What is gray color?
 

Gray color refers to pure white, pure black, and a series of transition colors from black to white. The black-and-white photos and black-and-white TVs we usually talk about should actually be called gray-scale photos and gray-scale TVs. Gray-scale colors do not contain any hue, that is, there are no colors such as red and yellow.
 

The highest gray level is equivalent to the highest black, which is pure black. The lowest gray level is equivalent to the lowest black, that is, "no black", that is, pure white. The higher the gray level, the richer the display effect. The SPI black-and-white e-paper on the market currently only supports 2 gray levels, which means that from full black to full white, only two bright and dark screens can be distinguished.
 

In order to meet the customer's pursuit of richer display effects, after unremitting efforts and research, now Good Display's SPI B/W e-paper series can support 4 grayscale displays! This is not only a small step for Good Display to become a better display supplier, but also a big step for the entire e-paper industry to a better display effect!
 

Specific display effect, please see the comparison picture below (example):

So how can we get a display effect of 4 gray levels?
 

The method is very simple. First of all, please select the e-paper with 4 gray levels display function (the catalog of e-paper that can support 4 gray levels is at the bottom of this chapter for reference),then prepare a picture with 16 gray levels and the corresponding demo program which supports 4 gray levels. When the e-paper takes the Bitmap Convert, select 16 gray levels, and then you can get the 4 gray levels display effect.