Investigations of internal noise levels for different target sizes, contrasts, and noise structures

Minah Han; Shinkook Choi; Jongduk Baek

doi:10.1117/12.2042969

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11 March 2014 Investigations of internal noise levels for different target sizes, contrasts, and noise structures

Minah Han, Shinkook Choi, Jongduk Baek

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Proceedings Volume 9037, Medical Imaging 2014: Image Perception, Observer Performance, and Technology Assessment; 903715 (2014) https://doi.org/10.1117/12.2042969
Event: SPIE Medical Imaging, 2014, San Diego, California, United States

Abstract

To describe internal noise levels for different target sizes, contrasts, and noise structures, Gaussian targets with four different sizes (i.e., standard deviation of 2,4,6 and 8) and three different noise structures(i.e., white, low-pass, and highpass) were generated. The generated noise images were scaled to have standard deviation of 0.15. For each noise type, target contrasts were adjusted to have the same detectability based on NPW, and the detectability of CHO was calculated accordingly. For human observer study, 3 trained observers performed 2AFC detection tasks, and correction rate, Pc, was calculated for each task. By adding proper internal noise level to numerical observer (i.e., NPW and CHO), detectability of human observer was matched with that of numerical observers. Even though target contrasts were adjusted to have the same detectability of NPW observer, detectability of human observer decreases as the target size increases. The internal noise level varies for different target sizes, contrasts, and noise structures, demonstrating different internal noise levels should be considered in numerical observer to predict the detection performance of human observer.

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Minah Han, Shinkook Choi, and Jongduk Baek "Investigations of internal noise levels for different target sizes, contrasts, and noise structures", Proc. SPIE 9037, Medical Imaging 2014: Image Perception, Observer Performance, and Technology Assessment, 903715 (11 March 2014); https://doi.org/10.1117/12.2042969

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