2

I have a Xiaomi Mi A2 Lite with 2 cameras on the back:

  • 12 MP (PDAF) Aperture size: F2.2; Pixel size: 1.25 μm
  • 5 MP (Depth information) Aperture size: F2.2; Pixel size: 1.12 μm

Most of the time I use it to get pictures of descriptions/prices labels in shops, but if I take several together, they are often not easily readable or look moved.

I see now they sell smartphones with 64MP or 3 cameras but what should I really look for? What should I look for most in my next phone?

Glorfindel
  • 1,128
  • 1
  • 11
  • 21
wlf
  • 121
  • 4
  • 1
    I also had a lot of smartphone images which were blurred. That's due to the long exposure time in dark environments. Megapixels don't help. You could use the flash, but that might give bad reflections. If you don't use a flash, note that turning the brightness might increase exposure time. Instead you could leave it quite dark and then work on the image on PC. Some camera apps have a "Pro" mode where you can decide whether you want to increase ISO instead of exposure time. If you take the picture very close up, the camera might not be able to focus. There's really a lot that can go wrong. – Thomas Weller Feb 03 '22 at 06:13
  • 1
    I had a Nokia 7250 which could do that. Steady hands and knowledge of light levels is enough, even with old sub-megapixel equipment. – Stian Feb 03 '22 at 10:27
  • Can you use a tripod and mount a selfie-type light for better illumination? – Steve Feb 04 '22 at 16:57

4 Answers4

14

It's not really a case of how many megapixels you have - 12mp is plenty just for a product label - it's whether you can get enough light onto the label for the exposure to be short enough that you can hold the camera still for long enough that the image doesn't blur. To be legible, a label doesn't need to be perfectly sharp, just 'sharp enough'.

This crop of a sauce bottle label is 1/10th of a megapixel

enter image description here

That was reduced from the original image of about 1 megapixel, but is still just about legible. Almost as an accident of how this page renders images, this shows at about life size compared to the original bottle label.
Here's the full size image…

enter image description here

This should now appear on the page as larger than life.
To the left is a slight reflection, caused by my not paying sufficient attention* to how the light was falling & making that one part shiny. Too much of that & you will lose legibility. It's also not perfectly sharp, but I was trying to get something 'real life' rather than 'perfect'.

*accidentally on purpose;)

Tetsujin
  • 23,252
  • 3
  • 46
  • 97
  • 3
    HP brown sauce? – spikey_richie Feb 02 '22 at 11:34
  • 4
    Is there any other? ;)) – Tetsujin Feb 02 '22 at 12:31
  • Thanks. Most of the time I have to take several labels (in a reasonable amount) on several shelves at the same time. I try to get the right light on the labels and to keep my hand as steady as possible but what should I look for most in my next phone? MP, multiple lenses or the camera software? – wlf Feb 02 '22 at 13:37
  • 2
    'several labels on several shelves' doesn't really give us a sense of scale at all. If you need to do this for a job or many multiples of times, then you might be better off with a dedicated camera. Can't really say until we can see an idea of what it is you're doing. – Tetsujin Feb 02 '22 at 14:04
  • 1
    "this shows at about life size" - that depends on the screen you're reading this on. On my 27", it certainly looks larger! – Jonathan Feb 03 '22 at 08:02
  • @Jonathan - OK, it depends on your dot-pitch, or if you're on HiDPI, virtual dot-pitch. On a regular 27", it's about the right size, also on a retina screen iMac. On a phone, it's likely smaller;) – Tetsujin Feb 03 '22 at 08:23
  • I would say the OP actually has too many pixels, and those are too small. I have idly wondered about creating a smartphone camera app supporting software binning, i.e. adding 2x2 (or a larger square of) sensor pixels into a single output pixel, displayed and captured. 4x4 binning would work with 12MP to start with, giving 16x the sensitivity when you don't need the resolution. With the sensitivity of modern sensors, that would be a nice low-light camera. This wouldn't be as good as hardware binning of course, but that's not an option on consumer CMOS sensors anyway. – Chris H Feb 03 '22 at 15:40
8

I edited your original question with one question you posted as a comment.

what should I look for most in my next phone?

Nothing.

What you need to control is your photo technique. If that is what you do on a regular basis, spend some time perfecting your process.

they are often not easily readable or look moved.

If they look moved is because you moved during the shoot. So you need to learn how to configure your camera to prioritize a good shutter speed, and a good technique holding the camera for the purpose you intend.

Ok. Probably there are some things you could look for on a new phone for this. An excellent low light performance. Search for this: https://www.google.com/search?q=best+low+light+phone but the phone costs several times more than the current one you have. But if you do not really learn how to use your phone you will get the same results.

if I take several together

Ok. Again. Learn the limitations of your gear. How many are several? Are you standing on the other side of the store? or you mean 2 or 5. Take time to know your subject and the photo techniques, including distances. A readable text does not need even 1 Mpx, but if what you framed is the entire store... Even quadrupling your Mpx may not be useful.

You could also look for additional light like https://www.google.com/search?q=Clip-On+Lighting+for+Phones but you will now have a problem with reflections on the label, which, again is solved with a good technique and knowing your scenario.

Take a lot of test shots in your home. Put the groceries on a table and practice turning lights off, on, next to a window, far from it... practice.

Rafael
  • 24,760
  • 1
  • 43
  • 81
  • 5
    +1 Any phone or camera from the past twenty years will be more than capable of taking perfectly legible photos of product labels. – J... Feb 02 '22 at 19:38
  • 1
    @J... at home, I have in fact used a VGA webcam for something similar, back when my cameras wouldn't shoot tethered or produced oversize files without post-processing. With decent lighting of course. – Chris H Feb 03 '22 at 09:07
  • 1
    I'm with @ChrisH -- I'd photographed shelf tags and product labels going back to an old flip phone with 1/3 megapixel. The main limitation was how close I could get and stay in focus. – Zeiss Ikon Feb 03 '22 at 15:31
  • 1
    “a good technique holding the camera for the purpose you intend” — this is very important, especially when the light isn't very bright. It can be very hard to hold it still without moving enough to blur the image over a long exposure. One technique I find helpful is to brace the camera firmly against something solid such as a wall or shelf. (Even if the framing is slightly off, you can fix that by cropping/rotating afterward; but you can't fix blur.) – gidds Feb 03 '22 at 16:43
  • @gidds of course phones as cameras might as well have been designed to make this hard. If there's nothing solid to brace against, at least hold with 2 hands, upper arms against ribs, and pause breathing for the shot (more of a record shot tip than one for top quality photos of course) – Chris H Feb 04 '22 at 09:01
  • As well as being expensive, good low light cameras in phones tend to restrict your other options (for me, waterproofing is an absolute requirement, also ruggedness and ideally not too massive). I accept a rubbish camera on my phone, but have a selection of dedicated cameras. They're all old, but the PowerShot SX200 IS from 2009 would work a treat here, even without flash – Chris H Feb 04 '22 at 09:12
2

Take care to hold the phone/camera still. Don't wave it about with one hand, while holding the product with your other hand.

  • Hold the phone/camera with both hands and steady yourself.
  • Ensure the camera is focusing on the text. Don't hold the camera too close.
  • I find that I get best results by additionally using a 3-second self-timer.
  • Check results and take another photo if necessary.

Summary - basic photo technique is what's required here, not a different phone.

osullic
  • 12,093
  • 1
  • 23
  • 47
1

Your issue is the poor hand-holdability of a smartphone combined with a ridiculously small sensor size.

It's darker indoors than what you think. Indoors in typical light, the light level is less than 1/100 of the light level in daylight outdoors. So you need to collect 100 times more of that faint light indoors than outdoors.

One possibility is a fast aperture. Because smartphone cameras have fixed focal length lenses, you can have easily f/1.8 as opposed to f/4. The trouble is, this gives you only 5 times more light than a typical f/4 zoom in a digital SLR or mirrorless camera.

So you need something more. One possibility would be raising the sensor sensitivity. However, small sensors can't be sensitive without having huge amounts of noise. Unfortunately a smartphone camera has 1/38 the area of a full frame camera. So this can't be done: smartphone cameras are 1/38 times as sensitive as full frame cameras.

You could use a flash (Xenon tube flash to be precise). The trouble is, practically no smartphone has a flash. Some Nokia PureView phones did but you can't buy those anymore. Typically the thing called "flash" is a LED light. The trouble is, it helps only in very very dark environments. In typical indoors environments, the LED light won't create a brighter scene than the light that is already there.

So the only remaining possibility is increasing exposure time. That's what your phone is doing indoors. Unfortunately, because the phone doesn't have a proper hand grip like good cameras, but instead is a flat piece, you can't keep it steady. Especially because it lacks a shutter button, you need to touch the touchscreen to take a picture, vibrating the camera phone and thus taking a shaken picture.

The best solution is buying a phone with image stabilized camera. Usually the image stabilizer is so good that more than two thirds of your pictures are very sharp.

Without an image stabilizer, you probably need to take 50 pictures. Maybe if you're very lucky there might be one sharp picture among those 50 pictures.

So it isn't about megapixels. It's about image stabilizers.

juhist
  • 6,740
  • 16
  • 51
  • A phone's LED can do a really good job in typical indoor lighting if photographing something like paper at modest range. A bigger issue is glare from shiny things. Some phone camera apps allow for a short delay after pressing the shutter button (CameraMX has 3s or 10s. I'd prefer 1s). You can also trick this if autofocus is turned on, which it should be, by focussing on/shooting something a very different distance away then quickly moving to the real subject and shooting. Some phones/apps allow mapping volume keys to operate the shutter. That can help a little if they're very sensitive – Chris H Feb 04 '22 at 09:06
  • @ChrisH Or you can take a video and then take a screenshot. – Acccumulation Feb 04 '22 at 16:27
  • @Acccumulation not really. Screenshotting a video leaves you with an image at the screen resolution, which may not be enough to read text. Extracting a frame is possible but tedious, and signal-to-noise is usually far worse than on a still, if light is low. Some phones/apps have a burst mode that would work well – Chris H Feb 04 '22 at 16:35