Beginner Printing - Can you have too many megapixels?

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Paul
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#2
In general, no you can't have too many. However some printer/pc combos may not be able to handle massive print files. (by pc I include macs too ;) ).
 
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#3
Or is it better to resize first?
Most pro labs and minilabs can only print to a resolution of 300 - 350 dpi max and then some only from jpg files..for instance my own minilab can only print to 300 dpi but I always have it set up to print from Tiff files or pdf files for anything over 10x8 in size..as jpgs will always throw in some form of compression during the saving process..the human eye can only see approx 300 dpi..unless you are Superman or have x ray vision then you may get a bit more mileage..so I would size for 300 - 350 dpi depending on who's doing your printing any extra they don't need will be ignored..
 
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#4
In theory.. your output sharpening should be print-size specific. If you really want to take control of the process then you should resize first, then sharpen. In that case you'll probably also be wanting to do your own colour management, and therein lies a world of pain.

.. in practice most labs do a decent job of resizing and colour correction ..
 
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#5
In theory.. your output sharpening should be print-size specific. If you really want to take control of the process then you should resize first, then sharpen. In that case you'll probably also be wanting to do your own colour management, and therein lies a world of pain.

.. in practice most labs do a decent job of resizing and colour correction ..
Pain is good!!!!!
 
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Nick
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#6
My main problem with to many pixels is how long it takes to edit them and especially how long it takes to convert them from raw to jpeg. Often my clients want a quick turn around. At a conference last week, after shooting a guest speaker they wanted the photo's on social media ASAP. So I used my 1Dx instead of my 5DMK4 as it's 40% faster to convert those file. Yes I could have shot in Jpeg but the lighting was tricky.
 
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Barry
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#7
The debate is as old aa Digital photography itself. Mainly because there is much confusion over the terms PPI and DPI.... Pixels Per Inch and Dots Per Inch.... they are just not the same and one has a big bearing on the other!

Have a read of this- the difference between PPI and DPI and you may be able to draw your own conclusions.
 
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#8
My DSLR makes pictures with a 24Mpix 'resolution'. That's 6,000 x 4,000 pixels.

My computer monitor (is a bit old) but can only display 1024x768, or 0.76 Mega Pixies... newer ones maybe a few more but the latest generation of high-res monitors only offer up to about 4Mpix on screen.

Any more pixels I may have in the image I get out of the camera, are then going to be significantly 'wasted', by the time I come to look at them, and image re-sized to screen, either just dumping unneeded pixel data, or taking an 'average' of perhaps six image pixels to create a 'display' pixel.

As to printing? Gets more complicated here.

DPI is dots per inch. One dot does NOT equal one pixel. The printer puts down a dot that is normally pure 'black', 'Cyan','Yellow' or 'Magenta', colured ink. Ie the printer may have to may down five or six 'dots' per pixel to make the colour that pixel represents. More, to obtain the shading seen in an image, it will likely work on dot-density principle, laying down maybe a dozen dots of each ink to get the 'shade' over a wider area than the suggested dot-density, that no longer gives you a directly comparable 'resolution'.

Lets say, that the printer uses four ink dots to represent one pixel; that means that at an A4 piece of paper, aprox 8x10 iches, printed at 300DPI, could give you 7.7million dots, but that would only represent just under 2million image pixels... depending on the degree of interpolation to turn pixels into dots, and pack dots to get the same shading, likely a lot less.

So, you would need an incredibly high DPI printer, something that can lay down perhaps 2,400 Dots-Per-inch or more, or start looking at some more elevated technology like multi-layer thermionic printers, that can actually put different coloured dots on properly top of each other, and/or you would have to start trying to print out at very much larger paper sizes, before, like the computer monitor, you started to run out of 'pixels' you captured with the camera, you could show in the picture, on paper you look at.

Oh-Kay.... My first digital camera, over 15 years ago, offered just a 1.3Mega-Pixie sensor resolution. That was more than enough to be able to print 'acceptable quality' A4 prints on a desk-jet printer, and still more than enough to up-load a picture, that probably STILL has to be down-sized to under 1Mpix, for most web and screen -display purposes.

My 24Mpix DSLR gives me enormously more pixes to play with, but ultimately, very very few of them get looked at. In the maths a computer uses to make a display mage from whats taken by the camera, it does give a lot more cope to mess, and does mean that there's a much wider 'pool' of original data for t to 'iterpolate' f I decide to adjust the colour or contrast or anything. Also meas that I ca choose what the computer throws away before it does, taking a 'crop' from my captured image.

That significantly has relevance, when, with as with that little 1.3Mpx digital, it was suggested You don't need a 'zoom' lens, you an 'zoom' digitally..... which did't take two decades of evolution to deny the truth of... B-U-T holds some.... and I chose that 24Mpx DSLR to do just that, anticipating using a fish eye lens that masks 1/3 the sensor to make a round image, to begin with, and cropping a square out of that, wastes 1/3 the pixels left, rendering the out-put o my 24Mpxie sensor, something like, 10Mpix before I start messing more seriously....

To WIT the answer is, that more pixels MAY be 'better'... depends what you want to do. Does NOT automatically mean that having more mega-pixies automatically makes a picture 'better'.

I could take a 24Mpic photo of my foot... its hairy, smelly and probably as hygienic as it is photogenic..... that photo wouldn't be ANY better, because it had 24Mpixies, than if I had taken it with my phone, at its lowest setting to get something 800x600 or less than 0.5 Mega-Pix....

I could take a fantastic picture of my daughter, who is inordinately more photogenic than me, let alone my foot! And a 600x600 low-res phone-cam snap, would still be as worth while as something taken with my 24Mpix DSLR and a prime lens.. especially when down-sized to upload to web, and likely compressed by software by the host-site, to be seen on screen, on a PC or worse still, a smart-phone!

So much of the photo comes from looking THROUGH, not AT the camera, even less the specs for that camera in the manual!

Good photo's are take by good photographers.. and most of it is in the subject to start with..... a better photographer, with a better camera stands a better chance of taking a better photo, BUT, better is utterly subjective, and the hardware is the last thing to have influence on that, and the mega-pixie count only a tiny part even of that.....

So, ultimate conclusion is YES yo can have too many mega-pixies... they tend to take more proceeding power to handle, they ted to take more memory to store or display; not having so many to start with, you can get a camera to work faster, get more pictures on a memory card or hard drive; you can more readily open them and look at them, or edit them.. and unless you are going t get ANY real appreciable benefit from them n what you ultimately look at, they aren't helping you any making them in the first place.....

Otherwise, does it matter? If you can have them and it doesn't hurt any; they cant make the picture worse. BUT they very seldom might make the picture any better. And there's a heck of a lot, so much more worth worrying about.
 
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Jim
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#9
Thanks for the replies/info. I guess to some degree It's subjective depending on your needs.

My point regarding printing is this though; if your looking at an image (say 6000x4000) pixels on a monitor that's a lower resolution you get that weird oversharpened look. Is it possible you can get a similar looking effect (or other weird effect) in a print if the resolution is high enough and the print size small enough? I'm presuming the dots in DPI are much bigger than in PPI? So this wouldn't be an issue for most people most of the time?
 

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#10
.... if your looking at an image (say 6000x4000) pixels on a monitor that's a lower resolution you get that weird oversharpened look.
Eh? Can you explain that weird oversharpened look? In my experience, weird oversharpened looks come from oversharpening, not from your choice of monitor.

What resolution monitor are you using? And what magnification are you using to view the image?
 
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Paul
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#14
For now sending them to be printed.
I'd be surprised if the artefacts show in a print but either way I'd find out what the printers requirements are before anything else. I do my own printing so running a test isn't an issue, may be worth sending one to be printed just to see the results. Who are you planning on using?
 
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#15
I'd be surprised if the artefacts show in a print but either way I'd find out what the printers requirements are before anything else. I do my own printing so running a test isn't an issue, may be worth sending one to be printed just to see the results. Who are you planning on using?
Someone recommended these , they ask for jpgs so I'll be sending 100% quality raw conversions:

http://dscolourlabs.co.uk/
 
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droj
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#19
I think that the jagged patterning you're worried about is just a function of your screen display at that size and that there's no danger of it translating into print.

If you are a total novice, I suggest going through a basic protocol before saving for print. First, and this is an across-the-board one-off, calibrate your display if you haven't already. This can be as rough and ready as you like but begins with screen brightness (try 50%) and contrast, followed by rgb colour balance.

If your screen's too bright it's harder to get prints to correlate and they'll likely come back too dark.

A refinement is to get into 'soft-proofing' using a specific print profile to get a foretaste of how prints on a certain paper might look.

DSCL aren't going to 'improve' your images or compensate for anything, they're just most likely going to print what you send them as you send it, so it's up to you and thus a good test!

Have a couple done (I know, swallow hard and stump up the postage). And not too big. Compare the prints with what's on your screen. There might be conclusions to be drawn as to tone and colour.

Some labs do auto-correct. I prefer it when they don't because I like to be the one in control. It's confusing, but for each lab you need to know how they operate.
 
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#20
If it's in the image then the print will also be affected

This in a nutshell is what I'm failing to understand. It's only visible when viewed smaller than about 50%, but what percentage is a nearish accurate representation of the end product, ie. the print? If viewed at 100% there is no moire.

If I print a 24mp 6x4 inch pic isn't it going to be more visible in that rather than if I printed at A3?
 
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#21
I think that the jagged patterning you're worried about is just a function of your screen display at that size and that there's no danger of it translating into print.

If you are a total novice, I suggest going through a basic protocol before saving for print. First, and this is an across-the-board one-off, calibrate your display if you haven't already. This can be as rough and ready as you like but begins with screen brightness (try 50%) and contrast, followed by rgb colour balance.

If your screen's too bright it's harder to get prints to correlate and they'll likely come back too dark.

A refinement is to get into 'soft-proofing' using a specific print profile to get a foretaste of how prints on a certain paper might look.

DSCL aren't going to 'improve' your images or compensate for anything, they're just most likely going to print what you send them as you send it, so it's up to you and thus a good test!

Have a couple done (I know, swallow hard and stump up the postage). And not too big. Compare the prints with what's on your screen. There might be conclusions to be drawn as to tone and colour.

Some labs do auto-correct. I prefer it when they don't because I like to be the one in control. It's confusing, but for each lab you need to know how they operate.
Yep, you're right. I'll just get some prints done and see what happens. My monitor has been cailbrated in the Windows display tool but that's all. I'll get some prints and go from there.
 
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Paul
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#22
It isn't in the image - if you don't see it @ 100% it isn't there in the image file. It does look like moire, but most likely from the screen rather than the file - so a screen artefact. I have images with moire in, I still see it @100% - in anycase, it is likely to be masked more in a small print than a large one.
 
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Phil
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#25
If I print a 24mp 6x4 inch pic isn't it going to be more visible in that rather than if I printed at A3?
Nope.... chances are you will not see any artefacts, what you are seeing appears to be from your screen rendition.

As others have said it is worth getting a test done by whoever will be printing for you, it does not need to be full sized.
 
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Richard
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#27
It's screen moire, ignore it - see post #22.
 
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#28
Most pro labs and minilabs can only print to a resolution of 300 - 350 dpi max and then some only from jpg files..for instance my own minilab can only print to 300 dpi but I always have it set up to print from Tiff files or pdf files for anything over 10x8 in size..as jpgs will always throw in some form of compression during the saving process..the human eye can only see approx 300 dpi..unless you are Superman or have x ray vision then you may get a bit more mileage..so I would size for 300 - 350 dpi depending on who's doing your printing any extra they don't need will be ignored..
The acuity of the human eye is an angle. The number of DPI/PPI that the eye can discern is distance dependent.

This in a nutshell is what I'm failing to understand. It's only visible when viewed smaller than about 50%, but what percentage is a nearish accurate representation of the end product, ie. the print? If viewed at 100% there is no moire.

If I print a 24mp 6x4 inch pic isn't it going to be more visible in that rather than if I printed at A3?
The issue that you're seeing in your scaled image is called aliasing. It can manifest itself as a moiré pattern, or jagged edges on straight lines, or false sharpness, or ...

The problem is caused by cutting the image up into little samples (pixels). It's a bit hard to explain in terms of graphics, so everyone uses sound. In the image, the black dots are the points in time at which the sound signal is sampled - as you can see, there are two valid signals, you can't know which one it is from the black samples, so the blue signal is the one reproduced by the audio player, irrespective of whether the input was red or blue. The red signal has been "aliased" to the blue signal. To fix it, the audio designer would remove all the input signals that the system can't reproduce using an anti-aliasing filter.



Your camera does the same (although it samples in 2D space, not time) - it removes fine detail from the incoming light using a slightly blurred glass filter in front of the sensor - so detail that is too fine for the camera to accurately reproduce is removed by blurring.

Problem is, say you then down scale the image from 6000x4000 to 3000x2000, but 3000x2000 is no longer enough samples for the amount of fine detail that you've got in the original image - just like in the audio example, you get new, unwanted elements in the image, the aliasing.

How to fix it? Anti-alias (slightly blur) the image before you downscale it.
 
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