Bear in mind the photos will usually be viewed on a 1080p phone screen which is ~2MP. Or a 4k display which is ~8MP. The sensor has been getting bigger since the 6s which means more light for each pixel.
Camera pixels are not like screen pixels, more like screen subpixels. Each one has a color filter in front in a Bayer pattern, meaning a 2MP screen more closely corresponds to a 6MP camera sensor than a 2MP sensor. Respectively a 4K display already goes to 24MP camera sensor equivalency, which is quite a lot - many of the modern full-frame cameras have 24MP and more than that is considered high-resolution.
He does have a point in that a 12 MP CMOS sensor will have 12 million sensor elements, not 36 million. Colour filters are placed in front of each pixel, so RGB data can be extracted. Usually, 1/4 of the pixels are R, 1/4 are B and 1/2 are G. The raw sensor data for each pixel thus contains either R, G, or B, of varying intensities, depending on the passbands of each filter. The data is combined using a demosaicing/debayering filter/algorithm to extract subpixel data. That is, surrounding colour information is combined so that each pixel has R, G, and B elements.
Sorry if the writeup isn't that specific, I mostly work with monochrome CMOS cameras.
edit: I should also state that I don't know anything about iPhone cameras. It's quite possible, but not typical that they have a 36 MP sensor producing 12 MP images.
edit 2: I read that the iphone 12 has 1.7 um pixels. A 36 MP 4:3 sensor with 1.7 um pixels would be 8.3 mm. A 12 MP 4:3 sensor would be just 6.8 mm wide.
no the sensor has rows of 4000 grayscale pixels with different color filters on them. the actual rgb resolution is actually a quarter but the debayering algorithm upscales the data by 2x in each direction. So yes the RGB resultion is the same as the subpixel resultion, but at the same time it isn't.
You're correct. The numbers that are promoted for just about any camera out there refer to the actual size of the output, not the number of elements in the sensor. I'm not sure where the parent comment was getting his info from.
The actual size of the output is not the actual size of the sensor. The color data is interpolated. The promoted size is the output size, but that's not really full subpixel resolution in the monitor sense.
The promoted size is the number of photosites on the sensor, but each photosite is grayscale. Look at any RAW camera format or the datasheet of a sensor (e.g. one of popular Sony sensors). All of that applies to Bayer sensor and not Foveon, but Foveon is not particularly popular by any measure.
I've played with a friends Samsung S21 Ultra 108 MP and it blows out of the water my iPhone 12 Pro Max, provided you can keep it stable - portraits were insanely realistic, yet I was unable to capture a single photo of my toddler!
Even during the megapixels wars, Fuji released some great point and shoot cameras that had less megapixels but better image quality due to having a bigger sensor.
For example, the f31d was great in its time and showed that megapixels weren't the only measure to look for.
Oh, I give the iPhone a ton of credit. It generally looks good enough, the HDR on video makes shit look better than reality, the low-light performance beats the absolute pants off of anything else I own by a _huge_ margin.
I bought an iPhone 12 Pro pretty much entirely as a camera to use to capture a bunch of photos of my kid because (1) I don't have my DSLR within arm's reach in the house all the time and (2) our house isn't very well lit. I have zero complaints about it. I probably take photos with my iPhone versus my actual photo gear at least 20:1, if not more.
The photos look great on a phone screen.
But even just printing a 4x6 photo from the iPhone and a 15 year old DSLR and putting them side by side, the difference is immediately obvious. The iPhone photos are disgustingly oversharpened while somehow being weirdly smoothed, but in all the wrong spots.
I grabbed a couple of my own photos taken on the same day in the same place under largely the same lighting conditions (it's never exact) and zoomed/cropped them to help demonstrate and for privacy. Neither have been adjusted at all (I did try and improve the iPhone photo best I could, but really managed no substantial looking improvement so posted it as-shot), so focus more on the definition in the hair: https://imgur.com/a/7bn8W5S
See if you can guess which came from an iPhone 12 Pro, and which came from a Nikon D70 (about a $100 camera body at this point).
That all said, the entire point was... expecting anything more than 12MP out of an iPhone is absolutely pointless because the sensor size and optics simply aren't there to actually produce a better photo.
>the difference is immediately obvious. The iPhone photos are disgustingly oversharpened while somehow being weirdly smoothed, but in all the wrong spots.
Not sure what is going on with your comparison crop. The phone photo seems to actually be out of focus in the relevant area, not to mention overexposed.
There is some good cheap glass, but I am not aware of any good $100 glass.
I also assume that 6mpix camera has to be quite old, and that means that computational photography in iPhone 12 wrt dynamic range will be vastly superior.
In any case "infinitely better" sounds like a big stretch. Can you share some examples?
The main issue, as far as I understand it, is that the tiny sensor and tiny lens at some point just end up limiting the effective resolution. You can capture more pixels, but you never really increase the actual effective resolution of the end product. At that point you're not accomplishing much more than scaling up a lower resolution picture.
The "computational photography" usually ends up just vastly over-doing the sharpening and creating artifacts, and leaving weirdly smooth gaps where there was nothing to sharpen but the camera completely failed to pick up detail.
Just a couple random photos I grabbed from a day I took my kid to the park, but not necessarily like... scientific-paper worthy examples: https://imgur.com/a/7bn8W5S
One's taken with my iPhone 12 Pro, one with a Nikon D70.
Mainly, though, I base this off of trying to print any of the photos I've taken, and maybe someone else can hop in and explain this for me. I could be way off base here.
Printing photos from my iPhone at 4x6 they all look like someone took a really soft or slightly out-of-focus photo, applied way too much sharpening, and printed it. Printing a photo from my D70 generally still looks crisp and natural. Even if I blow it up beyond the actual resolution, it looks pixelated... not soft and then sharpened. This is even though the iPhone has twice the resolution of the D70.
Maybe we should measure resolution in TV lines per image height instead of pixels. It sounds like an archaic measurement but then all the clever processing tricks and dodgy pixel counting wouldn't hide the true resolution.
It matches my experiences too, FWIW. I've never seen anything out of a phone come close to my ancient D90 with f/1.8 35mm lens - with the caveat, for things that the f/1.8 is good at, portraits mostly.
The computational composition (I wouldn't call it photography) done by modern phones also just looks weird. For example, trying to detect foreground and artificially blur the background, leaving a weird in-focus-yet-distant halo of texture around things.
"Infinitely better" is the problem. My d7100 and z5 take amazing pics. They are also the only option for anything requiring zoom. But, for snapshot style pics the iPhone 12 Pro is great, particularly in challenging light situations.
In studio light situations, fstoppers did a video years ago that had the iPhone (6 maybe?) produce pictures that rivaled the dslr at the time.
It's simply more complicated than infinitely better.
Not the person you’re responding to, but lenses don’t improve image quality. All optics have some defects, and high quality lenses will have fewer of them. But a larger, more expensive lens primarily allows for a wider range of aperture and greater control of depth of field. That does allow for more artistic photographs, but objective image quality does not improve.
If you’re still skeptical, consider a pinhole camera with no lens capturing an image at near infinite focus. Adding a piece of glass that refracts the light can’t perform any better than pure parallel rays of light.
Bigger lenses mean more light. More light means better signal to noise ratio. That's an objective metric of image quality.
Phone cameras can try to compensate for this by taking long exposures - actually videos - and warp the frames into alignment to remove blur, but it's a losing game if there's a lot of motion. Or the camera can try and guess the textures and replace them with similar ones, like the Gigapixel AI and similar services do - but then it's starting to move away from capturing the actual scene.
I mean, most of the photos I take are with my phone, because it's the handiest available camera. I don't think people talking about quality from dedicated cameras are trying to say that they're better than phones as a practical tool for taking everyday photos. But you do lose some quality and computational tricks can't get it all back.
Because it is a big claim. And there are many different kinds of photographs you can take in many different situations, so something what is an advantage in one situation is a disadvantage in another.
Computational photography can overcome some of the optical limitations of the small sensor. E.g. you need a really good camera to get the dynamic range that is available with iPhone HDR.
Old camera (I am not aware of any modern cameras having 6mpx sensors) is an old camera. Cheap glass is a cheap glass. The bigger the sensor the better your lens has to be optically, because light is bent at the bigger angles.
The two most obvious areas (ergonomics and interchangeable lenses aside) of advantages of the "proper" cameras with bigger sensors are low-light performance and "bokeh". Otoh, if you want to have as much in focus as possible small sensors win.
No. No matter if you have wide-angle lens or the telephoto lens, you still need to cover the whole sensor with the image and the distance from the last glass element of the lens to the focal plane does not differ that much.
For two sensors of the same resolution (= number of photosensitive cells), a physically larger sensor will have a greater number of photons hitting each photosite. This means better signal-to-noise ratio (fewer photons = base electrical noise is greater in relation to the signal) and dynamic range.
So inescapably, due to basic laws of physics, for two identically implemented sensors of the same resolution, the larger one will always be better.
This doesn't mean you can't make miniscule sensors with 41MP -- you certainly can. There can even be advantages to doing so. The Nokia PureView cameras were based on a novel concept that by capturing very high resolution images (41MP) you can then smooth out the noise (because it is essentially random) while retaining huge amounts of detail if you downsample them to a reasonable size (something like 12MP? I forget what it does exactly) in post-processing. It is a tradeoff -- you trade worse dynamic range for better detail -- but it worked really well for a smartphone at the time.
If you were to pixel peep the 41 MP files before downsampling they would look horrible, especially at higher sensitivities.
> For two sensors of the same resolution (= number of photosensitive cells), a physically larger sensor will have a greater number of photons hitting each photosite.
Nitpick: this assumes that you're holding the f number constant. In practice smaller sensors tend to be used with smaller f numbers, which somewhat offsets the effect (especially if you are not someone who's given to shooting everything wide open on your DSLR).
A more useful way to think about it is to forget about the sensor and just consider the absolute diameter of the aperture (for a given angle of view). Your phone's aperture is a few mm in diameter. If you're shooting at the same angle of view with your DSLR, then the amount of additional light hitting its sensor (as compared to the phone) is in proportion to the additional diameter of the DSLR's aperture. So if you're shooting at, say, f16, you may not be getting any more light than the phone is at f1.8.
> Nitpick: this assumes that you're holding the f number constant. In practice smaller sensors tend to be used with smaller f numbers, which somewhat offsets the effect (especially if you are not someone who's given to shooting everything wide open on your DSLR).
Well most phone cameras seem to be around f/2, some slightly above, some a little below. The archetypal nifty fifty is f/1.8 or f/2 as well, and primes in that range are usually available for most applications and reasonable in price. Slightly slower primes at f/2.8 are often also available and cheaper. So dit-for-dat, you'd expect a full-frame camera to have at least 6 EVs lower noise than your average 1/3.something inch phone camera sensor (crop factor of ~10, area difference of ~100, ld(100) = 6...).
Your entrance pupil metric is really just a roundabout way to compensate for the crop factor of the sensor to get to the same FoV. The relevant property for exposure is the f-stop.
F-stop is the relevant property for exposure, but not for the total amount of light collected by the sensor, which is what determines the noise level (all else being equal). Exposure is light per unit area.
I do think that focusing on sensor size is unhelpful when thinking about noise levels. Big sensors do not magically collect more light simply in virtue of being bigger. They can only do so if you’re able to put a bigger hole in front of them (again, holding constant the angle of view). The use of very wide apertures is inherently more practical with smaller sensors.
As for using wide apertures with a DSLR, this is of course possible, but only in cases where a shallow depth of field is acceptable. On a cell phone camera f1.8 will almost always give sufficient depth of field. Realistically speaking most photos on a DSLR will be taken a few stops down from that.
It’s undoubtedly the case that DSLRs have an advantage over phones in terms of noise levels, but you have to consider the whole optical system to estimate the magnitude of the difference, not just the size of the sensor.
I had a Nokia 808 PureView with a 38MP camera and a real flash, you were able to save the full 38MP jpg and the quality was really good for the time in daylight, but it performed badly in low light and saving the picture was slow at 38MP.
I wouldn't try to keep a full pixel array in main memory when it is so limited. I'd keep the image in storage and decode as needed. It's a lot of software work to implement a special decoder and you'll always face a significant performance penalty, but it's doable.
I'd suggest playing with such camera before commenting. Maybe it doesn't matter for day to day point and shoot, but you can capture insane pics with 100MP sensor.
For a long time it was very easy to advertise cameras by the number of megapixels, and consumers supposedly like easy to understand numbers where bigger is better. This used to be kind of true back in the day of <6MP but raw megapixel numbers have been fairly useless for fifteen years or so.
It's a slow process moving away from this once you've drilled it into people's heads with marketing. It's just like how MHz used to be an easy and fairly reliable way to compare CPU's in the 90's and it took a really long time for the general public to understand that clock speed isn't all that matters.
I’ll take that a step further and contend Apple wants to do away with advertising technical specs: resolution, speed, capacity, etc should be good enough that users just don’t care to know. At that point, most customers shy away from competition because the tech numbers are incomprehensible or deceptive.
I'm looking forward to further movement of the market in that direction. Some products aren't the centerpiece of your life and you want it to just work without consuming your mental effort. Enthusiasts can still read the spec sheets or reverse-engineered estimated spec sheets if it comes to that, but normal people can get on with their life.
I don't know the storage capacity or resolution of my phone, nor the engine size of my car because they're good enough.
It's not easy to qualitatively represent your fancy HDR algorithms and focus finding, especially in the realm of phones where there are fewer standard terms to play with (even something as simple as OIS means nothing to 99% of buyers)
That's why you see a focus on showing off the end results now, like Apple's rebooted "Shot on iPhone" campaign or Samsung's current photo competition restricted to photos taken with a Galaxy S21
That's at a 16:9 video ratio though. There are no phone camera sensors out there with a 16:9 ratio. That would be useless for taking still photographs.
Most DSLR/mirrorless cameras have a 3:2 ratio, whereas smartphone cameras tend to have a 4:3 ratio.
If you want to make a smartphone camera sensor that can do 3840 pixels across that can shoot 4k, the 4:3 sensor would need to be 2880 pixels tall. So 3840*2880 = 11.1MP would be the bare minimum size for a smartphone camera that can shoot 4K.
In practice you'd want something larger than that, so you can do DCI 4K (which is a bit higher resolution) and do things like gyroscopically assisted electronic image stabilization (which benefits from a few extra pixels around the border). The iPhone can probably implement video stabilization that rivals GoPro's HyperSmooth stabilization.
I've never personally seen that resolution used, nor called "4K". If you're going to lump together a resolution with 50% more pixels under the same umbrella term then IMO "4K" is meaningless and we need more granular terminology.
