Have you ever seen color bars and wondered about their purpose in life? Perhaps you were skipping through TV channels late at night when you came across a station that was airing color bars. Well, those patterns serve a far greater purpose than that of a visual place holder. They are what television, motion media, production, and film professionals rely on as a tool to properly calibrate their displays/viewfinders and if you’re lucky enough to have a monitor that has a mode called “blue only” or similar than you can adjust yours in the following manner, just like a pro.
1) Turn on your TV
2) Feed color bars to the display panel (you may have to get creative with your input device if you aren’t using professional equipment/software with that capability)
3) Set your contrast/picture control to its midpoint
– Adjusting Brightness –
4) Take your color/chroma control setting and position it all the way to the left or down until the video on the screen becomes black and white
5) Notice there are roughly 6 evenly spaced boxes at the bottom of the screen; look closely at the second box from the right (that one consists of 3 skinny strips of various gray/black levels)
6) Adjust your monitor’s brightness setting until the middle strip is not quite visible; you’ll find that the strip next to it on the right is barely visible if you’ve properly set your display’s brightness & there should now be no difference between the other two strips, forming a larger black box (tweak your settings more if you are still noticing a dividing line between the two left most strips)
7) Use your monitor’s contrast setting to set your white level by turning it all the way up. You’ll notice that the 2nd box from the left along the bottom becomes very bright and the middle strip from step number 6 is once again visible; back the contrast setting off or down. Once the contrast setting is properly calibrated you’ll notice that only the strip on the right from the box of 3 that you previously adjusted in step 6 is visible
– Adjusting Color –
8) Engage your monitor’s blue only mode
9) Now adjust the color/chroma setting so that the gray bar at the (tall outside left) and the blue bar (tall outside right) at the right are equally as bright
10) Adjust the hue until the cyan and magenta bars are equally as bright (the inner two that now look blue)
11) Your monitor is now calibrated
Professionals use scopes to measure this information within their picture. The four main types consist of vectorscope (measures color information), waveform (measures the level of a particular video signal), the histogram (which measures overall exposure of an image), and the RGB Parade (a helpful view similar to the waveform but separated based upon color channels red, green, and blue that comprise of a video picture).
The photo above represents the appearance color bars have whereas the image below is typical of what one might find when analyzing a video clip.
This information is helpful to colorists, who use it as a reference when making corrections and enhancements. On a vectorscope, you can see how if the scope is fed color bars, each color lands directly in its correct box accordingly. The waveform monitor helps to show an image’s dynamic range. The blacks are at the bottom while the whites are at the top and the histogram is similar in that the blacks are on the left and whites on the right (though a histogram is a visual representation of the overall image luminance values from 0-255 where 0 is black and 255 is white). The waveform differs in the sense that it shows a visual representation of the brightness for each vertical line that the picture is comprised of (so it may be possible to see a likeness of the image to a degree)