Display Validation Toolbox (DVT)

A MATLAB/Psychtoolbox toolbox for validating the temporal, luminance, contrast, and spatial accuracy of display systems used in psychophysics experiments.

Vision science experiments routinely assume that a monitor presents stimuli at the requested time, luminance, contrast, and spatial frequency. This toolbox provides a standardized, repeatable set of tests to verify those assumptions on a given display setup rather than taking them for granted, and produces a self-contained report documenting the results.

The toolbox is designed to be display-agnostic. It tries to not assume any particular monitor, GPU, or operating system, in favor for all display-specific parameters being set through a single configuration file.

Tests

The toolbox runs four independent validation modules:

Module	Name	Description
A	Temporal Accuracy	Measures inter-frame intervals (IFI) under idle, loaded, and long-duration presentation conditions to detect dropped or delayed frames relative to the expected refresh rate.
B	Luminance & Gamma	Measures luminance across a range of pixel values with an external photometer, fits the display's gamma function, and generates a gamma correction lookup table.
C	Contrast Precision	Measures the smallest stimulus contrast the display can reproduce reliably, useful for defining the floor of contrast-sensitivity experiments.
D	Spatial Accuracy	Verifies output resolution, pixel-level scaling, and the accuracy of rendered spatial frequencies (cycles per degree) against the display's Nyquist limit.

Each module produces figures, CSV data tables, and printed diagnostics. Results from all modules are compiled into a single HTML report (report.html) with pass/fail criteria for each test.

Requirements

• MATLAB (developed/tested on a recent release)
• Psychtoolbox-3
• A photometer or colorimeter (required for the Luminance & Gamma test, Module B)
• A display supporting 10-bit output is recommended for the gamma and contrast tests, but not required. Native 10-bit framebuffer output also requires GPU/driver/OS support (e.g. a Quadro/Studio-class NVIDIA card with the appropriate driver configuration on Windows, or a depth-30 Xorg configuration on Linux). If MONITOR_BIT_PRECISION in DVT_config.m is set to 8 or below, the toolbox will not request native 10-bit output, which avoids window-creation errors on setups that don't support it.

Usage

1. Open DVT_config.m and set the parameters for your display and viewing setup (see Configuration below).
2. Run DVT_run.m from the project root.
3. For Module B (Luminance & Gamma), follow the on-screen prompts to take photometer readings at each requested pixel level.
4. Results are saved to a timestamped folder under results/, containing:
   • report.html — a formatted summary report with figures and pass/fail status
   • result.mat — all raw results as a MATLAB struct
   • Per-module figures (.png) and data tables (.csv)
   • A generated gamma correction table (.mat), if Module B was run

Configuration

All configurable parameters live in DVT_config.m:

Parameter	Description
TEMPORAL_TRIALS_TIMING	Number of trials for the basic and load timing tests (A1, A2)
TEMPORAL_TRIALS_LONG_TIMING	Number of trials for the long-run stability test (A3)
TEMPORAL_BIN_WIDTH	Histogram bin width (ms) for timing results
MONITOR_BIT_PRECISION	Bit depth of the display, used to size the gamma correction table
MONITOR_PIXEL_WIDTH / MONITOR_PIXEL_HEIGHT	Expected display resolution
GAMMA_TABLE_NAME	Filename for the saved gamma correction table
SPATIAL_ROW_INDEX / SPATIAL_ROW_WIDTH_CHECK	Row and range used to inspect the checkerboard pattern in the spatial test
VIEWING_DISTANCE_M	Viewer-to-screen distance (m), used to convert cycles/pixel to cycles/degree
SCREEN_WIDTH_M	Physical screen width (m)

Project Structure

DVT_run.m           Main entry point - initializes PTB and runs all test modules
DVT_config.m        User-editable configuration
tests/              Individual test modules (temporal, gamma, contrast, spatial)
utils/              Report generation
results/            Timestamped output folders (generated at runtime)

Citation

This toolbox was developed as part of a summer research program in collaboration with KTH Royal Institute of Technology. If you use it in published work, please contact the authors for appropriate citation details.