$$Ratio = \frac{\sigma_D^2}{\sigma_B^2} $$ where: $$\sigma_D^2 $$: variance of pixel values of the detail region on microparticle step $$\sigma_B^2 $$: variance pixel value of the background region on uniform step with same contrast as detail… Read More
$$Relative\ contrast = \frac{|\mu_D-\mu_B|}{\mu_B}$$ where: μD: mean pixel value of the detail region μB: mean pixel value of the background region… Read More
The visibility of details is determined according to the value of an IQI representing the visibility: CNR is used for large low contrast details DCC is used for small high contrast details A threshold is set for every group of details and if the value of the IQI is greater… Read More
First the MTF values for all available bar pattern frequencies are calculated. Then, the frequencies at a certain MTF level are calculated with a linear interpolation between the two nearest frequencies having a known MTF value. Read More
$$DCC = \frac{\sum_i{PCNR_i \cdot w_i}}{\sum_{i}{w_i}} $$ where PCNR (Pixel Contrast to Noise Ratio) is: $$PCNR_i = |GL_i-\mu_B|, \qquad \forall i\in D_i$$ and μB: mean pixel value of the background ROI… Read More
$$CNR = \frac{|\mu_D-\mu_B|}{\sigma_B}$$ where µD: mean pixel value of the detail ROI µB: mean pixel value of the background ROI σB: standard deviation of pixel values of the background ROI… Read More
Control charts represent the trend of a statistic inside the range of working values. Control charts are used to visualise the statistic over time and thus to have a clear idea of which are the trends. Furthermore, control charts have also a baseline vale, which is the “normal” value for… Read More