The Winnov Vectorscope is both a waveform monitor, to visualize the video amplitudes, as well as a vectorscope, to visualize the color amplitude and color phase. This applet is included free of charge with a Videum capture card and the WDM driver.

Waveform monitor
The waveform monitor displays a graph of the video signal. On the horizontal axis it shows one scanline. On the vertical axis it shows the amplitude of the luminance (Y) signal and the chrominance signals (U and V). The values for Y range from 0 to 255. The values for U and V range from -127 to +127. The horizontal axis shows one scan line. The scan line may be selected by the vertical slider.

The first screenshot shows a test image captured from a DVD player through the composite video input of a Videum 4400 AV card. In the middle there are 8 grayscale bars. They can be nicely identified as the staircase waveform on the left. If contrast and brightness are set up correctly the leftmost step (black bar) should be at 0 (minimum value) and the rightmost step (white bar) should be at 255 (maximum value).

The second screenshot shows a test image with 8 color bars. Here the wareform monitor has been set up to show all three waveforms for luminance (Y) and the 2 chrominance signals (U and V). Note that the brightness and contrast settings are not perfect. The leftmost step of the luminance waveform (purple graph) does not reach the top. And the rightmost step of the luminance waveform does not reach the bottom. So the white and black are not saturated.

Vectorscope
While a waveform monitor displays amplitude information about all parts of the signal, a vectorscope displays information about only the chrominance (coloring) portion of the video signal. It does not respond to other parts of the video signal. There are two parameters of the chrominance signals (U and V) that may suffer distortions leading to noticeable picture problems. These are amplitude (gain), and phase (timing).

Amplitude may also be measured with the waveform monitor. But the vectorscope is needed to measure the timing relationship between U and V. With the vectorscope you can detect and evaluate both phase and gain distortions of the chrominance portion of the video signal.

Click one of the screenshots, to enlarge it to full size. Please note, that the screenshots above do not show a SMPTE color bars test signal. Please use such color bars to calibrate your video settings.