Single display pixels are used to evaluate the resolution
The LMK Display Resolution software is part of the display add-on package. It provides two algorithms that calculate resolution parameters based on high magnification measurements. It is used to characterize “loss of sharpness” or perceived resolution. It measures the resolution capability of the display, (which includes the complete light propagation through the display stack) based on the display’s input signal resolution.
The software package consists of two algorithms: Pixel Crosstalk and Slanted Line MTF. We recommend them for different applications.
Pixel Crosstalk
The pixel crosstalk measurement evaluates the resolution by analyzing the scattering profile of individual display pixels in horizontal and vertical direction. Both directions are measured simultaniously and in the complete field of view. During the measuring process, first, an image is taken in which all pixels are switched to dark. This image serves as correction image to account for the display backlight or other effects. Then, individual pixels or subpixels are turned on and High Dynamic Range measurement images are taken for each test image. The software automatically determines all pixel positions and calculates the horizontal and vertical "Pixel Crosstalk values" for red, green, blue, and white pixels in percent.
The fundamentals of the evaluation algorithms are based on the publication "Pixel Crosstalk: A New Metric to Characterize DOI Loss Due to AG Treatments of Display Glasses" by Thomas Fink und Udo Krüger.
- Suggested Applications: Virtual images (Head-up-Displays or Near-Eye-Displays)
- Sampling conditions: A sampling ratio above 30 camera pixels/display pixel is recommended to allow neglection of resolution decrease caused by the lens.
- Limitations: The algorithm cannot be used on displays with an irregular subpixel layout, such as pentile structures. Here we suggest to use the LMK Resolution: Slanted Line MTF instead.
Slanted Line MTF
Slanted Line MTF is a fast way to measure the resolution capability of a display in a single shot as a function of all input frequencies. The method bases on the well-established slanted edge evaluation, which is used to characterize the MTF (Modulation Transfer Function) of optical elements such as lenses. During the measurement, the LMK is slightly rotated axially relative to the display. The display shows a single line or row with a width of 1 pixel or subpixel. A luminance image is captured using a High Dynamic Range measurement. After correcting for background and the impact of the MTF-calibrated LMK lens, the display MTF is obtained from the luminance image and evaluated for all frequencies below two times the display's Nyquist frequency.
The fundamentals of the evaluation algorithms are based on the publication "Line-Based Modulation Transfer Function Measurement of Pixelated Displays," by Kenichiro Masaoka.
- Suggested Applications: Direct view displays with and without additional layers (e.g. anti-glare layer, cover layers, decor elements ...)
- Sampling conditions: We recommend a sampling ratio above 10 camera pixels per display pixel. In addition the field of view of the camera should not crop the luminance profile of the slanted line
- Limitations: The algorithm should be used with care for virtual images. Here other aberrations such as distortion, can falsely affect the MTF slanted line resolution result.
A slanted line with a with of one display pixel is used to evaluate the resolution
High-magnification macroscopic lenses with an optical magnification between 0.5 and 2 are required for standard displaypixel sizes, e.g. in smartphones or laptop displays. For very small display pixels, such as, e.g., micro displays, microscopic lenses with a magnification between 5 and 50 are available as well. For Near-Eye-Display resolution measurements special NED lenses wiith a small field of view are recommended. For more information on the measurement and evaluation algorithms, including a more detailed comparison of both methods, please have a look at our related publications.
DISPLAY PACKAGE
This add-on is part of the display package add-on. It can be ordered separately or in combination with the other display add-ons.
The other display add-ons are linked below.
Downloads
Publications
Invited Paper: Reproducible Characterization of Microdisplays using Imaging Luminance Measurement Devices (ILMDs)
International Conference on Display Technology (ICDT 2024)
In this contribution, we present typical practical implications of high magnification lenses required for camera-based microdisplay measurements and analyze their impact on existing measurement methods for DeMURA, resolution and contrast. Furthermore, we show hardware and software-based methods to improve or handle the shortcomings of these high-magnification lenses.
Reproducibility Evaluations and Calibration Sensitivity of Slanted Line Display MTF Measurements in Oversampling Conditions
International Display Workshop (IDW 2023)
In this contribution we research calibration related impacts on MTF measurements using the Slanted Line approach in oversampling conditions. Based on this we propose a simplified workflow of the Slanted Line MTF method and conclude benefits and limitations of these setup conditions.
Resolution Capability Measurements: A Comparison Between MTF Slanted Line and Pixel Crosstalk
Society for Information Display 2023
In this contribution, we qualitatively and quantitively compare the recently proposed slanted line MTF resolution measurement with the established pixel crosstalk resolution measurement. This is done by comparing evaluation results and reproducibility from measurements of nine different samples in three different setups for each method.
Reproducibility and Sensitivity Experiments of Display-MTF using ILMDs with Fixed Focus Macroscopic Lenses
Eurodisplay (2022)
This contribution uses the recently proposed Slanted Line approach to evaluate the MTF of a display as a measure of display resolution. It investigates the sensitivity for macroscopic imaging conditions and compares the reproducibility between four different macroscopic lenses using three different ILMDs. The samples consist of two displays combined with different structured top layers, which negatively affect the perceived resolution of the displays.
Pixel Crosstalk: A New Metric to Characterize DOI Loss Due to AG Treatments of Display Glasses
SID International Symposium 2016
A method is proposed that characterizes the loss of image clarity caused by anti-glare coatings. The method uses high resolution imaging, giving a distribution of scattered light that can be related easily to the clarity impression of the human eye. Results of different AG treated cover glasses are shown and a new parameter is proposed to characterize the loss of image clarity. This can be applied to the specification and characterization of the cover glasses as well as the characterisation of the final product for quality assurance.
Image Blurring Induced by Scattering Anti-Glare Layers
SID International Symposium 2016
We introduce the scattering-induced spreading of a narrow linear light source in transmission as an alternative method for characterization of image blurring induced by anti-glare layers. This novel method is compared to the recently presented concept of pixel crosstalk and to the transmissive scatter distribution function of anti-glare layers measured in two different ways. The reduction of transmittance modulation is presented as an additional method for characterization of image blur. The ranking of the results is compared to a generalized haze level of the AG samples as obtained from the transmittance distribution functions measured with two different methods.
- Type:
- Add-On
- Applications:
- Automotive Display
- Measurands:
- Light measurement
- Tasks:
- Development & Industry