Snell & Wilcox Zone Plate
Snell & Wilcox SW2 and SW4 "Zone Plate" Test Chart were TV test cards introduced in the 1990s and used with NTSC, PAL and SDTV systems.
Popular versions of the test charts were made available on Laserdisc and DVD-Video, allowing home users and professionals to test and calibrate their equipment. Several broadcast widescreen variations exist.
They were created using equipment like the Snell & Wilcox TPG20/21 Test Pattern Generators.
Features
The Snell & Wilcox Test Chart #2 is used for general adjustments of video processors, mixing equipment, and display devices such as CRT TVs and projectors. Main features and tests allowed by the chart are:- Boundary markers
- Interlace check
- Tartan bars
- Circular grayscale
- Chart format
- Registration check
- Vertical frequency response check
- Horizontal and Diagonal frequency response check
- SECAM bell filter check
- Frequency response wedge
- Radial wedge
- Moving zone plate
- Chroma frequency response
- Y/C timing checks
- PLUGE
- Pulse and Bar
- Chroma non-linearity
- Chroma tests