Problem
Existing image processing apparatuses that reduce full-color data to two colors for printing often result in a sense of incongruity due to exaggerated red coloration and clear boundaries between red and black pixels, leading to an unnatural appearance in printed images.
Innovation Solution
A print data generator that converts RGB data to HSV data, calculates a difference value between the hue of each pixel and a specified emphasis color, and sets density values based on the saturation and luminance values to create a smoother transition between colors, reducing the number of colors while maintaining color emphasis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If density data for red drawing is calculated with larger coefficient for R density value, then red color is emphasized in printed image, but density gradient becomes higher causing unnatural appearance and sense of incongruity
Solution Approach 1:
The patent changes the color space parameter system from RGB to HSV, and modifies how density values are calculated by incorporating saturation (S) and value (V) components along with hue difference (ΔH). This parameter transformation allows color emphasis through saturation while controlling density gradients through the combined formula: density of emphasis color = S × (1 - ΔH), density of reference color = V. This resolves the contradiction by decoupling color emphasis from excessive density variation.
Solution Approach 2:
The patent introduces dynamic adjustment of density values based on the hue difference (ΔH) between each pixel and the emphasis color. The density calculations are not fixed but dynamically adapt to the local color characteristics: pixels closer to the emphasis hue get higher emphasis color density, while pixels farther away get lower emphasis color density. This dynamic approach creates smooth transitions and natural appearance while maintaining color emphasis where needed.
2Measurement precision
If each pixel is determined to be drawn in red or black separately, then clear boundary is formed between red and black pixels, but unnatural appearance and sense of incongruity occur
Solution Approach 1:
The patent transforms the discrete binary determination (red or black) into a continuous density assignment problem by working in HSV color space. Instead of making hard decisions about which color to assign, the system calculates continuous density values for both emphasis color and reference color based on saturation, value, and hue difference. This continuous parameter approach naturally creates smooth boundaries while maintaining precise color determination through the hue comparison.
3Quantity of substance
If full-color data is reduced to two colors for printing, then colorant usage is reduced, but sense of incongruity and unnatural appearance increase
Solution Approach 1:
The patent uses HSV color space parameters (Hue, Saturation, Value) to maintain color naturalness while reducing to two colors. The hue parameter identifies which color to emphasize, saturation controls the intensity of the emphasis color, and value controls the brightness of the reference color. By calculating densities as S × (1 - ΔH) for emphasis color and V for reference color, the system preserves perceptual color relationships even with limited colorants.
Solution Approach 2:
The patent introduces the hue difference (ΔH) as an intermediary parameter that mediates between the full-color input and the two-color output. This intermediary allows smooth transition and blending effects by modulating the density of emphasis color based on how close each pixel's hue is to the target emphasis hue. This creates natural-looking gradients and transitions that would be impossible with direct binary color assignment.
Data Source
AI summary
A print data generator includes a storage storing processor-executable instructions causing a processor to perform a process to generate print data from original full-color data. The process includes when a hue value of a pixel is within a specific hue range for an emphasis color, setting a density value of a reference color of the pixel based on a value value of the pixel, and setting a density of the emphasis color of the pixel based on a saturation value of the pixel and a difference value between the hue value of the pixel and a hue value of the emphasis color, and when the hue value of the pixel is out of the specific hue range, setting the density value of the reference color based on a luminance value of the pixel derived from RGB data, and setting the density value of the emphasis color to zero.