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How Many MegaPixels for Large Blow Ups

by Louis39 / April 7, 2009 12:59 PM PDT

In the market now for a digital camera. I was wondering, if I want to blow up pictures to say 16 X 20 would I need a camera with 10 or 12 megapixel resolution? Anyway, would appreciate any opinions how many megapixels would produce a sharp 16 X 20 print. Also any suggestions for an appropriate camera. Thanks.

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Print size and pixels
by hjfok / April 7, 2009 1:27 PM PDT

True Photo quality prints usually needs at least 300 ppi. For a 16x20 size print, you need about 30 MP camera. If you compromise to a 200 ppi 16x20 size print (which is still pleasing to the eye but certainly not a true photo quality print), then you can survive with a 16 MP camera.
For a 12 MP camera, you can have 9x14 true photo quality print or 14x21 200ppi print.

So if you want true photo quality 16x20 size print and does not want any compromise, then you will need a Hasselblad 31 MP camera (H3DII-31)that cost $18000 or the H3DII-39 with 39 MP that costs $22000.

And if you will compromise to 200 ppi 16x20 size print, you can survive with the Canon 5D Mark II less than $3000.

If this is still too much, then you can go for the much cheaper solution. Get a software to enlarge your photo. Try the Alien Skin Software Blow Up 2 plug-in for photoshop, it only costs about $230 and can blow the image up to 3200% without much appreciated quality loss.

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According to the NY Times
by kalel33-20416052469708587370302374692233 / April 7, 2009 2:26 PM PDT
In reply to: Print size and pixels

Almost nobody can tell the difference between a 10MP 16x24 and a 13MP 16x24. Here are the articles and an excerpt. .../08/technology/08pogue.html?_r=1&ref=technology .../15/deconstructing-the-megapixel-myth/

From the article:

"I created three versions of the same photograph, showing a cute baby with spiky hair in a rowboat. One was a 5-megapixel shot, one was 8 megapixels and one was 13.

I asked 291 Digital, a New York graphic imaging company whose clients include ad agencies and fashion companies, to print each one at a posterlike 16 by 24 inches. (They were digital C prints, printed on Durst Lambda at 400 dpi, if that means anything to you.)

We mounted the three prints on a wall in Union Square in Manhattan. Then, cameras rolling, we asked passers-by if they could see any difference.

A small crowd gathered, and several dozen people volunteered to take the test. They were allowed to mash their faces up against the print, step back and squint, whatever they liked.

Only one person correctly identified which were the low-, medium-, and high-resolution prints. Everybody else either guessed wrong or gave up, conceding that there was absolutely no difference. "

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Print quality
by hjfok / April 8, 2009 2:28 AM PDT

There are many factors that goes into print quality. But if you just look at pixel count and MP for specific print size, then we can do some simple math and see whether it makes sense.
It is generally agreed that 300ppi is true photo quality print, 200ppi is still very good and hard to tell a true difference for an average person. However when down to 150ppi, an average person may be able to tell the difference.
As for the NY Time article that you quote 16x24 print in 10MP and 13 MP cannot tell any difference, it is true and you should not be able to tell the difference. Why? For a 16x24 print, the 10MP gives about 162 ppi print quality whereas the 13 MP gives about 175 ppi print quality. Your eyes cannot tell the difference between 162ppi vs 175ppi. That does not mean that you will not be able to tell the difference when it is printed from a 36MP camera in 300ppi.
How about the 5MP, 8MP and 13 MP photos? Well, the 5MP camera will give about 110 ppi, the 8MP camera about 136ppi and the 13MP camera rougly 175ppi. The difference is still small and I will not be surprised if you cannot tell the difference. But again if this is put side by side with a true photo quality print of 300 ppi, a good number of people will be able to tell the difference.
Print quality also depends on your original shot. High ISO shots will have more noise and be more apparent when blown up to larger size. Imperfect focusing may look okay at small prints but show up blurry when blown up. The composition and aesthetic quality of the photo also sometimes allow your brain to forgive or overlook some of the imperfections. Furthermore, the image can be resized in Photoshop or plug-in software, this will enlarge photos with much less loss of quality. There are different algorithm for resizing or enlargement.
My point is that if you want to do a large poster print in the best quality with minimal cost, you should use a software to upsize your image. Upsizing the sensor size and MP is a very costly way to increase your print size.

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Sorry wrote the wrong numbers
by kalel33-20416052469708587370302374692233 / April 8, 2009 10:37 AM PDT
In reply to: Print quality

The photos shown were 5MP, 8MP, and 13MP. Out of several dozen people, only one was able to distinguish which ones were the lower resolution and which one's were the higher resolution. All photos were printed at a professional printing store at 400dpi. I would think someone would be able to get up close and see a difference between 13MP and 5MP, but nobody was able to, except for one.

The links I posted didn't work right, but here's the original article.

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hate not having edit
by kalel33-20416052469708587370302374692233 / April 8, 2009 10:39 AM PDT

So when I hit the link, it asked for a subscription. If you just type in "NY times megapixels" in a search then you can view the article without it asking for a subscription.

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NY Times article
by hjfok / April 8, 2009 5:51 PM PDT

Yes, thank you, I read it. I agree with the article. However, for every study or experiment, you have to look at the purpose and methodology, and the pitfalls. The purpose of the study is to prove to readers that upgrading from 5 or8 MP to 13 MP may not make a lot of difference about the print quality of the photos. In other words, upsizing MP is not the main ingredient to improve your photo quality, and I absolutely agree. However, this study is not designed to find out what MP gives the best print quality at 16x24 size, or even bigger. If you pay close attention, the resolution of these cameras stay at the lower quality print at 16x24 size. Again as pointed out previously, true photo quality is 300 ppi whereas 150 ppi is at the lower print quality. The 5-13 MP cameras all have print quality at or below the 150 ppi resolution level for 16x24 size. For the human eye, it is not easy to distinguish between 300 ppi vs 200 ppi (a 100 ppi difference). So it follows that it is not easy to distinguish print quality between 110 vs 175 ppi (between 5 MP vs 13 MP cameras), but a small number of people may be able to, and this is what the news article found too, not surprisingly.
Another important thing to consider is that the quality of the photo also may affect how easy you notice a difference when you enlarge a photo. My experience is that if I have a good shot with good lighting and tact sharp focus, I can enlarge or crop heavily and still get a good enlargement. But if the photo is taken at high ISO with digital noise or if the focus is slightly off, then the same enlargement will look horrible. Why? If the image is near perfect, our brain usually will fill in some of the blanks, kind of like an automatic interpolation. However, if it has defects, we will be more likely to spot them and notice the difference. In the NY Times study, the photo is taken by a professional, likely a pretty good near perfect photo, so it becomes more difficult for an average person to spot the difference. But if you have a less than perfect photo, your large print will definitely look better in a higher MP camera at 300 ppi resolution than at 150 ppi resolution.
But how practical is getting a camera to give high 300 ppi resolution at large prints? Not at all. And that is what I am trying to demonstrate in my original post (with some sarcasm using outrageously priced cameras as examples). It does not make sense to upsize your camera to get the true photo print resolution, and most people do not need to anyways. Does that mean that high MP cameras are useless? No. It is very useful if you crop a lot or if you routinely do a lot of large prints for a living. For the rest of us, upgrading to a higher MP camera does not make a lot of sense, especially if the upgrade is only a few MP more (from 8 MP to 13 MP), it does not make a difference in print quality. You have to upgrade to 30MP plus to really see a difference, and that was my point.
In terms of image sharpness and quality, your camera sensor's high ISO performance, lens quality, lighting, focus, skill, etc play a much more important role than MP alone. I have made a pretty detailed comment in another thread about image sharpness:;forum-threads

By the way, you keep mentioning 400 dpi print on your threads. I just want to comment that dpi (dots per inch) is the printer's output and has nothing to do with an image's resolution or print size. Pixels per inch (ppi)on the other hand represents the image resolution. For printers, anything 360 dpi is good, higher dpi mostly wastes ink and does not add much to the print quality (not noticeable to human eyes).

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300 ppi is not a requirement for large prints.
by Desperado JC / April 8, 2009 11:32 PM PDT
In reply to: NY Times article

Why? Large prints tend to be viewed at a greater distance than small prints. Thus, if there is a discernible difference with close examination, it will not be noticed. It will be the pixel peepers who will closely examine large prints. Large prints are usually not made for these people.

150 ppi is a recognized lower limit for good quality prints. It is quite respectable to use 150ppi when making larger images. Somewhat better resolution will make the photographer feel better about the print, but it will not usually be noticed. Insisting on 300ppi for a large print is a bit myopic when discussing large prints.

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I said it for print
by kalel33-20416052469708587370302374692233 / April 8, 2009 11:55 PM PDT
In reply to: NY Times article

I understand that 400dpi is for print, and I brought it up to show that at the highest print quality(which some would ask what the output was) that there wasn't any difference. We've had to answer quite a few "why does my camera only take photos in 72dpi" here.

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by ferocious20022002 / April 13, 2009 1:35 AM PDT

This highlights a very important point about how the print is produced. There are huge differences in print quality among the various inkjet, laser, diffusion, and thermal ink printers. The only way to really tell is to print a good test picture in the size you want. Both the inkjet and diffusion printers depend on the ink spreading out and blending together to eliminate individual dots on the print. That process can make many fairly low res images look very good.

If you are on a budget to make your own prints, look up test results on printers in some of the camera magazines and also Consumer Reports. The point is to avoid anything with less than outstanding print results. There is no reason to accept less, given the large number of printers that do an excellent job.

And, as another post pointed out, the quality of the original picture is even more important. Any slight out-of-focus or blur in the picture will show up dramatically in a large print, no matter what the resolution of the camera.

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You are talking big numbers...
by jbalboa / July 10, 2014 11:39 AM PDT
In reply to: Print size and pixels

Are you talking $20000.00 pesos, dollars, euros? Sounds like too much for a 31mp camera unless you're a salesman for such camera.

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Not so much megapixels as resolution
by mjd420nova / April 10, 2009 1:00 PM PDT

If you have ten megapixels or twelve isn't the real determining factor, but what resolution you use when you take that photo. If you only have 360 by 480 selected, it won't make any difference how many megapixels you have, it won't blow up well at all. However, if you select 3648 by 4800 resolution, it would use every one of the pixels and will blow up into next year and still look very sharp.

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4mp is better than you think
by maceyman / April 10, 2009 1:11 PM PDT

For what it's worth I've done well over 40 prints (13"x19") with my Canon G3 (4 mega pixels) printed on my Canon i9900 printer. The pictures always come out fantastic! You could put your nose 12" away and not see any grain, smudge, blur or anything to complain about. Sure maybe you could spot something wrong if you have a giant magnifing glass ... but who looks at pictures with a magnifing glass? I admit I'm looking to upgrade to a higher mega pixel (for cropping purposes only). Quality counts more than pixels.

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Resolution and viewing distance
by hjfok / April 10, 2009 6:31 PM PDT

A few posters bring out some very good points. Viewing distance is another big determinant about how high a resolution you need on a print. It is true that bigger prints when seen afar do not need much resolution to look "good". The extreme example is large Billboards, those are printed in 10 to 20 ppi. For a 16x20 print, if your viewing distance is 3 feet away, you need only about 90 ppi to look good. But if you view it from 2 feet away, then you need about 150 ppi to look good. If you are a bit myopic (as one reader says) and look at it from 1 foot away, then 300 ppi may be needed.
And I agree with many posters that the composition and aesthetics of the photo is more important than the actual resolution, because we can always adjust our viewing distance to perfectly view and enjoy a good piece of art. Every person may have his or her preferred viewing distance, it is very subjective. And again my original intention is just to try to say that upsizing the MP is not the best or the only way to get a better looking large print. Often the cost does not justify the size increase. Yes you may have more room to crop. But you can also upsize the photo with software at much lower cost, if you don't think your image has enough resolution for the large print you want. Photoshop has its own bicubic smooth enlargement and there are also plug-in software as mentioned above.

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Screen vs print
by Siteforlife / April 10, 2009 11:57 PM PDT

I found this discussion very interesting, and wonder how it translates into a 1080p 47in HDTV viewing, rather than prints. Of course then distance from screen counts - does that become the primary consideration? It seems to me that many people do not view prints any more, but I like to do so, and this was causing me hesitation in buying a new SLR. As MP creeps up, does it matter for large prints if I get 10 or 12? Evidently not very much. I have a secondary question about printing. How does the print process and its resolution fit into this? My old Canon SLR is film, and I believe that when I first got it, printing was done by old fashioned negative and paper development (yes, very old). I have always felt that the sharpness (or something I could not quite identify) deteriorated when shops started using computers and scanners, although it happened without my realising. There must have been a general changeover at some point, when did it happen, and is there a difference?

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For TVs and computer screens
by kalel33-20416052469708587370302374692233 / April 11, 2009 1:13 AM PDT
In reply to: Screen vs print

You really only need 3MP for these uses because the highest you can go on a TV is 1080 line of resolution, which is 2048

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However you need to pay attention to your source of image
by hjfok / April 11, 2009 6:33 AM PDT

Yes, you don't need much MP to look good on computer screen or HDTV screen, as pointed out above. However many people made the mistake of recording their photos on DVD and play them on their large screen HDTV at home, and usually look bad. DVD has 720x480 resolution, so your image is about 0.3MP, no wonder it does not look that good. Use the SD lot of the TV, or use your computer to hook up to the TV. If you want to display photos on your external hard drive without a computer, then Western Digital has a media player that can do just that. Apple TV and HD DVR can also output higher resolution images to the HDTV from the internal hard drive.

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Printing films and today's digital photo printing
by hjfok / April 11, 2009 6:12 AM PDT
In reply to: Screen vs print

Yes, the good old days of having your own dark room and smelling those hazadous chemicals are mostly over. I'm not an expert in printing but has done some darkroom exposures years ago for my research publications. You have complete control in the process, but you need to be selective, otherwise you will be literally living in that black hole. Then came the era of 1 hr photolabs, and you can print everything you took but sometimes they come back crapy. Has the wrong color, brightness or even loss of sharpness. The self-contained photograph development equipment at these stores depends heavily on the skill of the operator. Each type of film has its own color profile and using the wrong settings will mess up the color. Since these are done in a large batch, the computer just chooses an average brightness of each image for printing, so that can sometimes screw up a high contrast photo, ending up with bad exposures. An inexperienced operator can even cause permanent harm to your film if they are careless in handling your film, exposing your film to outside light (this can be the case in some drugstores or small stores that do not have a real dark room, or the operator did not close the doors tight on the equipment). This can permanently degrade your photo.
Now fast forward to digital darkroom (meaning you sit in your own desk and printing your image off the computer to the printer). This process is also heavily dependent on the skill of the operator (meaning you or the place you deposit your memory card). First of all, your monitor and printer needs to be calibrated to match the color on the computer screen and the color output of the printer. There are many gadgets for this, including the Spyder3 and Huey, etc. Once calibrated, then you can start editing your photos (do not edit your photos before calibration). Then you have to decide how big the size of the print you are going to make for suitable adjustments of the resolution of the image if necessary, by doing upsampling or downsampling of your image with Photoshop, plug-in softwares, etc. Generally 300-400 dpi setting on the printer is more than adequate for a high quality photo print. If you just deposit your memory card in the drugstore, Target or Costco, then your photo is not going to look as good as you would have done them yourself at home (provided you know what you're doing). Why? because the operator of those places mostly do not know how to optimize your photos or printing. Most of them do not calibrate their machines, just print whatever is uploaded. Also, what you see on your computer monitor screen may not match up to what they see on theirs, so results are less reliable. Sending your photos to more professional photolabs always get better results no matter whether it is film or digital.
By the way, if you are interested in the resolution of scanned 35 mm film, I think it is slightly higher than a 16 MP digital camera, about 5380 x 3620, but you may need to double check on this. I have not had any time to mess around with scanning my old film photos yet.

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10 vs 12 MP
by hjfok / April 11, 2009 6:36 AM PDT
In reply to: Screen vs print

You really will not see a difference. This is usually a marketing pitch of the camera company to try to sell their cameras.

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does it have to be digital?
by aronbergvlad / April 13, 2009 9:11 AM PDT

I know the question is focused on digital, but has anyone suggested film? You can get a more-than-decent 16x20 with a 35mm camera....or you can go large format for far, far less than the need-to-sell-a-kidney price of the Hasselblad. I love my Canon digital, but I still think my Nikon film camera is great.

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Large prints
by hjfok / April 13, 2009 12:17 PM PDT

Yes, film SLRs have pretty good resolution, and when scanned are probably close to a 16MP digital image. Of course large format film cameras are the kings of landscape photography, made for large prints photography.
But I think the message here is you don't need to upgrade the MP of your current digital camera to get a good large print. Getting a sharp photo with good lighting and exposure is more important than how many pixels your camera has. A less than $300 software can upsample the image for quality enlargement if needed. Or if you don't want to spend any money, then stand back a few feet from the large print and it will look just fine.
The crazy examples I use are just to illustrate the cost/benefit ratio usually does not justify upgrading the camera MP for larger prints. For you to really see a difference, you will need a well padded wallet or may need to "sell a kidney or two". The large format camera is also not very practical to travel with, especially with all the new airline charges and restrictions. Well if one is still compulsive to pursue the MP, then Hasselblad can actually be rented for that once-in-a-life-time photo project or get a quality medium/large format film camera.

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