Application-specific software module for evaluating the quality of head-up display system projections
Head-up displays (HUDs) pose unique measurement challenges for manufacturers, who must account for projected image luminance, contrast, and clarity regardless of ambient conditions, virtual image positions, or focal distances on an infinite viewing plane. Comprehensive HUD testing requires both photometric (light data) and dimensional (spatial data) measurement combined to ensure the accuracy of information conveyed to a vehicle operator within a rapidly changing, real-world environment.
Part of the Radiant Vision Systems TrueTest™ Software family, the TT-HUD module provides all of the benefits of TrueTest Software to efficiently perform light, color, and dimensional measurements with specific tests used to evaluate the quality of augmented projections, such as those emitted by head-up display (HUD) systems. A comprehensive HUD test solution from Radiant combines the TT-HUD application-specific software module, and a ProMetric® Imaging Colorimeter or Photometer with 200 mm electronically-controlled lens to perform rapid, automated visual inspection of head-up displays.
TT-HUD uses a ProMetric imaging system to test all HUD characteristics simultaneously, capturing and processing data much faster and more consistently than a spot measurement device or machine vision system alone or combined. In a single hardware/software system, TT-HUD can be used to evaluate all visual aspects of the HUD system as well as test to the specific parameters documented in automotive standards:
- SAE J1757-1 “Standard Metrology for Vehicular Displays”
- SAE J1757-2 “Optical System HUD for Automotive”
- ProMetric Imaging Photometer or Colorimeter (16, 29, or 43MP options)
- Windows® 10, 64 bit
- 16-32 GB RAM
- Additional system requirements vary by camera.
Complete optical measurement solution for head-up displays includes a single camera (imaging colorimeter or photometer, to 43-megapixel resolution) and TT-HUD software test suite.
Comprehensive HUD Test Suite
Tests for HUD quality include photometric measurements used to evaluate properties of light (brightness, contrast) as well as spatial measurements used to evaluate projection quality (distortion, warping) against defined tolerances. TT-HUD allows users to define a complete set of measurement parameters and pass/fail criteria for all points of interest within HUD test images. The software module includes standard display tests, as well as specific tests and test images for optical HUD evaluation including:
TT-HUD applies tests specific to HUD measurement, including Distortion Grid and Checkerboard Contrast. Modulation Transfer Function (MTF) line pair algorithms calculate contrast at different spatial frequencies to determine image clarity.
TT-HUD detects duplicate projections (overlapping or separated from the primary image) that are caused by ghosting effects using a Ghosting Analysis function.
Based on the TrueTest Software test sequencing platform, tests from the TT-HUD test library can be added to a sequence. These sequences are stored, so multiple sequences can be created and recalled as needed. In addition, test parameters and pass/fail settings may be set for each test to create qualification criteria unique to each manufacturer’s requirements. The entire sequence can be run end-to-end automatically. Individual test results are displayed and can be recorded in a report.
Image Distance and Location
Using TT-HUD in Focus Mode, users can easily calculate the real distance of images in the projection at various focal distances on the infinite plane.
Leveraging the electronically-controlled lenses of Radiant ProMetric imaging systems, TT-HUD software converts camera focal distance to real distance units to measure the exact image location as projected out to several meters. This is especially critical for determining image sharpness and clarity at various focal depths, such as for AR-HUD systems where images may be projected at a range of distances.
Using Focus Mode in the TT-HUD software interface, camera lens focus can be electronically controlled. When best focus is achieved, focus distance shows the distance in meters of the projected image.
Because TT-HUD provides the same functional capability of Radiant’s TrueTest Software platform, a Radiant HUD measurement system includes TrueTest software API to customize interfacing and communication with the HUD system. API can be used to control test images projected by the HUD system, trigger the connected imaging system (ProMetric Imaging Photometer or Colorimeter) to capture a measurement image, and synchronize the defined TT-HUD test in sequence for fully-automated testing. This complete system integration offers unrivaled efficiency for testing optical quality parameters of the HUD projection system in a matter of minutes.
Illustration of a HUD measurement system, where software API is used to control and test multiple test patterns in sequence.
Multiple System Configurations
TT-HUD can be used with any ProMetric Imaging Colorimeter or Photometer, providing multiple options to achieve the field of view, pixel resolution, dynamic range, color measurement, and cost requirements for your application.
Supported by Radiant's global support staff and distribution network, TT-HUD is field-proven and has been used to test the optical quality of HUD systems for leading brands worldwide.
TT-HUD Module Key Features and Highlights:
- Quickly apply pre-defined tests for advanced HUD measurement.
- Software test sequencing and API device integration to control display test images in conjunction with software analyses, enabling automated production-level testing.
- Apply tolerances and obtain pass/fail data to enable in-line quality control.
- Supports Society of Automotive Engineers standard requirements for HUD optical measurement (SAE J1757-1) and methodology (SAE J1757-2).
- Single test suite captures luminance, chromaticity, and dimensional measurement data for analysis.
- Data analysis functions, including bitmaps, isoplots, and cross-sections.
TT-HUD enables evaluation of the optical quality of virtual images projected by head-up displays, with absolute luminance and chromaticity measurements for quality control based on human perception.
- Evaluate augmented projections generated by HUD systems from conventional 2D HUD systems to 3D and AR-HUDs.
- Leverage tests to evaluate the optical performance requirements of laser-based HUDs, DLP projection-based HUDs, TFT display-based HUDs, and more.
- Measure absolute luminance and chromaticity in projected images.
- Test image clarity, distance, and position; characterize image distortion, warping, ghosting, and other effects.
- Use with a Radiant ProMetric Imaging Colorimeter or Photometer (16, 29, or 43MP) with 200 mm lens.