What is a Pixel Bar Chart?
The basic idea of a pixel bar chart is to present the data values directly instead of aggregating them into a few data values. The approach is to represent each data item (e.g. a customer) by a single pixel in the bar chart. The detailed information of one attribute of each data item is encoded into the pixel color and can be accessed and displayed as needed.
Source: Pixel bar charts: a visualization technique for very large multi-attributes data setsUsage
Our idea is to use one or two attributes to separate the data into bars (dividing attributes) and then use two additional attributes to impose an ordering within the bars (see Figure 3 for the general idea). The pixel bar chart can therefore be seen as a combination of the traditional bar charts and the x-y diagrams. The result is a visualization in which one pixel corresponds to one customer
Source: Pixel bar charts: a visualization technique for very large multi-attributes data sets
Source: From Bar Charts to Pixel Bar Charts
