The MTF (Modulation Transfer Function) tells us about the acuity, or ability to resolve the detail of a system regardless of its resolution in terms of pixels. Thus, an image may have many pixels, but may not have detail due to lens effect, shaking, depth of field, etc.
The MTF can not only be used to quantify in absolute terms the sharpness of a system, but it can also be used to evaluate other circumstances such as loss of detail due to trepidation or depth of field.
To calculate the MTF we need a "sloped edge" chart
The boards show:
- MTF: indicates the MTF characteristic curve in cycles/pixel
- ESF: tells us about the "softness" of our edge, where it is also easy to highlight the work of focus improvement filters and the formation of "halos" during these processes.
- LSF: Shows the sharpness of the edge.
- C/p or Cycles / pixel
- Lp/mm o Even / millimeter lines
- Lw/Ph or Lines Width / Picture Height
- LPH or Lines Picture Height
The following metrics are displayed on the ESF board
- Misregistration o CA (Chromatic Aberration) It shows the registration error between channels R, G and B. This error is usually related to the events of chromatic aberration
- 10-90% Rise It indicates the slope of the ESF curve between 10% and 20% of intensity, which is usually taken with a more or less sharp symptom
Lp/mm, Lw/Ph and LPH metrics use the sensor data, such as its size and derived pixels, so they must be set in advance in the camera information panel.