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 | Align levels of sources using test patterns. If you capture some color bars from your source footage, you can measure them and set the color correction needed to restore the video levels to the way the program was created. Import the Test Patterns from the SupportingFiles folder of your Avid system to become familiar with the proper Waveform, Parade, and Vectorscope readings. Histograms are not as useful on test patterns. For example, with 75% color bars, the Y+C envelope for the yellow and cyan bars should match the 100% white level. |
| Identify problems with source video. Typical problems include: |
| – | Color levels too high or too low. See Safe Color Limits with Waveform and Vectorscope Information. |
| – | Missing channels in YCbCr or RGB, indicating an equipment problem or a damaged cable. |
| – | Clipping in YCbCr, RGB, or YC channels. The trace appears chopped at a certain level. If this appears at a level below the maximum, it occurred before the footage was captured. |
| – | Images imported at the wrong level settings. If you import images at RGB levels of 0–255 that you should have imported at 601álevels of 16–235, the images will lack contrast. If the images have too much contrast, with levels exceeding the 0% and 100% markings, the opposite is likely. |
| Match scene brightness across a cut in Y Waveform. |
| Put your flesh tones along a certain hue axis in the vectorscope. |
| Watch the spread of the Y histogram to identify a good contrast range without clipping. |
| Watch the top of the YC Waveform to make sure you do not have too much bright chroma. |
| Fix white balance and black balance problems by identifying and centering those vectorscope traces. |
 | These instruments are showing you the values of only one frame or field at a time. Move around in the clip to find the most extreme levels or those most representative of the scene. |