Identification of military targets and simple laboratory test patterns in band-limited noise
conference paper
We investigate the effect of band-limited masking noise and blur on the minimum contrast required to identify a) military targets, b) the standard MRTD and MTDP four-bar test pattern and c) the TOD equilateral triangle test pattern. First, the image containing the test object was spatially blurred by an amount varying from one pixel up to the maximum blur at which the object could still be identified or resolved. This mimics the effect of sensor optics and detector blur on the image of a target at different ranges. Then, band-limited noise was added to the image. The center spatial frequency fc of the masking noise was varied over 7.0 octaves. Observers had to indicate at which target contrast they were just able to identify the target. The results are a) identification thresholds for all targets are strongly elevated by masking noise of certain spatial wavelengths and much less by coarser or finer noise, showing that identification by human observers is mediated by a relatively narrow visual filter, and b) with increasing blur, maximum masking shifts towards lower noise spatial frequencies in a consistent but non-linear way. Current popular TA models are inconsistent with these results but suggestions for improvement are presented. The laboratory test patterns are appropriate to characterize target acquisition performance with viewing systems that include noise and blur.
Het effect van ruis of de identificatie van militaire doelen en eenvoudige patronen werd onderzocht. Uit het onderzoek blijkt dat het visueel systeem slechts struktuur van een beperkte reeks groottes gebruikt voor identificatie, dit is anders dan tot nu toe aangenomen en heeft consequenties voor de doeacquisitie.
Topics
Contrast thresholdMRTDNoiseNVThermTarget acquisitionTODCamerasCharge coupled devicesImage sensorsLaboratoriesOptoelectronic devicesSpeech intelligibilityContrast thresholdMRTDNVThermTarget acquisitionTODOptical sensorstarget acquisitionnoiseNVThermcontrast thresholdmilitarythermal imagingtriangle orientation discrimination (TOD)minimum resolvable contrastminimum resolvable temperature difference
TNO Identifier
13168
Publisher
The International Society for Optical Engineering
Source title
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XV
Editor(s)
Holst, G.C.
Place of publication
Bellingham, WA., USA
Pages
104 - 115
Files
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