Playback Filter Descriptions

The QCTools preview window is intended as an analytical playback environent that allows the user to review video through multiple filters simultaneously. The playback window includes two viewing windows which may be set to different combinations of filters. This allows a user to playback a video by viewing a waveform and a vectorscope or perhaps view a waveform and the video with highlighted pixels that are outside of broadcast range.

Normal

This view simply shows the video as QCTools interprets it, no special effects or filtering are added.

Field split

All odd numbered lines of video are presented in the top half of the frame and the even numbered lines of video are presented on the bottom half. Often video decks read odd and even lines of video using different video heads. When the video deck is dirty or poorly maintained the two video heads may play back very inconsistently. This filter highlights the difference in the video field 1 and video field 2 by showing them separately.

Field diff

This presentation visualizes the difference between video field 1 and field 2. A middle gray image would mean that field 1 and field 2 were identical, whereas deviation to white or black indicates a difference.

Histogram

The histogram shows the frequency of occurrence of values per channel. Typically the histogram will show one graph per channel (one for each Y, U, and V or one for each red, green, and blue).

Histogram - Field Split

Same as the histogram except field 1 is shown on the left and field 2 on the right.

Waveform

The waveform plots the brightness of the image, each column of the waveform corresponds to a column of pixels in the source video. The pixels of each column are then plotted in a scale from 0 to 110 IRE. The range from 0 to 7.5 IRE is highlighted in blue and indicates a black value that is below traditional NTSC broadcast range. The range from 100 to 110 IRE is highlighted in red and indicates a white value that is above broadcast range. For most analog media the intended pixel luminsotiy values should exist between 7.5 and 100 IRE.

Waveform - Field 1

Same as Waveform but only depicts field 1.

Waveform - Field 2

Same as Waveform but only depicts field 2.

Waveform - Field 1

Same as Waveform but only depicts field 1.

Waveform - Field Split

Same as Waveform but depicts field 1 and field 2 separately (field 1 on top and field 2 on bottom).

Broadcast Range Pixels

This is the same presentation as 'Normal' except that pixels that are outside of broadcast range are highlighted as white.

Broadcast Range - Field Split

Same as 'Broadcast Range Pixels' except that field 1 is depicted on the top and field 2 on the bottom.

Vectorscope

A vectorscope display. This display plots chroma values (U/V color placement) in two dimensional graph (which is called a vectorscope). It can be used to read of the hue and saturation of the current frame. The whiter a pixel in the vectorscope, the more pixels of the input frame correspond to that pixel (that is the more pixels have this chroma value). The V component is displayed on the vertical (Y) axis, with the bottom edge being V = 0 and the top being V = 255. The U component is displayed on the horizontal (Y) axis, with the left representing U = 0 and the right representing U = 255.
Six blocks are highlight to depict standardized color points for red (90, 16), green (54, 222), blue (240, 146), cyan (166, 240), magenta (202, 44), and yellow (16, 110). All valid chroma values fall within a circlular shape from the center to the outer edge of the plot.

Vectorscope - Field 1

Same as Vectorscope but only depicts field 1.

Vectorscope - Field 2

Same as Vectorscope but only depicts field 2.

Vectorscope - Field Split

Same as Vectorscope but depicts field 1 and field 2 separately (field 1 on left and field 2 on right).

Temporal Outlier Pixels

This is the same presentation as 'Normal' except that pixels that are labelled as temporal outliers are highlighted as white. Temporal outliers are pixels that significantly differ from their neighbors and often correspond to tape damage or playback error.

Temporal Outlier - Field Split

Same as 'Temporal Outlier Pixels' except that field 1 is depicted on the top and field 2 on the bottom.

Extract Y

Presents only the Y channel in grayscale or luminosity of the video.

Extract U

Presents only the U channel in grayscale or part of the chromiance of the video.

Extract V

Presents only the V channel in grayscale or part of the chromiance of the video.

Extract Y - Equalized

This filter extracts the Y channel which represents the luminosity data from the video and then applies a histogram equalization which redistributes the pixel intensities to equalize their distribution across the intensity range. This filter is useful for analyzing compressed video channel signals.

Extract U - Equalized

This filter extracts the U channel which represents part of the chroma data from the video and then applies a histogram equalization which redistributes the pixel intensities to equalize their distribution across the intensity range. This filter is useful for analyzing compressed video channel signals.

Extract V - Equalized

This filter extracts the V channel which represents part of the chroma data from the video and then applies a histogram equalization which redistributes the pixel intensities to equalize their distribution across the intensity range. This filter is useful for analyzing compressed video channel signals.