E-Ink explains their ACeP technology as such:
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https://www.eink.com/color-technology.html
"
Advanced Color ePaper (ACeP™) is a high quality, full color reflective display. In the ACeP™ system, the ink can produce full color at every pixel, without the use of a color filter array (CFA).
ACeP™ achieves a full color gamut, including all eight primary colors, using only colored pigments. The display utilizes a single layer of electrophoretic fluid which is controlled using voltages compatible with commercial TFT backplanes. The fluid can be incorporated into either microcapsule or Microcup® structures. The richness of the colors is achieved by having all the colored pigments in every picture element (pixel) rather than the side-by-side pixel colors achieved with a CFA. This eliminates the light attenuation, which can be quite significant. ACeP™ maintains the ultra-low-power and paper-like readability under all lighting conditions of regular E Ink ePaper."
The attached image is from an editorial about all the different color display technologies from E-Ink. It illustrates how the ACeP screen displays colors.
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https://spectrum.ieee.org/how-e-ink-...l-color-epaper