See the gallery of stimuli.
This data set contains the measusrement of the psychometric function. The function describes how the probability of detection (y-axis) is related to the physical contrast of a stimulus (x-axis). The stimulus is a 9 cpd grating.
The blue crosses on the plot represent measurements, the red continous line is the fit of the psychometric function (Eq. 17 in the HDR-VDP-2 paper), and green circles are the prediction of the visual metric.
The data was reproduced from: Nachmias J, Sansbury RV. Letter: Grating contrast: discrimination may be better than detection. Vision research. 1974;14(10):1039-42.link; Figure 2, data 9 cpd grating, observer CS, open symbols curve (detection).
This is the revision of the metric described in detail in the paper "HDR-VDP-2: A calibrated visual metric for visibility and quality predictions in all luminance conditions" (doi). It shares many similarities with VDP'93 and HDR-VDP, as it was inspired by these metrics, but the functionality is much extended and individual components are thoroughly revised. Note that the model parameters for this revision are different than the parameters included in the supplementary materials of the paper. Refer to the project web-page for the latest code and parameter values.
Revision 2.1 fixes an important bug that caused the nCSF to remain fixed below 1 cd/m^2. To extend the operational dynamic range, the CSF was measured at additional luminance level of 0.002 cd/m^2. The CSF was also measured for all observers, resulting in a more accurate CSF function fit. The predictions are improved for majority of data sets.