Datavideo TLM-170FM, Instruction Manual

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Histogram
The histogram is a great tool that helps you to improve the overall exposure of the image.
Y (Luminosity)
The Y or luminosity histogram is a graph that describes the human-eye perceived brightness
distribution within an image.
To produce the luminosity histogram, first break an image into individual pixels, then each pixel is
converted so that it becomes a luminosity based on a weighted average of the three colors at that
pixel. The green, red, and blue channels account for 59%, 30% and 11% of the perceived luminosity
respectively. This is because human eye is more sensitive to green light than it is to blue or red light.
Finally the luminosity histogram is produced by counting how many pixels are at each brightness
level as shown in the diagram below.
RGB
The RGB histogram is a graph that represents the overall brightness of the entire image.
In any digital image, each individual color is made by combining red, green and blue lights with
each light represented by its brightness level ranging from 0 to 255. Therefore every color
produced in this way has a specific brightness value based on mixes of red, green and blue
throughout the image and these brightness values of all the different colors in an image are
represented in a histogram which is known as the RGB histogram.
On the TLM-170F, the RGB histogram is shown with the color overlay as depicted in the diagram
below.