Talk:Optical transfer function

Uncited Section

The section “Factors affecting MTF in typical camera systems” makes a lot of sweeping statements without any citations. I think this section should be marked as needing citations. I tried to read the documentation on how to do that but didn’t understand it. Perhaps someone more experienced can place that tag on this section. — Preceding unsigned comment added by 73.31.163.83 (talk) 13:39, 27 March 2022 (UTC)

Question copied from article

Someone wrote a question into the article, i removed it there and copied it here -- 84.190.192.91 17:30, 23 January 2007 (UTC)

This page looks like it has been lifted from a larger article. For example, the following sentence appears "The OTF accounts for aberration, which the limiting frequency expression above does not." but there is no previous refrence to a "limiting frequency expression". Please explain what this is.

The MTF definition presented appears to be inconsistent with standard usage. For situations where the object space input phase varies randomly from point to point (i.e., non-coherent imaging), the MTF is the normalized Fourier tranformation of the convolution of the point spread function with itself.

Doh!

I'm sorry, but I regard myself as a reasonably intelligent person and have been told by many people that I am regarded by them as highly intelligent. So what the blazes is going on here? I turned to this link from the "Spy Satellites" article and instead of an explanation found a highly technical article which requires a great deal of prior knowledge on the subject at hand. As you may assume, I don.'t have that knowledgebase and therefore found the article less than useful. Indeed, I walked away less clear and decidedly more frustrated.

Please don't think I am being insulting to the author/s in any way, I am merely conveying my personal experience as best as I can. In my own experience I know it can be far too easy to be too close to one's work and not realise one is unintentionally leaving folks behind. And as an encyclopedia is an 'everyman' sort of reference, I feel this article needs further work, perhaps with a clear mind to it being a Wikipedia article and not a technical reference work of the field thus making it possible for the lay person to understand.

Thanks and kindest regards,

Outofthewoods (talk) 08:42, 23 November 2010 (UTC)

I agree this is an overly technical article with no non-technical introduction. I didn't see it linked from spy satellite. This page needs love, but it is intrinsically technical as opposed to say image resolution; the page that linked you here should probably link there or somewhere similarly less-technical. —Ben FrantzDale (talk) 12:38, 23 November 2010 (UTC)

I regard myself as an expert in this area, having worked on the development of ccd cameras and image conversion for many years. So I have re-written from scratch. Hope this meets with approval. -Lindosland (talk) 11:20, 25 April 2011 (UTC)

It's still quite technical. It could probably be improved with a visual example or two. 216.118.216.42 (talk) 19:35, 6 July 2011 (UTC)

I am a retired physics teacher and degree holder in technical imaging and this article is just total rubbish. I've known about and used the concept of MTF in all sorts of fields, including professional telescope mirror making, for over 50 years, yet this would have to be the worst technical article on Wikipedia. Condescending, impenetrable and useless for someone seeking to understand the basics of MTF, let alone understand the usage of it as an everyday tool in so many fields to do with optics, radio frequency transmission and information technology generally. No introduction to the wave theory of light, nothing. Typical of nerds who know a bit about technology, except how to teach. Useless. — Preceding unsigned comment added by 203.212.129.70 (talk) 08:16, 28 November 2016 (UTC)

WP:SOFIXIT. Dicklyon (talk) 08:35, 28 November 2016 (UTC)

Mystery term in equation

One of the equations in the "advanced" section introduces a mystery term λ(ξ,η) apparently defined nowhere else in the article-- this needs a definition, or the equation is simply baffling, rather than informative. -- The Anome (talk) 21:37, 4 February 2012 (UTC)

I guess the λ-function returns to the phase shift in wavelengths of each spatial frequency component. The PTF is simply OTF/MTF, as is clear from the above, so I replaced the λ-function with the more commonly used complex argument and added a little explanation. (Tom.vettenburg (talk) 21:11, 7 October 2012 (UTC))

Measuring the OTF

The paragraph "Measuring the OTF" discusses the gratings necessary, but not how to measure the OTF. The only hint given is that the OTF is the Fourier transform of the Point spread function. — Preceding unsigned comment added by 91.32.113.96 (talk) 11:40, 30 July 2012 (UTC)

Merge from Modulation transfer function (infrared imaging)

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was to merge the MTF (infrared imaging) article into the OTF article. Tom.vettenburg (talk) 13:45, 25 December 2013 (UTC)

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Someone suggested merging these two articles over a year ago. It seems obvious as nothing on Modulation transfer function (infrared imaging) is really infrared-specific. Is there any reason not to merge these? —Ben FrantzDale (talk) 13:37, 6 May 2013 (UTC)

MTF (modulation transfer function) is a standardized method to measure the sharpness and contrast of a lens, so that different lenses can be evaluated and compared. reference: http://photographylife.com/how-to-read-mtf-charts — Preceding unsigned comment added by 70.26.255.41 (talk • contribs)

MTF is not limited to infrared, but applies to optics designed for any wavelength, and is predominantly used to compare camera lenses.

Here are some sites that use and discuss MTF data to compare lenses: dpreview.com , imaging-resource.com, http://photographylife.com/how-to-read-mtf-charts , dcresourcel.com with an example of MTF charts on this page http://www.dcresource.com/forums/showthread.php?23055-400D-70-200-4-IS-and-50-1-2-L

Here is an EXPLANATION OF MTF - Modulation Transfer Function http://photographylife.com/how-to-read-mtf-charts and this is supported by other online documentation as well. Just to give a few examples: http://photo.net/learn/optics/mtf/ http://www.kenrockwell.com/tech/mtf.htm http://www.normankoren.com/Tutorials/MTF.html

Also, there is an infrared-specific reference on this page https://spie.org/x34304.xml which looks similar to the infrared-specific MTF page posted on wikipedia.

The current web page on wikipedia needs to be corrected/replaced with the correct information, that is not specific to one type of equipment, but rather, gives the true definition of MTF. (ie: tire performance is not just on dirt track - tire performance can pertain to a tire's performance on any surface). — Preceding unsigned comment added by Timmbits (talk • contribs)

Yes, please do merge it. Dicklyon (talk) 05:52, 25 May 2013 (UTC)

• Support - The article 'Modulation transfer function (infrared imaging)' is not specific to infrared imaging and actually shows how to calculate the Optical Transfer Function of a digital image of a line or edge target. I merged this under the section headings Optical_transfer_function#Numerical_evaluation and Optical_transfer_function#Using_extended_test_objects_for_spatially_invariant_optics. Tom.vettenburg (talk) 12:46, 8 November 2013 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Removed lines from More Advanced Details section

1. For correctness I removed the final line on Scanning Electron Microscopy as it has no optical transfer function:

In the case of the Scanning Electron Microscope (SEM), the electron detectors do not capture the phase of the electrons, and, therefore, the PTF can be disregarded, leaving the MTF equivalent to the OTF.

Although it certainly can be regarded to have a transfer function, electrons, not photons lie at the basis of its functioning. Furthermore, the term PTF (phase transfer function) refers to the complex argument of the optical transfer function, not the phase of electrons (or photons). For example: an asymmetric spot in SEM would have a non-zero PTF. — Preceding unsigned comment added by Tom.vettenburg (talk • contribs) 17:59, 18 August 2013 (UTC)

2. Similarly, the following line was removed from that section:

Phase is critically important to adaptive optics and holographic systems.

The phase in PTF is not the same phase as that corrected in adaptive optics or used in holographic systems. While both are optics related, and could be used to correct the OTF of aberrated systems, these are much broader concepts not specific to the PTF or OTF.

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These removals make absolutely no sense. 1. OTF/MTF is applicable to all wave phenomena. It does not care whether the wave is a gravity wave on water, or it carries W-bosons, electrons or photons. 2. If the wave is spacially-modulated at a certain frequency, the phase of OTF has exactly the same meaning as the phase of the incoming wave (both w.r.t. dependence on space and/or time). When the phase of OTF is rotated 45°, the phase of the wave would be rotated by exactly the same angle. --Ilya-zz (talk) 02:37, 7 September 2021 (UTC)

Addition of general theory and examples - towards a merge with Modulation Transfer Function (Infrared Imaging)?

Currently, it seems that the most developed part of the article is that explaining the relationship between optical transfer function and sampling (pixel resolution). At present, many important aspects are barely touch up on. Some are covered in the modulation transfer function article, though this seems to rather specific on infrared imaging and certain techniques of determining it. Neither article does give much detail on the theory, and only one example is shown of a modulation transfer function, none for the optical transfer function. A more general article, covering the important aspects with theory, examples, and applications would require some restructuring. I started working on that in my sandbox and welcome any comments. For now I just adapted the introduction and included a figure with examples of the optical transfer function.

Tom.vettenburg (talk) 00:32, 4 November 2013 (UTC)

I merged most of the MTF article contents in. The only subsection missing is that describing its calculation. Currently this concentrates on how to calculate the discrete Fourier transform numerically from the line spread function. This is certainly not the only method, and I think we can rewrite it to be more general, hence I left it out for now.

Tom.vettenburg (talk) 00:29, 5 November 2013 (UTC)

film

This article has some description of the OTF/MTF of an optical system imaging on film, but nothing about the film itself. Film data sheets give the MTF for the film itself. Since film can't resolve phase (except in holography), it is MTF instead of OTF, but the article claims to do both. Gah4 (talk) 08:17, 6 December 2018 (UTC)

References

distance or spatial frequency?

It seems to me that resolution should be specified as a spatial frequency, and not as a distance. At one point the article says it could be said that its resolution is 2 μm, though mostly it seems to use spatial frequency. I suspect that this goes back to WP:RS which probably often enough get it wrong. But for high resolution to have the right meaning, it needs to be spatial frequency. Gah4 (talk) 01:57, 6 December 2019 (UTC)

The plots are extremely confusing

The plots of MTF/OTF stop at the cut-off frequency, as if there no MTF/OTF above this point. This leads to a lot of confusion: very often people get an impression that “something may happen above this frequency” — it is just not written explicitly. It is very important that these plots must be extended by 0 to the right of the cut-off frequency!

(In fact, it is clear why the plots are constructed this way: the text — many times — mentions the point where the graph reaches 0, and it is much easier to see this point if “something abrupt” happens there. But this “abrupt” change may be a color change!)

It would also be nice if the text would reiterate at all suitable points that MTF/OTF is zero above the diffraction cut-off frequency for every optical system…. --Ilya-zz (talk) 02:19, 7 September 2021 (UTC)