Software artifacts: noise reduction and sharpeningSoftware (especially operations performed during RAW conversion) can cause significant visual artifacts, including oversharpening "halos" and loss of fine, low-contrast detail. These artifacts result from nonlinear signal processing (so-called because it varies with the signal). These artifacts can be measured by the Log F-Contrast module in Rescharts, which analyzes the chart shown on the right, which varies logarithmically in spatial frequency on the horizontal axis and in contrast on the vertical axis. |
Original | NR+Sharpening  |
Images may be sharpened (MTF boosted) in the presence of contrasty features like edges and blurred (lowpass filtered) in their absence. This generally improves measured performance (both sharpness and noise/Signal-to-Noise Ratio (SNR)), but it may result in a degradation of perceived image quality, for example, a "plasticy" cartoon-like appearance of skin even though edges are strongly sharpened. This loss of detail cannot be measured with 
