Profiling Target Sheet Patch Count: A Comprehensive Analysis

Overview

Profiling a printer for accurate color reproduction is a critical aspect of digital printing. The discussion revolves around the impact of varying the number of colors on profiling targets and its influence on creating high-quality ICM color profiles. The i1Profiler package by x-Rite, utilizing an i1Pro2 spectrometer and i1io2 scanning table, is the tool of choice in this exploration.

Test Setup

Step 1: Varying Color Counts

The initial step involves testing an Epson ET-8550 printer with Epson 106 inks, Aldi Netbit paper sheets, and color targets ranging from 96 to 2880 patches. The i1Profiler software facilitates the creation of targets with a flexible color count. To achieve a target with 96 patches, the Colorport software becomes instrumental. The resulting profiles were analyzed based on the overlap of profile volumes at different luminance levels.

Analysis Results

Profiling Accuracy

The profiles exhibited close alignment in shape and volume across various patch counts, except for a deviation in the 283-patch profile. Dark-end luminance at L=15 demonstrated consistency, emphasizing that shape and volume alone do not fully represent profiling performance.

Step 2: Comparative Analysis

A subsequent test involved printing a 96-color target with profiles generated from both 96 and 2880 color targets. The i1Profiler software's data analysis function allowed a detailed comparison. Deltas exceeding acceptable magnitudes were evident, prompting the exclusion of the problematic target sheet setup.

Comparative Performance

Interestingly, the comparison between profiles based on 96 and 2880 colors revealed nearly identical performance for the 96-color test sheet. The profile based on 400 color patches also performed exceptionally well, indicating minimal differences in accuracy between 96 and 2880 color patches.

Further Exploration

Extended Color Patch Testing

To delve deeper, a new test was initiated by printing a 400-color patch sheet. This sheet was printed with profiles based on both 96 and 2880 color patches. The goal was to assess if higher patch counts translate to improved print quality.

Color Space Analysis

A ColorInspector Java applet visualized the distribution of 400 color patches across the RGB color space. The corresponding printer profile demonstrated instances where it exceeded the sRGB and even the wider Adobe color space. This raised questions about the assumed correlation between higher patch counts and profile accuracy.

Statistical Data Analysis

Using the i1Profiler software, scans of prints with 400 patches were compared, displaying various statistical data. Surprisingly, profiles created from 96 patches exhibited a low average DeltaE of 1.59 when compared to profiles from 2880 patches. This challenges the assumption that higher patch counts inherently result in more accurate profiles.

Conclusion

This comprehensive analysis challenges conventional beliefs regarding the correlation between patch count and profiling accuracy. The results suggest that, at least in this test scenario, profiles created from 96 patches perform as well as those created from 2880 patches. The intricacies of color reproduction and profiling may vary, and further exploration with different profiling tools and parameters is warranted.

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