Vertex HGSG
Grey Scale Chart (11 Step Gamma Compensated)

• 16:9 & 4:3
• Chart size 10" x 16.5"

Vertex HGSG Shown

The 11-Step Grey Scale Chart is an extended range test chart intended for use with high-performance video cameras including both CCD and tube types.  The chart consists of two arrays of 11 neutral grey patches or "chips" ranging in reflectance from 2% to approximately 90% (about 5.5 f-stops).  The arrays are arranged so that one increases in reflectance from right to left and the other increases from left to right.  The strips are mounted on a uniform grey background with a reflectance of 16%.  A black-white-black test object in the center of the chart provides a black (< 0.5% reflectance) reference for adjusting dead black level in amplifier set-up as well as a "super-white" (~90% reflectance) patch for setting peak video in many applications.  The black regions can also be used for flare compensation adjustment.

The grey scale values are chosen according to a power law producing a "Gamma" value of 2.2, the characteristics value for television receivers and monitors.  To provide an overall system gamma of unity, the video camera is usually adjusted to a Gamma of 1/2.2 = 0.45.  With the Gamma Compensated Chart, the video signal from a camera adjusted to that value will appear as a linear "staircase" (equal steps) when viewed on a waveform monitor.

Ordering Information

Model

Description

Buy Online

Price