An important part of any production is assuring that what you are seeing is what is going to air, tape or disc. Because one observer may see a particular color differently than another, the best way to assure you are getting proper color and luminance levels is with a Waveform Monitor and Vectorscope. All is not lost if you are in a situation where these devices are not available. Here is an alternative method for quantifying color through the use of standard test patterns from The Society Of Motion Picture And Television Engineers (SMPTE) and the use of optical viewers.
- Assure that the monitor is in its normal viewing environment. Avoid any direct reflections in the monitor screen.
- Turn the monitor on and let it stabilize for about 15 minutes.
- Send a known standard video signal to your monitor, like SMPTE Bars.
- Lower the color level to a black and white image. Observe the black and white bars to ensure they do not look slightly tinted.
- Reset the chroma or color control to bring back the color image. Some monitors have a detent in the control. When set to the factory default a tactile detent will be felt while operating the control.
- While observing SMPTE Bars on the screen, adjust the brightness control for proper black level. Adjust brightness while observing the level of the 3 small black bars at the lower right of the screen. Stop when the lightest bar at the right is barely visible.
- Now set the contrast control (sometimes called picture) for proper white level. One way to find this point is to first turn the contrast all the way up. As this is done the white bar at the lower left on the screen will brighten and flare. At this point, turn the contrast control slowly back down, reducing the bloom until the white square itself just begins to respond.
- If the monitor has a “Blue Screen” switch, switch it on. If your monitor does not have a blue screen switch you can use a Wratten 47B filter to observe the screen. Only the four color bars containing some blue signal (gray, cyan, magenta and blue) and their sub-bars should now be visible.
- Adjust the color saturation with the same chroma or color control used in step 5 until the gray and blue bars (the bars at the far left and far right) are of equal brightness. Then adjust the Hue control (Sometimes called Tint or Phase) until the cyan and magenta bars are of equal brightness. Now these four bars should be of equal intensity, and the other three bars should be entirely black. This is the correct adjustment!
- Now turn off the blue only screen. Bars should now appear normal. Visually recheck black and white levels and that the bars are correct in hue and color. Yellow should appear yellow not reddish or greenish and magenta should be just that — not purple or pink.
That’s all there is to it. -33-