Camera Resolution (Digital and Analog)

Discussion in 'Photography and Cameras' started by cizx, Sep 19, 2016.

  1. cizx

    cizx Friend

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    Analog doesn't have a bitrate or depth. Like a film doesn't have a resolution.

    Precision is another thing. Don't get bogged down in semantics.
     
  2. Madaboutaudio

    Madaboutaudio Friend

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    The best digital camera sensor's resolution is still limited by the performance of it's (analog) lens.
     
  3. cizx

    cizx Friend

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    Really? Are digital censors actually constrained by the clarity of glass? That's the bottleneck now? (Serious question)
     
  4. Madaboutaudio

    Madaboutaudio Friend

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    Yes, according to dxomark:
    https://www.dxomark.com/Reviews/Loo...r-DxOMark-s-Perceptual-Megapixel-can-help-you
     
  5. Kattefjaes

    Kattefjaes Mostly Harmless

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    Bad example, film -even slow, smooth film- has grain. This limits its effective resolution.

    Heck, diffraction issues have dogged them for ages- see also all the craziness with micro-lensing assemblies over the photosites.

    A lot of the valuable performance increases in digital sensors are more than just spatial resolution, stuff like noise performance is also critical. The smaller the photosite, the less light can hit it, so increasing spatial resolution means you need more gain, and thus thermal noise can be more apparent. Little consumer cameras can't usually have cryo-craziness on the sensors, so it's a war for SNR that you might find familiar.

    It's even worse with video, as your "exposure" time between shuttering events is constrained. I have used a 4Kp600 camera, and if you're doing full-bore 600fps with it, you need an awful lot of light to get good results (leaving aside the 13.something GB/sec of video that it produces).
     
    Last edited: Sep 19, 2016
  6. cizx

    cizx Friend

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    No. Wrong kind of resolution.

    Digital video has resolution like 1920x1080. Film does not. That's how they're making 4K transfers of older movies.
     
  7. TRex

    TRex Almost "Made"

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    100 MP sensor, anyone? https://www.phaseone.com/en/Products/Camera-Systems/XF100MP.aspx

    Determining film qualities (grain, resolution, etc etc) is insanely difficult. Film type, chemicals, lenses, timing; each affects the end result. Digital does have variables, but they are far fewer than film (there are hundreds of film developers, for instance).

    That being said, photography stuffs & audio are apples vs oranges.
     
  8. cizx

    cizx Friend

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    Only sort of. It's an attempt to capture infinite data with finite media. Digital or analog, you're not getting everything present in the original event.

    Again, academic.
     
  9. Kattefjaes

    Kattefjaes Mostly Harmless

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    Canon topped that years back :)

    http://cpn.canon-europe.com/content/news/120_megapixel_apsh_format_cmos_sensor.do

    If you want to cheat and use arrays, this is impressive, too:

    https://en.wikipedia.org/wiki/ARGUS-IS

    Yes, and if you'd actually worked with film properly, you'd know that when you scan it at a very high resolution, you get to see the grains. Film bores (I have been one, I recovered) obsess about grain structure and different development techniques that affect it, as well as how to simulate it well with reference to luminosity.

    The Root Mean Square granularity is how we express this grainyness. It's not a uniform comparison to sensor spatial resolution, as film grains vary in size and location is not predictable.

    If you're imagining that film has infinite resolution, you're simply wrong.
     
    Last edited: Sep 19, 2016
  10. Azteca

    Azteca Friend

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    Right. But if you made an 8K transfer of a film, then upscaled an identical frame from a 4K transfer, you'd find that there is likely no appreciable difference. Perhaps tiny differences in resolving the grain structure if you zoom in 20x. Now place that in the context of someone's home theater. Do they have an 8K screen and projector? What's their viewing distance? How bright is the room?
     
  11. Merrick

    Merrick A lidless ear

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    Film doesn't have a resolution like digital does, but it clearly has finite limits on the quality of the image it can reproduce. Things like the size of the frame, the amount of available light, the lenses mounted, the sensitivity of the film, shutter speed, the chemicals used, etc. can all affect the image. This is why digital cinema uses the term "equivalent" when comparing the resolution of digital to film. Some say 4K is the equivalent of 35mm, 8k is the equivalent of 70mm, somewhere between 16-20k may be the equivalent of IMAX 70mm, and so on.
     
  12. ultrabike

    ultrabike Measurbator - Admin

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    Moved this into it's own separate thread. No worries. Please carry on. :)
     
  13. Kattefjaes

    Kattefjaes Mostly Harmless

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    Aye, and even then, the information content of either varies based on the noise content. Obviously fast film, harsh development, and issues like reticulation dog film, but with a digital sensor, if it's too noisy, its useful resolution can be lower- if when used at full res, the noise is too apparent. I have seen stuff shot at 4k which could only pass tech review when downconverted to 1080p with some nice supersampling (this also prevented the use of 1080p crops being used for HD productions, annoyingly).

    It's all far more nuanced and complex than "analogue rools, digital drools", but then you knew that, and it should come as no surprise to any reasonably-informed adult.
     
  14. TRex

    TRex Almost "Made"

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    I think we need to determine what "resolution" is. Films do not have resolution in terms of pixels, but they do have power to resolve things. "Acutance" is probably the better word to compare digital & films.

    Digital: photons hit sensors which are constructed by tiny squares CCD/CMOS tiles (pixels) and create bitmap images. Physical.
    Film: photons hit a layer of silver halide and convert it. Chemical.

    Digital: information from sensors are recorded and converted to bits. Again, physical.
    Film: developing films is basically removing the excess and fixing (stabilizing) the silver content. Again, chemical.

    At the end, resolving power of films can't be converted to pixel resolution. The reason:
    1. I own an Epson document scanner. I have scanned many film prints (processed in darkrooms, not printer), 8" x 10". I created hundreds of megapixels scans from the prints, yet none surpasses sharpness of the prints (which are less 16-ish Megapixel according to various sources) even though I resize the Megapixel scan to 8" x 10". Even the best & most expensive film & print scanners can't capture 100% of print quality. Close, but not 100%.

    2. Digital grain reduces the resolution power, meanwhile film grain enhances resolution. Low-sensitivity films (such as Ilford Delta 100) have minimal grains & images from those films look smooth -not crisp- even though they capture even the tiniest details. The opposite happens on high-sensitivity films.

    TL;DR: films development & enlargement are mostly chemical process. Digital capturing & printing are mostly physical process. Thus film & digital "resolution" are completely different term. Both vinyl & digital media are physical. Thus films & vinyls are not comparable.
     
    Last edited: Sep 19, 2016
  15. Kattefjaes

    Kattefjaes Mostly Harmless

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    However, people have been characterising the resolving power of film for nearly 100 years, with varying degrees of success:

    https://books.google.co.uk/books?id=E45MTZn17gEC&pg=PA12&dq="rms+granularity"&lr=&as_brr=3&ei=vNe8SIODKYa4jgHw59TzBw&sig=ACfU3U0BZlbNUBLuhoh4cgdiYwA08xKVAA&redir_esc=y&hl=en#v=onepage&q="rms granularity"&f=false

    Again, it's nuanced, and requires some knowledge. Even the matter of digital sensors isn't quite as simple as most people imagine. They're not a regular array of full colour sensors, and after debayering, you get fewer pixels than there are functional photosites on the sensor.

    However, they are all things that can be quantified, and a suitably determined bore could compare them- you wouldn't need to be the ghost of Claude Shannon to pull it off.
     
  16. TRex

    TRex Almost "Made"

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    @Kattefjaes not only varying degress of success, the results are inconsistent. From these reasons, I personally believe that films don't have a fixed number of resolution. I agree that digital isn't simple. There are types of sensors (Foveon, bayer) and processes (algorithms, read-out signal, debayering, Anti-alias filter, etc.) but they affect acutance, not resolution. Resolution is determined by the number of individual pixels in the sensor. 16MP sensor in one camera can produce better result (acutance) than another 16MP sensor in another camera. From the same reason, DXOMark measures "PPix" (Perceptual pixel aka acutance),

    (Does anyone use iPad to post on SBAF? Since updating to iOS 10, sometimes the keyboard won't switch to symbols mode & sometimes it's laggy. iOS fault or not-optimized website?)
     
  17. Bill-P

    Bill-P Level 42 Mad Wizard

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    Film definitely has a "resolution". As in it can potentially capture certain information that a digital sensor may be unable to, due to various reasons... but let's look at it more in-depth:

    1) What the fudge is "megapixels"? It's simply the number of "micro light sensors" on the surface of a big sensor. Straight-forward. In audio terms, this would be the sampling rate. Bit-depth in audio term is the equivalence of color bit-depth in photography term. But just for clarity, while you can argue that for audio, 16-bit vs 24-bit doesn't produce a difference, with photography, it definitely freaking does. Professional cameras go up to 10-bit per color channel for a total of 30-bit. There is no "alpha" or "transparency" channel so no, that ain't the same as 40-bit color depth but technically, photography color bit depth exceeds the capability of most (if not all) consumer-level displays, and they even challenge professional-grade displays that are rated for 30-bit color depth. So no, audio vs photography in digital terms is not apples to orange. There are equivalences.

    2) What's "film resolution"? Well, it's the ability of a film to "retain information" that has been "burned on to it". Note that a film plane in photography term is literally an almost-exact "copy" of how light passed through the lens that was in front of it. In technical terms, it is indeed true that film that does not have a lot of noise (slow films in general) do in fact have a resolution that far exceeds whatever current digital technology can do, and that's why it still makes sense for some to scan films at uber resolution. Noise not withstanding because this "noise" on a film surface is due to various reasons... (Diffractions? Dust that got on the film surface during transportation?...) but just with pure "resolution" as the "amount of information captured" by definition, film definitely exceeds digital. This is still true when we are considering bad lenses. Why? Because even when a bad lens is used, that causes the image to be blurry, hazy, etc... say, for instance, if you "over-expose" a shot in photography, you can still recover a small part of the information by careful development of the film. For most digital cameras, recovering that over-exposed shot is pretty much impossible. If you don't have a camera with the absolute best sensor on the market, that does not "clip" information when over-exposed because you're an incompetent piece of shit, then your shot is simply gone. You have much more room for recovery when you're using film.

    3) So I would agree with the above that film and digital resolution are inherently different. This is more due to the limitations of digital technology, than because of anything fundamental.

    4) Digital "noise", going back on this topic, is actually due primarily to two very simple things:
    a - As said, thermal noise. When the sensor heats up (because photons are energy packets and they do kinetic shit), the micro sensors may record the wrong info, or do weird shit. Bigger cameras have better heatsink capabilities and all, but this is still a problem. You don't get this with film, by the way, obviously because film actually likes this thermal energy.
    b - Because the manufacturer of said digital gear cheaped out on the amplification circuit. Yes, you heard me right, an amplifier built in. High ISO in digital? That doesn't exist. A digital sensor technically only has "one level of sensitivity". Think... that a single digital sensor actually is the equivalence of only one type of film. This is why digital sensors have something called a "base ISO". Anything outside of this "base ISO" range is technically "simulated ISO", achieved through either boosting the lower signal received from the sensor through the mentioned amplifier circuit, or by doing some "Photoshop shit" within the firmware to boost the image. Guess why super high ISO (6400 and above) is so noisy? And why your camera's live view seems to lag when you activate this ISO range? That's because the CPU has to spend extra time "Photoshopping" each and every video frame for the preview.

    So when you compare ISO 400 or ISO 800 film to any random digital sensor, and find that film has more noise and shit, that's actually because the digital sensor in question is technically a ISO 100 or ISO 200 equivalence in film terms! Inherently, that's why talking about noise to compare between digital and film is useless, and already why people don't do so. RMS noise or whatever is stupid to talk about because, again... the digital sensor will be super dependent on the amplification circuit and the underlying software.

    So why is that the Sony A7S is now so universally praised for its high ISO capabilities and stuffs? Well, that's cuz Sony spent more time optimizing its built-in amplifier, so the amplifier has higher SNR compared to pretty much everything else on the market. A7Rii is beastly because it's basically that same circuit applied to a higher resolution sensor. Note how A7Rii is almost comparable to A7S all the way through to ISO 6400, and still with higher resolution? Going to higher ISO past 6400 will invoke software "gain" (that's what I call it) and then whether the photo has noise or not depends more on the CPU. I guess it's easy to see which one will be better, since it's faster to process 12MP vs 42MP.

    The world of photography is pretty much the same as that of audio. Only that it's all been measured and analyzed to death, and our eyes are far better at discerning differences and resolution compared to our ears... but in the grand scheme of things, if we wanna compare the two, the "similarities" are there. We just like to refuse things because we don't wanna believe more expensive shit makes sense... but honestly, sometimes they do. :p

    There are more beyond this... regarding why Leica is so well-liked and so on, but just briefly on digital vs film, it's pretty clear that there are advantages to both.
     
  18. purr1n

    purr1n Burned out

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    This is all semantics. With movies on 35mm film, the thought is that 4K is sufficient to capture everything, the grains, the plankton, without weird artifacts. Maybe on a good day with super fine grained film and ideal lighting conditions, 6K, another number I've seen thrown around for 35mm film. This of course doesn't mean the resolution (in terms of being able to make out horizontal lines) will be the same, real resolution will probably be a bit lower with film. Again it depends on the film and conditions. (What's really kind of scary is 70mm film is if you think about it. Keep in mind that 70mm film has 4 times for pixels than 35mm. That a lot more computer processing.)

    So film does have an effective resolution, just that's it's pretty high and only recent technology has been catching up to it. The DCP format (digital cinema package) used in the movie business is 12 bits. I think some of the consumer stuff is finally catching up in terms of bit-depth, but I'm sure most televisions purchased just a few years ago won't support the increased bit-depth.

    BTW, some Studios are archiving films on film media, even the digitally shot ones. They will separate CMY into three very high grained black and white film reels.
     
    Last edited: Sep 19, 2016
  19. Kattefjaes

    Kattefjaes Mostly Harmless

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    You have to be even more careful with actual acutance, and account for where it comes from.

    Anyway, making effective estimates of film's effective resolution is an accepted practise, luckily it doesn't require your permission or approval, as it has been a necessary part of media conversion and archival for years ;)

    http://videopreservation.conservation-us.org/library/estimating_historic_image_resolution_v9.pdf

    (It's less grisly than what's being done with D3 tape in the UK, at least..)

    Oh, and I haven't actually tried posting at all from my iPad- I need to get around to re-installing Keepass on it- usually I am just reading on it while listening to music. I haven't upgraded to iOS 10 yet, either, so maybe I should try before I do, just out of curiosity.
     
  20. TRex

    TRex Almost "Made"

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    @Bill-P I agree with your explanation (you're a far better communicatir than I am :headbang:), except of 2 points:

    1. Resolution/acuity & bit-depth. AFAIK, they are unrelared to each other. Bit-depth is the number of gradation of colors (i.e. From 100% black to 100% white).

    2. Resolution/acuity & over/underexpose recovery (dynamic range). They're two different things & not related to each other.

    Film grains, besides the films characteristics, is produced by many reasons. Agitation (particles rubbing film surface), developers/fixer (chemical composition). Dust on new films is rare.

    @Kattefjaes CMIIW, but I couldn't find any mention of the procedure. There are many lpmm numbers of films, yet I can't find how they determined the numbers.
     
    Last edited: Sep 19, 2016

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