It’s possible to test all sorts of displays, including flat panels, projectors, heads up displays (HUDs), virtual & augmented reality head-mounted displays (HMDs) using Imatest charts & software.
1. Display a test chart pattern on your screen
A vector graphics test pattern, such as one generated by the Imatest Test Charts module can be rasterized using Inkscape to match the native display resolution, then shown at 100% magnification in an image viewer on the display. The Screen Patterns module can be used to display a test pattern directly from Imatest.
For sharpness & resolution tests, we recommend checkerboard patterns which will keep the edge transitions unaffected by aliasing.
For specific details about blemish, defect pixel detection and uniformity tests see: Testing display defects with Imatest Blemish Detect.
2. Capture a high-res image of your display
Using a high quality calibrated reference camera should take a picture of your display or projector. In order to verify display resolution, the reference camera should have several times the pixels density compared to the pixels on the display so that the fine details and defects within the display are resolvable.
For displays where the individual RGB color pixels appear at different spatial locations, If a reference camera with a sharply focused lens has a pixel size on the object (the screen, or virtually projected screen) which is not significantly smaller than the individual color sub-pixels of the display, the captured image will suffer from color moiré which will affect measurements.
3. Analyze the captured image with Imatest
If the reference camera is able to resolve the individual R/G/B sub-pixels, then this can disrupt the calculation of spatial resolution measurements such as Slanted-edge SFR. The “more settings” window of most Imatest Modules has a “channel” selection which can be set to “Mean (R,G,B) “ which will smooth out the edge function compared to the default Luminance channel pixel values which favor the green channel.
At this point, the performance of the display the reference camera) can be tested using a range of Imatest modules.
Ideally, MTF units should be expressed in Line Widths per Display (Monitor) height. A procedure for doing this is given in Camera Monitor Systems. Quick summary: measure the monitor height in pixels in the camera image. In the settings window (shown on the right for SFR; similar settings are available for other modules), select MTF plot units of 12. LW/N Pixels (PH) and enter the measured monitor height in Picture Ht (pxls). MTF plot units will be equivalent to LW/Monitor Height.
This page needs to be updated with:
- Process for measuring dynamic range & contrast ratio
- ISO 16505 — Road Vehicles — Camera Monitor Systems
- Testing display defects with Imatest Blemish Detect
- Camera Monitor Systems are of increasing interest in the automotive industry. Display (monitor) sharpness (MTF) can be measured in units of Line Widths (LW) per N pixels, where N is the height in pixels of the monitor image in the second camera’s image. This is equivalent to Line Widths/Monitor Height.