7.3" e-paper image converter

7.3-inch e-paper panels have a resolution of 800×480 pixels. They are available as 6-color, 7-color. Pick the resolution and colors that match your panel, upload a photo and DitherInk will crop it, dither it with its tuned Atkinson algorithm and give you a file your firmware can use directly.

Portrait or landscape?

The panel always receives its buffer in its native 800×480 layout. If your frame stands upright, choose Portrait: you crop a 480×800 image and DitherInk rotates the buffer 90° counterclockwise before writing the file. If your driver expects a different rotation, change it under Advanced output options.

Which file should I download?

• .h: a C array you can #include in an Arduino or ESP-IDF project. Easiest for a single fixed image.
• .bin: the raw frame buffer. Store it on an SD card or in flash and stream it to the panel. Best when images change.
• .png: an indexed PNG whose pixel values are the color codes. Handy for Python on a Raspberry Pi.
• .bmp: an indexed bitmap for photo frames and tools that read BMP files.

Tips for 6-color

Real panel colors are darker and less saturated than screen colors. DitherInk matches against a brightened palette so light areas stay light, and Auto mode boosts muted colors before dithering.

Example code (800×480, 6-color)

Arduino / ESP-IDF with the .h file

#include "my_image.h"  // downloaded from DitherInk

// MY_IMAGE_WIDTH x MY_IMAGE_HEIGHT = 800 x 480, color_4bpp
// Color codes: black=0, white=1, yellow=2, red=3, blue=5, green=6
// The buffer is already in the panel's native orientation.

void showImage() {
  epd_write_frame(my_image, MY_IMAGE_SIZE);  // your driver's full-frame write
  epd_refresh();
}

Replace epd_write_frame and epd_refresh with the functions your display driver provides. Most drivers have a function that takes a full frame buffer.

ESP32 loading the .bin file from flash

#include <LittleFS.h>

constexpr size_t FRAME_BYTES = 192000;
// Large buffer: allocate in PSRAM on ESP32 boards that have it.
uint8_t* frame = (uint8_t*)ps_malloc(FRAME_BYTES);

bool loadFrame(const char* path) {
  File f = LittleFS.open(path, "r");
  if (!f || f.size() != FRAME_BYTES) return false;  // wrong size = wrong panel settings
  f.read(frame, FRAME_BYTES);
  f.close();
  return true;
}

Python (Raspberry Pi) reading the .bin file

import numpy as np

data = np.fromfile("my_image.bin", dtype=np.uint8)
assert data.size == 192000
codes = np.stack([data >> 4, data & 0x0F], axis=-1).reshape(480, -1)[:, :800]

Not sure about your panel's details? See how e-paper frame buffers are laid out.