What is slanted edge method?
The slanted-edge method specified in ISO 12233 measures the MTF as a function of the horizontal or vertical spatial frequencies of digital image acquisition devices by analyzing the image data in a user-defined rectangular region of interest (ROI) in an image of a knife-edge target captured by the device.
Why slanted edge mtf?
The slant edge method is a widely used MTF estimation method, which can effectively solve the aliasing problem caused by the discrete undersampling of the infrared focal plane array.
What is modulation transfer function of the optical system?
The Modulation Transfer Function (MTF) is a measure of the ability of an optical system to transfer various levels of detail from object to image. Performance is measured in terms of contrast (degrees of gray), or of modulation, produced for a perfect source of that detail level.
How is MTF measured?
In practice, MTF can be measured by presenting a series of sine-wave targets of increasing spatial frequency to the system under test, and then measuring the contrast in the corresponding image patterns. Plotting the ratio of image contrast to target contrast against spatial frequency will then produce the MTF curve.
How is MTF value calculated?
MTF(u) = C'(u) / C(u). C is the contrast in the target, C’ is the corresponding contrast in the image. For low spatial frequencies the MTF is nearly 1.0 or 100%. The curve then generally falls as spatial frequency increases, until it reaches zero, the limit-of-resolution for the lens.
How do you measure MTF on a lens?
The most direct test of MTF is to use an object that consists of a pattern having a single spatial frequency, imaged by the Lens under Test. The operator measures the contrast of the image directly. This is a discrete- or single-frequency measurement. Discrete frequency measurement methods are commonplace.
How do you calculate MTF on a lens?
What is MTF lens?
Modulation Transfer Function or “MTF” is a measurement of the optical performance potential of a lens. MTF charts can give you a better understanding of the optical quality of various NIKKOR lenses, and can be useful references when researching, comparing and purchasing a lens.
How is MTF lens measured?
What is a good MTF value?
Generally, contrast will typically be higher than resolution in MTF charts, so anything higher than 0.9 indicates excellent contrast, between 0.7 and 0.9 is generally very good, between 0.5 and 0.7 is average and anything below 0.5 is soft / bad.
What is a lens MTF chart?
A MTF chart plots the contrast and resolution of a lens from the center to its edges against a “perfect” lens that would transmit 100% of the light that passes through it. The contrast of a lens is important as this works in correlation to lens resolution.
Is higher MTF better?
In general, the higher and flatter the lines the better. Higher lines indicate better contrast (10 lines/mm) or resolution (30 lines/mm) while a flatter (left to right) line shows that the optical performance is close to the same at the edge of the image compared to the center.