6 ms·

The megapixel myth

47 points by henning 16y ago

stan_rogers 16y ago
While he's got the ratios right, he's got a tolerance for bad printing that I don't share. VGA for 4 x 6? Maybe if you thought your 110 Instamatic made good enlargements (in those days, 4 x 6 was a premium print). That's newspaper resolution. Double up the dimensions (1.2 MP) and 4 x 6 is just acceptable to my eyes (and it didn't used to be when printer dithering algos weren't what they are today).
- michaelhalligan 16y ago
  Agreed, with a 12 megapixel camera I never felt printing anything over 16 x 20 was acceptable, even with my 22 megapixel 5dmk2 I don't go much larger than 20 x 30.
  - jonah 16y ago
    It all depends on how closely you're viewing them. We have a bunch of photos shot with a 5D (12MP) printed about four feet tall. They look great from a normal viewing distance. Of course, when you put your face six inches away, you can start to see some digital artifacts (stair stepping, etc.) but that's not a problem. The maximum necessary resolution is related to the intended viewing distance. "The standard definition of normal visual acuity (20/20 vision) is the ability to resolve a spatial pattern separated by a visual angle of one minute of arc." From that the maximum resolvable dot size can be calculated for a given viewing distance. http://www.ndt-ed.org/EducationResources/CommunityCollege/PenetrantTest/Introduction/visualacuity.htm http://www.ndt-ed.org/EducationResources/CommunityCollege/Pe... http://www.clarkvision.com/imagedetail/eye-resolution.html http://www.clarkvision.com/imagedetail/eye-resolution.html (Sidenote: billboards usually printed at around 20-30ppi)
    - stan_rogers 16y ago
      20/20 is actually pretty bad eyesight. It's "normal vision", not perfect vision, and when my eyes are "corrected" to 20/20, they're about a quarter-diopter shy of maximal acuity. There is a huge difference to my eyes between pictures printed at a 200-line screen and one printed at a 150-line screen (all other things, like stock and varnish being equal) at a distance of more than one metre (from head-height on a couch to the magazine at the far end of a coffee table). If I were printing from a 12MP original at about four feet tall, I'd certainly run the source through something like Genuine Fractals Print Pro (even a good giclee pattern can't make up for squared-off curves). At four feet in the long dimension (giving a realistic viewing distance of about six feet) I'd notice raggedness at a glance at less than about 80ppi -- but then the dye clouds from a 4x5 negative printed at that size would drive me batty as well.
  - gaius 16y ago
    When you go to the cinema, you're looking at an image only 2000 pixels across.
    - deleted 16y ago
      [deleted]
cletus 16y ago
The article referenced this: http://www.nytimes.com/2007/02/08/technology/08pogue.html?_r=2&oref=slogin http://www.nytimes.com/2007/02/08/technology/08pogue.html?_r... The one company that seems to have a clue about this is actually Apple. The iPhone 4 has a 5mp camera in it. Some pundits say things like "I wish it had 8 megapixels or more". In doing so, they show their complete ignorance. Most people couldn't tell the difference between 5 and 8 megapixels. What 8 megapixels buys you is larger files, more noise and slower processing (on a sensor this small). The size of the pixels matter. It's one reason DSLR images tend to be so much better: they have hugely bigger pixels. I'd love to see more good 5-8mp point and shoot cams rather than these ridiculous 14+ mp noise factories.
- megablast 16y ago
  Well, to be fair, Apple have a different market to Canon/Casio/Sony point and shoot cameras. People aren't buying the iPhone 4 just for the camera. Apple still do deserve props for going for a better camera + lens, rather than the samsung route of more rez.
  - GFischer 16y ago
    Nokia, on the other hand, does sell a product specifically as a camera replacement: http://europe.nokia.com/find-products/devices/nokia-n86-8mp http://europe.nokia.com/find-products/devices/nokia-n86-8mp I bought the N86 because I realized I never have my camera when I want it, and I always have my cellphone (GPS was nice, but the killer app for me was the 8mp camera).
- ugh 16y ago
  Canon, Nikon and Panasonic reduced the number of pixels or kept them the same in their high end small sensor compacts. (Canon G11: 10 MP down from 14.7 MP in the predecessor; Canon S90 and S95: 10 MP; Nikon P7000: 10 MP down from 13.5 in the predecessor; Panasonic LX5: the same 10 MP as the 2006 model and a slightly bigger sensor.) The newest iPhone has a tiny 1/3.2" sensor, those high end compacts usually have 1/1.7" sensors, that’s quite a bit more than double the area. Their pixels are consequently a bit bigger. If Apple made the right decision Canon, Nikon and Panasonic must have, too. They get it and they know that at least their best informed customers (those who actually buy high end small sensor compacts) will also get it. They are probably only (unnecessarily) afraid of the general public, all those who buy the cheapo point and shoots. If you are willing to pay you get appropriate pixel densities.
celoyd 16y ago
The article’s heart is in the right place, but it overstates the case. For example, “Sharpness has very little to do with image quality, and resolution has little to do with sharpness” goes too far if you have a pretty good lens and you’re pretty good at avoiding camera shake. Pixel count is not nearly as important as marketing makes it out to be, but it is important.
seanlinmt 16y ago
If I'm not mistaken, the Mars Rover had a 1 megapixel camera. :)
- lutorm 16y ago
  Voyager had a .64Mp camera (800px^2)...
- jonah 16y ago
  Not only that, but it's a monochrome sensor with a filter wheel. It takes the same shot with multiple filters and the resulting images are merged back on earth. My friend worked on that project. [Edit] It has 12μm x 12μm pixels whereas the 5D has 8μm and the 5DmkII has 6μm pixels. However each pixel on the Canons contain three (RGB) photosites to the rover's one. http://www.mwoa.org/Ch31.pdf http://www.mwoa.org/Ch31.pdf
  - Tamerlin 16y ago
    No, the Canon sensors also have only one photosite per pixel -- they're still using a Bayer filter on a monochromatic sensor.
    - jonah 16y ago
      Ok, here we're getting into confusion about terminology here. To clarify: In the Bayer filtered Canon CCD each individual photosensor is covered in a colored filter [1] in a pattern such as: B G G R So when capturing an image 1/4 of the sensors are capturing blue light, 1/4 capturing red, and 2/4 capturing green. In contrast the CCD in the rover's cameras do not have filters in front of individual photosensors. Instead, there is a set of filters on a disc which are mechanically positioned in front of the sensor. Using this method three images are taken. On each with a red, green, and blue filter covering 4/4 of those same sensor elements giving you 2x-4x the number of elements capturing each color and thus much higher image quality at a given resolution. B B B B then G G G G then R R R R Similar multi-shot technology was used in the early days of terrestrial digital photography to provide better color, exposure latitude and resolution. [2] for a bit of discussion on multishot vs. single shot medium format digital camera backs. [1] http://en.wikipedia.org/wiki/Bayer_filter http://en.wikipedia.org/wiki/Bayer_filter [2] http://www.luminous-landscape.com/reviews/cameras/h3d50ii.shtml http://www.luminous-landscape.com/reviews/cameras/h3d50ii.sh...
lutorm 16y ago
Not to mention that most of those tiny cameras with huge pixel counts don't have optics good enough to resolve those pixels, so they really are pointless.
aaronsw 16y ago
Are Ken Rockwell and Lew Rockwell related? They seem to share a web designer.
gaius 16y ago
I used to work for... A press agency you've all heard of. We had lots of big prints up about the place. Now, some of these were shot on films like Fuji NPZ (ISO 800 colour negative) or first-generation photojournalist DSLRs (e.g. Nikon D1H, 2.1MP). At 60x40", they looked great. Nikon knew this; their second generation was "only" 4MP (D2H). What matters in resolution is lp/mm; that is how many distinct pairs of black and white lines can fit within 1mm. See here: http://www.bobatkins.com/photography/digital/size_matters.html http://www.bobatkins.com/photography/digital/size_matters.ht... The long and the short of it is, unless you are shooting on a tripod with a cable release and a prime lens, there's really not much point worrying about megapixels. I once had a huge row with people on a mailing list about this; try as I might I couldn't make them understand the simple idea that it doesn't matter how many pixels you have if they can't all be assigned distinct values, there's no additional resolution there. They were the kind of people that bought the most expensive DSLR and stuck the cheapest lens on it. Then again if you'd spent 5 grand on a camera and someone did the maths for you you might be upset too... ;-) Also note that cinema is only 2000 pixels across.
- pedrocr 16y ago
  lp/mm is just a unit of measure for resolution and is directly constrained by the number of pixels. You can't resolve 10 lines with less than 20 pixels and in practice you need more. The article you quoted compares the same resolution in different sized sensors to show that smaller sensors need to resolve more lp/mm in sensor area to achieve the same file in the end. It shows that for the same MP count a larger sensor is better. What we are discussing is the opposite, for the same sensor size MP count is better. And as far as resolution is concerned that tends to be the case, even if the lens is the biggest bottleneck. In DSLRs we're getting to a point where resolution is more constrained by camera movement and lens quality than number of pixels but at the same time both those bottlenecks are being addressed with modern lens design and anti-shake techniques. We've come a long way in actual practical resolution from the 2MP/4MP cameras you mentioned.
  - acqq 16y ago
    > for the same sensor size MP count is better That's very wrong. The number of photons is limited, the effective light-sensitive area drops with more MP, and with small sensors with more MP you then get more noise than a signal. It's hidden by post-processing but that also drops the real information. So less MP is better in a lot of common circumstances.
bogdan_moldovan 16y ago
Olympus has a great page for consumers to understand pixel-print size relationship: http://www.olympus.co.uk/consumer/208_741.htm http://www.olympus.co.uk/consumer/208_741.htm For example, my D300s (12M) at 4288x2848 pixels can be printed at 300dpi (professional photo prints) at a maximum size of 14.3x9.5(inch) = 36.32x24.13(cm) = a little bit smaller than an A3. The same picture can be printed @150 dpi on an A1 (84.10 cm x 59.40 cm) leaving a little bit of border.
yatsyk 16y ago
What annoys me a lot is increase in megapixels in camera phones and stagnation in tesktop\notebook screen resolution. I don't need multimegapixel camera in phone. To share photo with friends on facebook or twitter 0.3MP is more then enough but processing of multimegapixel image is not easy task for small ARM processor, so you get very slow response at all phone photo capturing and processing applications and getting annoying delays. According to desktop screen resolution you are lucky if you can get screen with more then 2MP resolution. And this situation is same for years. It even getting worse after switching to wide screen because now you are getting less pixels on same diagonal and resolution.
- Yaggo 16y ago
  You cannot directly compare digital camera megapixels with display megapixels. The former uses Bayer-interpolation (except very few cameras with Foveon sensor) while the latter has true RGB pixels. In the other words, the digital camera's pixel count of two million is shared between R, G, G, B pixels (500k of each – yes, most sensors have double green pixels). A Full HD monitor has 3 * 1920 * 1080 (sub)pixels. Because of Bayer interpolation, the true resolution of 3MP sensor roughly equals 2MP screen resolution. (Yes; I fully agree with your point that a phone doesn't need megazillion pixels. Sensor size is more important factor when speaking of image quality. [Not to mention the optics.])
  - yatsyk 16y ago
    I'm not comparing them directly I'm comparing increase in resolution for camera phones and monitors. Resolution for mainstream camera phone changed from 0.3MP to 5 MP (same Bayer-interpolated megapixels, technology is the same) but I still need to use same 2MP (true megapixels) monitor for years.

47 points by henning 16y ago

While he's got the ratios right, he's got a tolerance for bad printing that I don't share. VGA for 4 x 6? Maybe if you thought your 110 Instamatic made good enlargements (in those days, 4 x 6 was a premium print). That's newspaper resolution. Double up the dimensions (1.2 MP) and 4 x 6 is just acceptable to my eyes (and it didn't used to be when printer dithering algos weren't what they are today).

michaelhalligan 16y ago
Agreed, with a 12 megapixel camera I never felt printing anything over 16 x 20 was acceptable, even with my 22 megapixel 5dmk2 I don't go much larger than 20 x 30.
- jonah 16y ago
  It all depends on how closely you're viewing them. We have a bunch of photos shot with a 5D (12MP) printed about four feet tall. They look great from a normal viewing distance. Of course, when you put your face six inches away, you can start to see some digital artifacts (stair stepping, etc.) but that's not a problem. The maximum necessary resolution is related to the intended viewing distance. "The standard definition of normal visual acuity (20/20 vision) is the ability to resolve a spatial pattern separated by a visual angle of one minute of arc." From that the maximum resolvable dot size can be calculated for a given viewing distance. http://www.ndt-ed.org/EducationResources/CommunityCollege/PenetrantTest/Introduction/visualacuity.htm http://www.ndt-ed.org/EducationResources/CommunityCollege/Pe... http://www.clarkvision.com/imagedetail/eye-resolution.html http://www.clarkvision.com/imagedetail/eye-resolution.html (Sidenote: billboards usually printed at around 20-30ppi)
  - stan_rogers 16y ago
    20/20 is actually pretty bad eyesight. It's "normal vision", not perfect vision, and when my eyes are "corrected" to 20/20, they're about a quarter-diopter shy of maximal acuity. There is a huge difference to my eyes between pictures printed at a 200-line screen and one printed at a 150-line screen (all other things, like stock and varnish being equal) at a distance of more than one metre (from head-height on a couch to the magazine at the far end of a coffee table). If I were printing from a 12MP original at about four feet tall, I'd certainly run the source through something like Genuine Fractals Print Pro (even a good giclee pattern can't make up for squared-off curves). At four feet in the long dimension (giving a realistic viewing distance of about six feet) I'd notice raggedness at a glance at less than about 80ppi -- but then the dye clouds from a 4x5 negative printed at that size would drive me batty as well.
- gaius 16y ago
  When you go to the cinema, you're looking at an image only 2000 pixels across.
  - deleted 16y ago
    [deleted]

cletus 16y ago

The article referenced this: http://www.nytimes.com/2007/02/08/technology/08pogue.html?_r=2&oref=slogin http://www.nytimes.com/2007/02/08/technology/08pogue.html?_r... The one company that seems to have a clue about this is actually Apple. The iPhone 4 has a 5mp camera in it. Some pundits say things like "I wish it had 8 megapixels or more". In doing so, they show their complete ignorance. Most people couldn't tell the difference between 5 and 8 megapixels. What 8 megapixels buys you is larger files, more noise and slower processing (on a sensor this small). The size of the pixels matter. It's one reason DSLR images tend to be so much better: they have hugely bigger pixels. I'd love to see more good 5-8mp point and shoot cams rather than these ridiculous 14+ mp noise factories.

megablast 16y ago
Well, to be fair, Apple have a different market to Canon/Casio/Sony point and shoot cameras. People aren't buying the iPhone 4 just for the camera. Apple still do deserve props for going for a better camera + lens, rather than the samsung route of more rez.
- GFischer 16y ago
  Nokia, on the other hand, does sell a product specifically as a camera replacement: http://europe.nokia.com/find-products/devices/nokia-n86-8mp http://europe.nokia.com/find-products/devices/nokia-n86-8mp I bought the N86 because I realized I never have my camera when I want it, and I always have my cellphone (GPS was nice, but the killer app for me was the 8mp camera).
ugh 16y ago
Canon, Nikon and Panasonic reduced the number of pixels or kept them the same in their high end small sensor compacts. (Canon G11: 10 MP down from 14.7 MP in the predecessor; Canon S90 and S95: 10 MP; Nikon P7000: 10 MP down from 13.5 in the predecessor; Panasonic LX5: the same 10 MP as the 2006 model and a slightly bigger sensor.) The newest iPhone has a tiny 1/3.2" sensor, those high end compacts usually have 1/1.7" sensors, that’s quite a bit more than double the area. Their pixels are consequently a bit bigger. If Apple made the right decision Canon, Nikon and Panasonic must have, too. They get it and they know that at least their best informed customers (those who actually buy high end small sensor compacts) will also get it. They are probably only (unnecessarily) afraid of the general public, all those who buy the cheapo point and shoots. If you are willing to pay you get appropriate pixel densities.

celoyd 16y ago

The article’s heart is in the right place, but it overstates the case. For example, “Sharpness has very little to do with image quality, and resolution has little to do with sharpness” goes too far if you have a pretty good lens and you’re pretty good at avoiding camera shake. Pixel count is not nearly as important as marketing makes it out to be, but it is important.

seanlinmt 16y ago

If I'm not mistaken, the Mars Rover had a 1 megapixel camera. :)

lutorm 16y ago
Voyager had a .64Mp camera (800px^2)...
jonah 16y ago
Not only that, but it's a monochrome sensor with a filter wheel. It takes the same shot with multiple filters and the resulting images are merged back on earth. My friend worked on that project. [Edit] It has 12μm x 12μm pixels whereas the 5D has 8μm and the 5DmkII has 6μm pixels. However each pixel on the Canons contain three (RGB) photosites to the rover's one. http://www.mwoa.org/Ch31.pdf http://www.mwoa.org/Ch31.pdf
- Tamerlin 16y ago
  No, the Canon sensors also have only one photosite per pixel -- they're still using a Bayer filter on a monochromatic sensor.
  - jonah 16y ago
    Ok, here we're getting into confusion about terminology here. To clarify: In the Bayer filtered Canon CCD each individual photosensor is covered in a colored filter [1] in a pattern such as: B G G R So when capturing an image 1/4 of the sensors are capturing blue light, 1/4 capturing red, and 2/4 capturing green. In contrast the CCD in the rover's cameras do not have filters in front of individual photosensors. Instead, there is a set of filters on a disc which are mechanically positioned in front of the sensor. Using this method three images are taken. On each with a red, green, and blue filter covering 4/4 of those same sensor elements giving you 2x-4x the number of elements capturing each color and thus much higher image quality at a given resolution. B B B B then G G G G then R R R R Similar multi-shot technology was used in the early days of terrestrial digital photography to provide better color, exposure latitude and resolution. [2] for a bit of discussion on multishot vs. single shot medium format digital camera backs. [1] http://en.wikipedia.org/wiki/Bayer_filter http://en.wikipedia.org/wiki/Bayer_filter [2] http://www.luminous-landscape.com/reviews/cameras/h3d50ii.shtml http://www.luminous-landscape.com/reviews/cameras/h3d50ii.sh...

lutorm 16y ago

Not to mention that most of those tiny cameras with huge pixel counts don't have optics good enough to resolve those pixels, so they really are pointless.

aaronsw 16y ago

Are Ken Rockwell and Lew Rockwell related? They seem to share a web designer.

gaius 16y ago

I used to work for... A press agency you've all heard of. We had lots of big prints up about the place. Now, some of these were shot on films like Fuji NPZ (ISO 800 colour negative) or first-generation photojournalist DSLRs (e.g. Nikon D1H, 2.1MP). At 60x40", they looked great. Nikon knew this; their second generation was "only" 4MP (D2H). What matters in resolution is lp/mm; that is how many distinct pairs of black and white lines can fit within 1mm. See here: http://www.bobatkins.com/photography/digital/size_matters.html http://www.bobatkins.com/photography/digital/size_matters.ht... The long and the short of it is, unless you are shooting on a tripod with a cable release and a prime lens, there's really not much point worrying about megapixels. I once had a huge row with people on a mailing list about this; try as I might I couldn't make them understand the simple idea that it doesn't matter how many pixels you have if they can't all be assigned distinct values, there's no additional resolution there. They were the kind of people that bought the most expensive DSLR and stuck the cheapest lens on it. Then again if you'd spent 5 grand on a camera and someone did the maths for you you might be upset too... ;-) Also note that cinema is only 2000 pixels across.

pedrocr 16y ago
lp/mm is just a unit of measure for resolution and is directly constrained by the number of pixels. You can't resolve 10 lines with less than 20 pixels and in practice you need more. The article you quoted compares the same resolution in different sized sensors to show that smaller sensors need to resolve more lp/mm in sensor area to achieve the same file in the end. It shows that for the same MP count a larger sensor is better. What we are discussing is the opposite, for the same sensor size MP count is better. And as far as resolution is concerned that tends to be the case, even if the lens is the biggest bottleneck. In DSLRs we're getting to a point where resolution is more constrained by camera movement and lens quality than number of pixels but at the same time both those bottlenecks are being addressed with modern lens design and anti-shake techniques. We've come a long way in actual practical resolution from the 2MP/4MP cameras you mentioned.
- acqq 16y ago
  > for the same sensor size MP count is better That's very wrong. The number of photons is limited, the effective light-sensitive area drops with more MP, and with small sensors with more MP you then get more noise than a signal. It's hidden by post-processing but that also drops the real information. So less MP is better in a lot of common circumstances.

bogdan_moldovan 16y ago

Olympus has a great page for consumers to understand pixel-print size relationship: http://www.olympus.co.uk/consumer/208_741.htm http://www.olympus.co.uk/consumer/208_741.htm For example, my D300s (12M) at 4288x2848 pixels can be printed at 300dpi (professional photo prints) at a maximum size of 14.3x9.5(inch) = 36.32x24.13(cm) = a little bit smaller than an A3. The same picture can be printed @150 dpi on an A1 (84.10 cm x 59.40 cm) leaving a little bit of border.

yatsyk 16y ago

What annoys me a lot is increase in megapixels in camera phones and stagnation in tesktop\notebook screen resolution. I don't need multimegapixel camera in phone. To share photo with friends on facebook or twitter 0.3MP is more then enough but processing of multimegapixel image is not easy task for small ARM processor, so you get very slow response at all phone photo capturing and processing applications and getting annoying delays. According to desktop screen resolution you are lucky if you can get screen with more then 2MP resolution. And this situation is same for years. It even getting worse after switching to wide screen because now you are getting less pixels on same diagonal and resolution.

Yaggo 16y ago
You cannot directly compare digital camera megapixels with display megapixels. The former uses Bayer-interpolation (except very few cameras with Foveon sensor) while the latter has true RGB pixels. In the other words, the digital camera's pixel count of two million is shared between R, G, G, B pixels (500k of each – yes, most sensors have double green pixels). A Full HD monitor has 3 * 1920 * 1080 (sub)pixels. Because of Bayer interpolation, the true resolution of 3MP sensor roughly equals 2MP screen resolution. (Yes; I fully agree with your point that a phone doesn't need megazillion pixels. Sensor size is more important factor when speaking of image quality. [Not to mention the optics.])
- yatsyk 16y ago
  I'm not comparing them directly I'm comparing increase in resolution for camera phones and monitors. Resolution for mainstream camera phone changed from 0.3MP to 5 MP (same Bayer-interpolated megapixels, technology is the same) but I still need to use same 2MP (true megapixels) monitor for years.