How Many Megapixels Are Enough?

[TrapperJohn]

A lot of that comes down to the number of base colors and size of the halftone matrix.

If one assumes a 16x16 matrix (pretty typical for 4 color halftoning) to make up one pel (printable element), then 1200dipi actually becomes around 80ppi. With six color, what most of the high end printers use, the matrix can shrink to around 10x10, up to 120ppi.

Factor in the media used to print - ink reflects color far better than fused toner, which is why color lasers tend to be a bit lame - toner can't be controlled as precisely, and it doesn't reflect light as precisely as ink. Plus the color of the base media that the ink is deposited on.

If you move to a continuous tone printing method, like dye sublimation, then there is no matrix. Color is achieved by blending dyes on a single dot, rather than blending individual dots of a fixed color. Typical dye sub is around 250ppi, but then one has to factor in how to blend the dyes to get the correct color, very much like a color film print. Howeve,r dye sub tends to be very expensive as it wastes a lot of media, and as of today, only one factory actually produces dye sub media. Xerox recently brought out a wax color printing method that uses blocks of color wax, a more efficient approach.

Looming over all of this is the rise of the electronic display, which emits light rather than reflecting ambient light as all prints do. It's why slides always looked better than prints. Resolution can be laughably low, because color control is so much more precise when the device can originate the light, rather than reflect ambient light. Today, photographs are typically displayed on an electronic device: usually web display, and lately large high def televisions, and the increasingly inexpensive electronic photo frames. The future is definitely headed away from traditional reflective display of photos.

It's ironic that, as technology allows for much greater pixel density on the sensor, display technology is obsoleting the need for those extra pixels, by making emissive displays more affordable.

 

[KLO82]

It seems to me that 160-165 PPI is adequate for sharp inkjet photo prints from Bayer sensor cameras at base ISO (prints that will be seen from close distance). More PPI is needed from the same camera at higher ISOs. For an 9x13.5 inch print, it results in 2160 x 1440 pixels = 3.1 Mega Pixels. For cropping, the higher the pixel count, the better. This is specially true for bird photography (in addition with sharp tele lens). And creative cropping can result in fantastic images.

 

[dmartin92]

It is very gracious of you to thank everyone individually for their advice and comment, but if you do not "Quote" something of what they wrote in your response, (as in my example, above)....... we don't know for sure WHO it is you're thanking in each case.

That's a very astute comment, Barrie. Thanks for pointing that out.

 

[Chaney1970]

I'd rather have less noise at higher ISO

Wouldn't we all? Unfortunately, noise is not a function of resolution. If it were, why do 6MP rebels look like crap compared to 18MP rebels? QED.

The answer, though: Because noise performance is based on the design of the sensor, not its resolution. There's more engineering and R&D in the sensor that came out last year rather than the one that came out eight years ago. There are APS-C sensors that are starting to look a lot like FF ones.

The old myths regarding sensor size and resolution are falling apart in the face of the changing landscape of sensor design. Parroting these myths merely makes you look ignorant. Quit it.

and will surely enjoy the relative smaller size of the Raw files. Snappier to process

I understand that this can be a problem. If you can't afford to buy a faster computer, then reducing the file size is really your only other option.

The fact that not every camera gives you the option of shooting in a smaller RAW size (especially one that you specify) is a little strange.

However, wishing that the resolution of a camera was, by default, smaller merely because you are cheap is a strange wish. Surely you understand that not everyone is in your same predicament.

and easier on storage and back-up demands.

Storage is cheap. My 2TB drive was $100; it's even cheaper now. That's somewhere around 67,000 15MP RAW files, literally less than a cent ($0.001) per photo. You're shooting 10MP, so that's even more savings.

For Compact cameras with small sensors 3 to 5 MP does it.

Well, they don't make those. Period.

I can see certain situations where having 12+ mega pixels will be an advantage. Lets say you are an eminent photographer who has his work blown up to poster size, or even several feet across to fill the walls of exclusive art galleries.

If that's what you do, you need the Nikon D3x or Canon 5D Mk II or whatever. Maybe even a digital Hassleblad or medium/large format film.

But just I don't think DSLR ordinary users need more than 6 - 12 Megapixels. It's all marketing spin that does not help the amateur photographer/enthusiast. And those mps clog up memory cards and computer memory and imaging software performance for no gain in most cases.

I think the only reason high megapixel sensors like the 18 mp rebels vs the 6 mp rebels look better is due to improvements in sensor technology. Therefore, a 6 mp rebel made with the same technological advantages as the newer rebels would look much better than the current 18 mp rebels.

So pixel density is a big factor, but not the only factor. It can be offset by improved sensor design...but would be better again with a combination of both lower pixel count AND newer sensor technology.

When it comes to point and shoot compacts, high end cameras like the Canon S90/5, G12, Panasonic LX5, Nikon P7000 stuck at, or even have gone back down to lower pixel counts (e.g the G10 was 15 mp and the G11 went down to 10 mp) to give better image quality.

That seems like proof to me that pixel density is definitely a big factor.

I think 6mp is enough for a compact. My Fujifilm F31fd had maybe optimal pixel density for a compact. I can't imagine wanting to blow up images from a compact to any larger than A3.

I just don't see the point of having an 18 mp compact when 99.9% of the images I shoot need only 3 - 6 mps. It's like carrying around an elephant gun when hunting rabbits, just on the off chance you may stumble across a pachyderm.

 

[efrench]

.08 gigapixel camera is in production. .1 gigapixel chip has been produced by Canon. .215 gigapixel chip has been announced by RED for their 6X17 camera.

Why do you think sensor technolgy will stop before reaching gigapixel sizes?
--
http://www.efrench.members.winisp.net/

 

[z00ts00t77]

Dynamic range is the number of stops from the "lowest meaningful signal" to the "full well capacity" as in how many electrons can go into a photosite.

Umm, When the guy asked 'What is DR?', I really don't think that answer would would have helped him much. Waaaayyy too much jargon...

 

[WGArts2]

More pixels increase DR . More pixels = less read noise.

Absolute rubbish.

 

[WGArts2]

I'd rather have less noise at higher ISO and will surely enjoy the relative smaller size of the Raw files. Snappier to process and easier on storage and back-up demands.

Also Video would exhibit less moire artifacts and performs MUCH better in low light.

For Compact cameras with small sensors 3 to 5 MP does it.

10 MP is a good answer. A simple calculation wih a few basic assumptions will yield the result that 10MP is about the right number of pixels to equate to the resolution of Kodachrome 25 in a 35mm camera.

 

[nugat]

It won't stop, but cooling issues, especially in the video mode, will relegate those to specialist uses. Gigahertz microprocessor race ended similarily.

 

[SteveHageman]

http://en.wikipedia.org/wiki/Answer_to_the_Ultimate_Question_of_Life,_the_Universe,_and_Everything#Answer_to_the_Ultimate_Question_of_Life.2C_the_Universe_and_Everything_.2842.29

42 is THE ultimate answer to everything.... Natch....

--
Glad to have digital cameras....

 

[TechOutsider]

I doubt that he was seriously interested judging by the dozen or so 10 character messages he posted in the span of 5 minutes. But I gave him my best answer .

Dynamic range is the number of stops from the "lowest meaningful signal" to the "full well capacity" as in how many electrons can go into a photosite.

Umm, When the guy asked 'What is DR?', I really don't think that answer would would have helped him much. Waaaayyy too much jargon...

Really? How does a D7000 with 16.2 MP have more DR than say a D40 with 6 MP?

More pixels increase DR . More pixels = less read noise.

Absolute rubbish.

--
http://www.flickr.com/photos/techoutsider

 

[TechOutsider]

I'd say the part about slowing down processing to be true if not universally true as computer hardware improves.

But just I don't think DSLR ordinary users need more than 6 - 12 Megapixels. It's all marketing spin that does not help the amateur photographer/enthusiast. And those mps clog up memory cards and computer memory and imaging software performance for no gain in most cases.

True, sensor technology advances allowing.

One thing to also consider is that an 18 MP Rebel doesn't need as heavy as a CFA (color filter array) as a 6 MP Rebel. The lighter CFA allows for greater light transmission and sharper images. So a 6 MP Rebel would be disadvantaged by this fact.

Also, the 18 MP rebel resolves much more detail than a 6 MP Rebel simply because of its sensor which has finer pixels.

I think the only reason high megapixel sensors like the 18 mp rebels vs the 6 mp rebels look better is due to improvements in sensor technology. Therefore, a 6 mp rebel made with the same technological advantages as the newer rebels would look much better than the current 18 mp rebels.

There is no evidence supporting the statement that a constant amount of pixels + continuously improving technology will beat continuously rising pixel count and improving technology.

In fact, the extra pixels provide benefits such as lighter CFAs as previously mentioned, smoother tonal graduations (part of a "good" dynamic range), and detail to sacrifice when noise becomes an issue. If you don't believe me, read up on "John Sheehy" and his recent thread titled "Bad Little Pixels."

http://forums.dpreview.com/forums/readflat.asp?forum=1018&message=37472402&changemode=1

So pixel density is a big factor, but not the only factor. It can be offset by improved sensor design...but would be better again with a combination of both lower pixel count AND newer sensor technology.

Valid observation. I'll expound on the last part on "better image quality."

Read this too:

http://www.dxomark.com/index.php/en/Our-publications/DxOMark-reviews/DxOMark-review-for-advanced-compacts

When it comes to point and shoot compacts, high end cameras like the Canon S90/5, G12, Panasonic LX5, Nikon P7000 stuck at, or even have gone back down to lower pixel counts (e.g the G10 was 15 mp and the G11 went down to 10 mp) to give better image quality.

The manufactures stuck with 10 MP because with more pixels, you resolve a proportionate amount of detail and noise in good light.

In poorer lighting, 10 MP provides for a reasonable amount of detail and keeps the amount of visible noise down in the image simply because the 10 MP sensor doesn't resolve as much as a higher megapixel sensor.

They could even have put 16 MP in say the LX5, but they chose not to because in poor lighting noise would be an issue when viewing the image at a 1:1 ratio. People choose to view the images at 1:1 which creates a scaling error. Comparing a 10 MP image at 1:1 and a 16 MP image at 1:1 gives a leg up to the 10 MP image. It's like comparing a wallet print to a 3 by 5 print .

This can be overcome though by effective noise reduction and downsizing and may possibly result in even better results than the other 10 MP cameras are capable of because noise reduction works better than bigger pixels.

That seems like proof to me that pixel density is definitely a big factor.

The "optimal" number is ever-increasing.

I think 6mp is enough for a compact. My Fujifilm F31fd had maybe optimal pixel density for a compact. I can't imagine wanting to blow up images from a compact to any larger than A3.

Again, having more pixels provides for greater flexibility when it comes to image quality. While you may not ever use the full 18 megapixels, they can be put to good use in making ... say ... a quality 10 MP final image.

On a technical note, I don't think we'll see a 18 MP compact camera - only DSLRs with a 3:2 aspect ratio have 18 MP sensors while 4/3rds cameras and 4:3 compact camera sensors stick with 16 megapixels .

I just don't see the point of having an 18 mp compact when 99.9% of the images I shoot need only 3 - 6 mps. It's like carrying around an elephant gun when hunting rabbits, just on the off chance you may stumble across a pachyderm.

--
http://www.flickr.com/photos/techoutsider

 

[Roger99]

--

It is the mark of an educated mind to be able to entertain an idea without necessarily accepting it. -Aristotle

The one serious conviction one should hold is that nothing should be taken too seriously.
...oh, and I see by the lack of responses that I am right yet again.

 

[TechOutsider]

I've only seen improvements since the D40x days in DSLRs. What happened?

Your theory is the equivalent of the geocentric/Ptolemic model of the universe. In other words, wrong . To explain all the clear gains in IQ, you need epicycles In other words - a complex set of explanations and exceptions.

10 MP is a good answer. A simple calculation wih a few basic assumptions will yield the result that 10MP is about the right number of pixels to equate to the resolution of Kodachrome 25 in a 35mm camera.

That would be changing (specifically increasing) every 12-18 months .

As many as you can get with acceptable noise levels (nt)

--
http://www.flickr.com/photos/techoutsider

 

[GDEllis]

Why on earth would you think someone was just spamming?

Thanks for the article, by the way. I look forward to reading it.

Gary

 

[GDEllis]

Good point!!

Gary

Thanks very much.

Gary,

It is very gracious of you to thank everyone individually for their advice and comment, but if you do not "Quote" something of what they wrote in your response, (as in my example, above)....... we don't know for sure WHO it is you're thanking in each case.

Just thought I'd mention it...
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"

 

[z00ts00t77]

On a technical note, I don't think we'll see a 18 MP compact camera - only DSLRs with a 3:2 aspect ratio have 18 MP sensors while 4/3rds cameras and 4:3 compact camera sensors stick with 16 megapixels .

I just don't see the point of having an 18 mp compact when 99.9% of the images I shoot need only 3 - 6 mps. It's like carrying around an elephant gun when hunting rabbits, just on the off chance you may stumble across a pachyderm.

I think we'd all agree that you really don't need 18mp in a compact camera. However I think many novice camera buyers think that say a 12mp camera is inherently better than a 10mp camera. And manufacturers and big retailers aware of this logic, and quote MP size in advertisments, hoping to trump others. Well done to Canon for pegging back the MP on the G and S series, but these are cameras for enthusiasts. I think the worst offenders for over the top MP are the so called 'Style Cameras'.

 

[Chaney1970]

The manufactures stuck with 10 MP because with more pixels, you resolve a proportionate amount of detail and noise in good light.

In poorer lighting, 10 MP provides for a reasonable amount of detail and keeps the amount of visible noise down in the image simply because the 10 MP sensor doesn't resolve as much as a higher megapixel sensor.

This can be overcome though by effective noise reduction and downsizing and may possibly result in even better results than the other 10 MP cameras are capable of because noise reduction works better than bigger pixels.

You have far more technical knowledge than me, and present 'The other side' of the argument very well. I have already agreed that certain, rare professional users (for example, those who need to blow images up to several feet across) will benefit from the mega pixel race.

I am arguing from the point of view of the vast majority of digital compact/DSLR users (casual snappers through to keen amateurs/enthusiasts) and their practical, real world needs.

For 99.9% of users, a ridiculous strategy singling out mega pixels as a camera's key selling point is making photography less...not more convenient for ordinary users.

Why should I have to keep upgrading my memory cards, computer hardware and software to process ever increasing file sizes, when 6 MP in a compact and 12 MP in a DSLR was all I ever needed?

Keeping down visual noise ("hey, why are my pictures all speckly and weird?) is a key part of getting quality images. Why should I have to downscale images to view them, or go to all the trouble of having to apply noise reduction? The average person will just look and see more noise, and enjoy their photos less. And heavy noise reduction can give an artificially 'shrink wrapped' look to images.

The fact that for their premium compact line, Canon went down from 15 mp with the G10 to 10 mp with the G11 speaks volumes. I hope more manufacturers will follow this sensible philosophy and end the mega pixel race.

Yes, I see the need for the D3x and it's successors. But only a tiny fraction of professionals need that high mp capability.

 

[The Davinator]

Thank you!

Gary

Don't be so quick to thank someone that provides a perfect example of why a little knowledge can be a dangerous thing.

If one were to compare a detailed landscape at 20x30.....one taken with a 12mp DSLR and the other with a 21mp DSLR.....you'll quickly find the 12mp image to be lacking.....at 40" even more so.

For print sizes in the 30 to 40 inch range, for a detailed high quality print, more than 12mp is required.

 

[The Davinator]

Proper viewing distance is the excuse some photographers need to make for using low resolution capture media.

In gallery settings, even with large prints, people normally begin the viewing by standing back....then they get close to the print to immerse themselves in the image. Disappointment follows if the details don't hold during close examination.

Proper viewing distance doesn't exist in the real world....only in the minds of photographers who don't have the right tools for the job.