Why image stitching?

Modern ultra-wide displays (e.g. with an aspect ratio of 21:9, 32:9, or 6:1) push conventional measurement systems beyond their limits. The sensor area is used inefficiently, while resolution is insufficient. With LMK Image Stitching (part of the display package), TechnoTeam provides a powerful extension for high-resolution luminance measurement of displays with large or unusual aspect ratios. Several individual images are merged into one seamless, high-resolution overall image, without any loss of measurement accuracy.

How LMK Image Stitching Works

Multiple images are captured and combined into one continuous luminance image. The core of the process is our Advanced Pixel Registration (APR) method:

  • Separation of position detection and luminance measurement: Ensures distortion-free, pixel-to-pixel mapping.
  • Direct measurement in display coordinates: No post-processing or geometric adjustments required.

The result: a robust, precise, and efficient solution for large-area or slightly curved displays

For even greater efficiency, the stitching process can be fully automated in LMK Position, our robotic measurement system. Combined with TechnoTeam’s short-distance uniformity correction (external link to our technical article), this automation ensures perfectly consistent results and eliminates potential waviness artefacts, making high-precision luminance stitching not only faster but also more reliable in both lab and production environments.

Your Benefits at a Glance

  • Higher resolution by combining multiple captures
  • Greater efficiency through optimal utilization of sensor area
  • Accurate fusion thanks to pixel registration with APR
  • Cost savings by using an LMK with any resolution
  • Scalability from laboratory setups to fully automated production environments

 

APR Technology in Detail

  1. Registration image: Exact localization through targeted activation of display pixels
  2. Luminance test image: High-precision luminance measurement.
  3. Stitching: Merging of multiple images directly in the display coordinate system.

Basic concept of image stitching: individual measurements are combined to form one result image

APR method and luminance measurement (top) are merged into one pixel-precise luminance image (bottom)

RELEVANT PRODUCTS AND APPLICATIONS

LMK Position

LMK Position

Automation & Precision: Luminance camera with 6-axis robotics
LMK BlackMURA

LMK BlackMURA

Add-on for low-frequency uniformity measurements
Automotive Display

Automotive Display

Publications

International Conference on Display Technology (ICDT 2021)

The alignment quality and reproducibility in ILMD (Imaging Luminance Measurement Device) based display metrology has a great influence on the reproducibility of the obtained measurement data. In this context, this contribution outlines and introduces several advanced measurement and alignment concepts that can be performed with “photometric robotics”. The term describes machine vision performed with an ILMD supported by robotic movements.
Authors: I. Rotscholl; B. Liu ;U. Krüger
Advanced Alignment and Metrology Concepts Using Photometric Robotics with Examples for Automotive Displays

SID Vehicle Displays & Interfaces 2022

As head-up displays play an increasingly important role in modern vehicle cockpits, there is a growing demand for measurement procedures to characterize them. There are two general approaches to measuring virtual image distance, a parallax-based triangulation method and a focus-based technique. They can be performed using Imaging Luminance Measurement Devices with type II calibration, making them suitable for photometrical and geometrical measurements. This paper examines the advantages and drawbacks of both methods using mathematical models and measurement data.
Authors: A. Voelz; I.Rotscholl; U. Krüger

Journal of the Society for Information Display

The increasing display sizes and changing form factors of displays, including automotive displays, lead to impractical measurement distances for lateral uniformity measurements. This contribution suggests and exemplarily applies two alternative and combinable methods to allow lateral uniformity measurements at low distances and describes an adjusted BlackMURA compliant validation procedure. The proposed methods are validated with a high-quality display device and are compared to results using the standard long-distance measurement procedure.
Authors: I. Rotscholl; U. Krüger
Distinguished Paper: Short Distance Uniformity and BlackMURA Measurements

SID Vehicle Displays & Interfaces 2021

The increasing complexity of automotive displays in terms of design, shape, and degree of integration leads to an increasing complexity of setup and alignment procedures. In this context, the effort required to ensure reproducible measurement results, e.g. for prototypes or in research and development is also increasing rapidly. We introduce the concept of photometric robotics which combines machine vision, photometry, and robotic to solve these challenges.
Authors: J. Adams; I. Rotscholl; U. Krüger
Type:
Software