ISF Video Standards & Signal Processing 2 — Questions and Answers
Question 1: What is the active line period in a 1080i/60 signal?
- The time during which picture content is transmitted on each line (Correct answer)
- The blanking interval between frames
- The duration of the vertical sync pulse
- The time required to scan the full 1080 lines
Correct answer: The time during which picture content is transmitted on each line
The active line period is the portion of each horizontal line interval during which actual picture (luminance and chrominance) data is transmitted.
Question 2: In HDMI, what does the term 'deep color' refer to?
- Higher color bit depth beyond 8 bits per channel (e.g., 10 or 12 bits) (Correct answer)
- A wider color gamut such as DCI-P3
- Increased color saturation through signal processing
- HDR tone mapping applied at the display
Correct answer: Higher color bit depth beyond 8 bits per channel (e.g., 10 or 12 bits)
Deep color in HDMI refers to color bit depths greater than 8 bits per channel, allowing 10, 12, or 16 bits per channel to reduce banding.
Question 3: Which chroma subsampling scheme retains the most color information?
- 4:4:4 (Correct answer)
- 4:2:2
- 4:2:0
- 4:1:1
Correct answer: 4:4:4
4:4:4 subsampling samples both luma and both chroma channels at full horizontal and vertical resolution, preserving all color detail.
Question 4: What is the purpose of pre-emphasis in video signal transmission?
- To boost high-frequency components before transmission to compensate for cable losses (Correct answer)
- To reduce the overall signal amplitude before encoding
- To apply gamma correction to the video signal
- To synchronize audio with video over long cable runs
Correct answer: To boost high-frequency components before transmission to compensate for cable losses
Pre-emphasis boosts high-frequency signal components before transmission so that after the cable attenuates those frequencies, a flat response is restored.
Question 5: What does the CIE 1931 xy chromaticity diagram represent?
- A 2D map of all colors visible to the human eye, independent of luminance (Correct answer)
- The relationship between gamma and brightness in display devices
- The color gamut of the sRGB color space only
- A plot of signal voltage versus color temperature
Correct answer: A 2D map of all colors visible to the human eye, independent of luminance
The CIE 1931 xy chromaticity diagram plots all perceivable colors as a 2D horseshoe shape, with luminance (Y) factored out.
Question 6: In SDI (Serial Digital Interface), what is the function of cable equalization?
- To compensate for high-frequency attenuation introduced by long cable runs (Correct answer)
- To convert balanced audio embedded in the SDI stream
- To re-clock the signal to remove jitter at the source
- To convert SDI to HDMI format at the receiver
Correct answer: To compensate for high-frequency attenuation introduced by long cable runs
Cable equalization at the SDI receiver boosts attenuated high frequencies so that the signal's frequency response is flat after passing through a long cable.
Question 7: Which standard defines the color primaries and transfer function used by HDR10?
- ITU-R BT.2020 primaries with SMPTE ST 2084 (PQ) transfer function (Correct answer)
- ITU-R BT.709 primaries with sRGB transfer function
- DCI-P3 primaries with gamma 2.6 transfer function
- ITU-R BT.2020 primaries with HLG transfer function
Correct answer: ITU-R BT.2020 primaries with SMPTE ST 2084 (PQ) transfer function
HDR10 uses the wide-gamut BT.2020 color primaries combined with the Perceptual Quantizer (PQ) transfer function defined in SMPTE ST 2084.
ISF Video Standards & Signal Processing 2
What is the active line period in a 1080i/60 signal?