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Evaluating the Quality of Head-Up Display System Projections

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Manufacturers face unique measurement challenges with Head-Up Displays (HUDs). They must be accountable for contrast, projected image luminance, and clarity, irrespective of virtual image positions, ambient conditions, or focal distances on an infinite viewing plane.

Complete HUD testing requires photometric (light data) as well as dimensional (spatial data) measurement combined to guarantee the precision of data sent to a vehicle operator within a quickly changing, real-world setting.

The TT-HUD module is part of the Radiant Vision Systems TrueTest™ Software series. It offers all the advantages of the TrueTest™ Software to competently perform color, light, and dimensional measurements with particular tests used to assess the quality of augmented projections, such as those produced by HUD systems.

A complete HUD test solution from Radiant Vision Systems integrates the TT-HUD application-specific software module, and a ProMetric^® Imaging Colorimeter or Photometer with 200 mm electronically-regulated lens to carry out quick, automatic visual inspection of HUDs.

The TT-HUD uses a ProMetric^® imaging system to test all HUD features concurrently, capturing and processing data relatively faster and more reliably than a machine vision system or spot measurement device, alone or combined. In a single hardware/software system, the TT-HUD can be used to assess all visual features of the HUD system and to test to the precise parameters documented in automotive standards:

SAE J1757-2 “Optical System HUD for Automotive”
SAE J1757-1 “Standard Metrology for Vehicular Displays”

Supported Products

ProMetric^® I Series Colorimeters: I16, I29, I61
ProMetric^® Y Series Photometers: Y16, Y29, Y43, Y45, Y61
ProMetric I-SC Solution: I61-SC

System Requirements

ProMetric® Imaging Photometer or Colorimeter (16 megapixels or higher) or ProMetric I-SC Solution
Windows® 10, 64 bit
16-32 GB RAM
Additional system requirements vary by camera.

Comprehensive HUD Test Suite

HUD quality tests comprise photometric measurements used to assess the properties of light (contrast and brightness) and also spatial measurements used to assess projection quality (warping and distortion) against fixed tolerances.

The TT-HUD enables users to establish a full set of measurement parameters and pass/fail criteria for all points of interest within the HUD test images. In addition, the software module consists of standard display tests, as well as dedicated tests and test images for optical HUD assessment including:

ANSI Brightness
AutoPOI
ANSI Color Uniformity
Checkerboard Contrast
Chromaticity
Compare Points of Interest
DFF Image Sticking Analysis
Diagonal Checkerboard Analysis
Distortion 9 Point
Distortion Dot Grid
Distortion Line Grid Analysis
Eyebox
Field of View
Ghosting Analysis
Image Export
MTF Line Pair
Particle Defects
Pixel Defects
Points of Interest
Sequential Contrast
Uniformity
Virtual Image Distance
Warping Analysis

Based on the TrueTest™ Software test sequencing system, users can add tests from the TT-HUD test library to a sequence. These sequences are stored, so that numerous sequences can be developed and recalled as required. Furthermore, test parameters and pass/fail settings may be set for each test to generate qualification criteria specific to each manufacturer’s needs. The whole sequence can be worked automatically from end to end. Individual test results are shown and can be saved in a report.

Image Distance and Location

If the TT-HUD is used in the Focus Mode, this will allow users to effortlessly calculate the real distance of images in the projection at different focal distances on the infinite plane.

Exploiting the electronically-controlled lenses of Radiant ProMetric^® imaging systems, the TT-HUD software changes camera focal distance to real distance units to compute the exact image location as projected out to more than a few meters. This is particularly important for establishing image clarity and sharpness at different focal depths, like in the case of AR-HUD systems where images may be projected at a variety of distances.

Fully-Automated Testing

Since TT-HUD offers the same functional competence of Radiant Vision Systems’ TrueTest™ Software platform, a Radiant HUD measurement system includes TrueTest™ software API to modify interfacing and communication with the HUD system.

API can be used to regulate test images transmitted by the HUD system, activate the connected imaging system (ProMetric^® Imaging Colorimeter or Photometer) to capture a measurement image, and synchronize the defined TT-HUD test in sequence for fully automatic testing. This comprehensive system integration provides unsurpassed efficiency for testing optical quality factors of the HUD projection system within minutes.

Multiple System Configurations

TT-HUD can be used with a ProMetric^® Imaging Photometer or Colorimeter, offering numerous options to realize the field of view, color measurement, dynamic range, pixel resolution, and cost requirements for the user’s application.

The TT-HUD is supported by Radiant Vision Systems’ worldwide support staff and distribution network. It is field-proven and has been used to analyze the optical quality of HUD systems for top brands around the world.

Key Features and Highlights of the TT-HUD Module:

Pre-defined tests can be rapidly applied for cutting-edge HUD measurement
Software test sequencing and API device integration can be realized to regulate display test images along with software analyses, allowing automated production-level testing
Users can apply tolerances and acquire pass/fail data to achieve in-line quality control
It supports the standard requirements of the Society of Automotive Engineers for HUD methodology (SAE J1757-2) and optical measurement (SAE J1757-1)
Single test suite records chromaticity, luminance, and dimensional measurement data for analysis
Data analysis operations such as isoplots, bitmaps, and cross-sections

Typical Applications

The TT-HUD allows assessment of the optical quality of virtual images projected by HUDs, with absolute chromaticity and luminance measurements for quality control based on the perception of humans.

Image distance, clarity, and position can be tested; image distortion, ghosting, warping, and other effects can be characterized.
Augmented projections produced by HUD systems can be evaluated from 2D traditional HUD systems to 3D and AR-HUDs.
Absolute luminance and chromaticity in projected images can be measured.
Tests can be leveraged to assess the optical performance needs of laser-based HUDs, TFT display-based HUDs, DLP projection-based HUDs, and more.
Use with a Radiant Vision Systems’ ProMetric^® Imaging Photometer or Colorimeter (16MP and higher resolutions) with a 200 mm lens.

Evaluating the Quality of Head-Up Display System Projections

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.

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.

Image Distance and Location

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.