This first group of patterns is used to help calibrate each of the red, blue and green colors.
Each image is made up of a sequence of vertical bars in the repeating sequence:
The solid color is either solid black in the left half of the image or full-on color (red, green or blue) in the right half of the image.
The left and right bands are divided up into ten-pixel-high blocks. Each block is a solid color that is one 1/256 brighter than the previous block. These blocks are separated by a contrasting line to make it easier to distinguish them. Note that the left and right bands are both the same color despite some minor optical illusions due to the contrasting lines.
The striped part is made up of one pixel-high bands alternating between solid black and full-on color. When viewed from a distance or when squinting, this provides a reference point against which we will attempt to calibrate the 50% intensity colors.
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Most LCD screens can only represent 18-bit color (6 bits each of red, green and blue) and use tricks to emulate 24-bit color. These test images make it easy to spot these tricks.
Each of these two images consists of nested blocks of solid color that are one intensity level apart. This may be easier to see in this example where borders have been placed around each block.
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