E-paper color modes: black and white to 7 colors
Choosing an e-paper panel is mostly choosing a palette. The palette decides what images look good, how big the frame buffer is and how long a refresh takes. Here is how the common types compare.
At a glance
| Mode | Colors | Bits per pixel | 800×480 buffer | Typical refresh |
|---|---|---|---|---|
| Black and white | 2 | 1 | 48,000 bytes | 1 to 3 s, partial updates possible |
| 4-level grayscale | 4 | 2 | 96,000 bytes | A few seconds |
| 3-color red / yellow | 3 | 1 + 1 (two planes) | 96,000 bytes | 10 to 20 s |
| 4-color | 4 | 2 | 96,000 bytes | 10 to 20 s |
| 6-color | 6 | 4 | 192,000 bytes | 15 to 30 s |
| 7-color | 7 | 4 | 192,000 bytes | 15 to 30 s |
Refresh times vary by panel, temperature and driver. Treat them as rough ranges.
Black and white
The simplest and fastest panels. Many support partial refresh, so a clock or a counter can update in under a second without the full-screen flash. Text, icons and line art look sharp. Photos work with dithering but look like newspaper prints.
4-level grayscale
The same hardware as many black and white panels, driven with a different waveform to produce two extra gray levels. Dithering patterns become much finer and photos look noticeably smoother. Check that your driver supports the 4-gray mode; it is often a separate initialization routine.
3-color: black, white and red or yellow
These panels add one accent color. They are great for labels, price tags and dashboards where a single color highlights what matters. For photos the accent color is used sparingly, so most images still look mostly black and white with warm touches. Drivers usually expect two buffers: a black and white plane and a color plane.
4-color: black, white, yellow and red
Having both warm colors lets the dithering mix oranges and skin tones. Each pixel is a 2-bit color code, four pixels per byte, in a single buffer.
6-color
Black, white, yellow, red, blue and green cover enough of the color wheel to reproduce most photos convincingly, which makes these panels popular for digital photo frames. Their inks are darker and less saturated than screen colors, so good preprocessing matters: see getting good photos on 6-color e-paper.
7-color
Adds orange to the six above. Orange helps with sunsets, wood and skin. Each pixel is a 4-bit code, two pixels per byte, just like 6-color panels, but the code table is different. Always check your driver’s color codes; DitherInk lets you change them under Advanced output options.
How to choose
- Text, dashboards, weather stations: black and white for fast updates, or 3-color if one highlight color helps.
- Photos that change daily: 6-color or 7-color.
- Photos on a budget or a small panel: 4-level grayscale gives smooth results with fast refresh.
- Battery-powered devices: all e-paper keeps its image without power, but color panels draw current for longer during each refresh.