BitsPlusCSFDemo([screenid=max] [, gamma = 2.2][, method=0][, charttype=0])

This demo utilizes the Psychtoolbox imaging pipeline. Therefore it won’t
work on gfx-hardware older than ATI Radeon X1000 or NVidia Geforce 6000.

Demonstrates advantage of the 14 bpc Mono++ display mode, and similar high
bit depths display modes over the standard 8 bpc display mode of standard
graphics hardware. The demo displays either the Campbell-Robson CSF chart
if you set ‘charttype’ == 0, or a linear intensity gradient, if you set
‘charttype’ == 1. By default, the CSF chart is shown.

The optional ‘method’ argument selects among different display output

A ‘method’ of 0 outputs to a regular 8 bit framebuffer. This is the
default, if no method argument is provided.

A ‘method’ of 1 tries to utilize the native 10 bpc framebuffers of recent
AMD/NVidia hardware.

A ‘method’ of 2 uses a method known as “PseudoGray” or “Bitstealing” for

In ‘method’ == 3, the Mono++ display mode of the Bits++ box is used.

A ‘method’ == 4 uses the Xiangrui Li et al. “VideoSwitcher”, video
attenuator device.

In ‘method’ == 5, the M16 display mode of the VPixx - DataPixx box is used.

A ‘method’ of 6 tries to utilize the native ~11 bpc framebuffers of recent
AMD hardware.

A ‘method’ of 7 tries to utilize the native up to 16 bpc framebuffers of recent
AMD hardware.

The optional ‘gamma’ parameter allows to select the initial gamma value
of your display to correct for. This can be changed interactively later

The optional ‘screenid’ parameter allows to select the id of the output
display on multi-display setups. By default, the secondary display is

Keyboard control keys

At each press of space key, the display alternates between a high bpc
version and a 8 bpc version to hopefully show a perceptible difference in
contrast resolution. The ESCape key exits the demo.

The left- and right cursor keys allow you to change the gamma-correction
setting. The demo starts with standard power-function gamma correction
for a display with gamma 2.2, i.e., out = in ^ (1/gamma) with gamma =

This demo is derived from a similar demo (written in C) which is part of
the sample code collection for Bits++ from Cambridge Research Systems
support website. It mostly replicates that C sample, however there are
small differences.

The original description of the CSF chart seems to be in (not checked):
Campbell, F. W. and Robson, J. G. (1968) Application of Fourier analysis
to the visibility of gratings. Journal of Physiology (London) 197:

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