![]() ![]() We also provide a discussion of practical difficulties of evaluation of resolution in electron microscopy, particularly in terms of its sensitivity to data processing operations used during structure determination process in single particle analysis and in electron tomography. Within this framework it becomes straightforward to describe the connection between the outcome of resolution evaluations and the quality of electron microscopy maps, in particular, the optimum filtration, in the Wiener sense, of the computed map. ![]() We point out that the organizing principle is the relationship between these measures and the Spectral Signal-to-Noise Ratio of the computed density map. Here we provide description of standard resolution measures commonly used in electron microscopy. Instead, resolution measures in molecular electron microscopy evaluate consistency of the results in reciprocal space and present it as a one-dimensional function of the modulus of spatial frequency. When the amount of detail in the computed density map is low there are no external standards by which the resolution of the result can be judged. Considering 30% Contrast, we may find up to 80 LP/mm of resolution.Resolution measures in molecular electron microscopy provide means to evaluate quality of macromolecular structures computed from sets of their two-dimensional line projections. As a side note, there are smaller elements of grain on analog film as well, but due to their amount and the bigger elements, their contrast gets lower and lower. Studying the relation in between MTF and lenses and sensors for a while and doing post-production with various materials, my personal opinion is that any motion picture resolution above 30 LP/mm is needed only if you aim to do clean signal sampling and make the pixels disappear. Even when you'll look at specs for really high-resolution cameras and lenses, you seldom find anything above that. Interestingly, many charts for lenses nowadays cover the same two points: 10LP/mm and 30 LP/mm. However, I think it is fair to consider that in ideal productions up to 30 LP/mm ended up to be resolved. Of course, we need to consider some of the issues using analog film like the somewhat variable back focus, copies of the film losing resolution and so on. If you consider the green channel as being most important, then the film's resolution with 50% contrast would be about 50 LP/mm. Small highlights tend to shift their color towards yellow as the blue color component lost contrast starting at 10LP/mm, staying above 50% ratio until about 35 LP/mm. Reading it, the contrast value in the MTF chart reduces dependent on spatial frequency and depending on the color. There are detailed specification data available for the resolution of this film stock, and we can find MTF charts in the technical specifications. One of the best analog film stocks used in many motion picture productions was the Kodak Vision 3. No one is questioning we need this kind of proper sampling (up to 48 kHz) or Oversampling (up to 192 kHz) in the world of audio, so why are so many people questioning it in the world of video? In the world of motion picture or video, though, it is even more challenging because of the ability to appear for the quantization in multiple directions (x- and y-axis and diagonal directions). In the world of audio, we use sampling frequencies like 44.1 kHz, 48 kHz, 96kHz or even 192 kHz for a signal that should reproduce up to 20kHz -the limit of what we can hear- accurately. As an example of how important this kind of proper sampling is, we can think about audio sampling frequencies. ![]() ![]() Those are the Nyquist-Shannon theorem or geometric challenges like curves or edges close to the horizontal or vertical axis. Those errors appear if we don't take important factors into account. Otherwise, we will face spatial quantization errors. In order to reproduce any given analog spatial resolution, we need to have a digital spatial resolution (sampling frequency) that is significantly higher. ![]()
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