# Enlarging digital photos for print



## nickzou (Aug 15, 2011)

So one way my friend suggested that I do is get myself an enlarger, convert my digital pictures to negatives, and enlarge it. First, I don't really have any experience with film or film related paraphernalia but I'm sure I can figure out the enlarger. But is this the only way to go? I'm shooting with a D7000, 16.2 megapixels, maximum resolution is 4928x3264, at 300dpi, that's... 10x16 inches, roughly. I was thinking of making a wallsized print. But... I don't have a D3x or a medium format camera.


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## Big Mike (Aug 15, 2011)

People have been making wall sized prints from digitally captured images for many years now....which means that many of them came from, what we now call, low resolution.  

Firstly, you don't need to us 300 PPI...yes, that is a 'standard' number to go by...but it's unlikely that anyone could tell the difference if you used something like 240 PPI.  

And you also have to consider that for larger prints, you can get away with lower resolution.  100 PPI would probably be acceptable to most people for a poster sized print.  The thing to remember is that large prints aren't meant to be viewed from up close.  A poster sized print, for example, is best viewed from 5 or 6 feet away...and from that distance, it's harder to notice the pixelization that may have come from a lack of resolution.  

Of course, it will be up to you to decide what size vs resolution is acceptable for you...but you won't know until you try.

But going back to your question...there are some very easy ways to increase the resolution of digital files.  In Photoshop, you can simple increase the size and choose to 're-sample', which will increase the resolution.  For going larger, you'll want to choose the 'bi-cubic smoother' option.  You could probably double or even triple the size of the image (if it's a good quality image to start with) and get a decent print.  Again, it's up to you.

Photoshop does a decent job of enlarging digital images, but for many years, the standard has been a program called 'Genuine Fractals'.  It uses very advanced algorithms to enlarge an image while keeping it looking realistic.


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## rlemert (Aug 15, 2011)

If you're concerned about losing resolution, I'm not sure how converting your digital image to film (negative) is going to help. The negative is not going to create resolution that wasn't in the original.


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## nickzou (Aug 15, 2011)

Yeah but I find it looks better than blocky pixels.


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## nickzou (Aug 15, 2011)

Big Mike said:


> People have been making wall sized prints from digitally captured images for many years now....which means that many of them came from, what we now call, low resolution.
> 
> Firstly, you don't need to us 300 PPI...yes, that is a 'standard' number to go by...but it's unlikely that anyone could tell the difference if you used something like 240 PPI.
> 
> ...



Thanks for the info. It was very informative and I have a better idea of how I'm going to approach this print now.


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## ann (Aug 15, 2011)

You have indicated you have no experience with the darkroom process and so I would suggest you take some other advise and use some software to enlarge the file to the size needed to make the print you desire.

Yes film does have a special look, but frankly, there is a learning curve with analog process just as there is with digital and for the time and money needed to produce an outstanding film using a darkroom is going to be costly in terms of learning and materials.

YOu can make a digital negative, but that also means, software , learning curve and then printing it out the size of the print your wishing to make and then finding someone with alternative process experience to make the final print using traditional tools.

There are software programs that will produce a larger file for you, check out Genuine Fractals from Onone or a program i believe called "Blow Up"


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## KmH (Aug 15, 2011)

I disagree that the bi-cubic smoother option is the single choice for re-sampling an image for printing at a larger size, but Mike is spot on about viewing distance and how it affects the PPI an image can be printed at and remain a high quality print.

It all depends on the image. More specifically, it depends on the frequency of the image. A studio portrait is usually a low frequence image. A landscape shot of a deciduous forest is a high frequency image. More info on the particulars is found in Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom (2nd Edition) 

 I often use the bi-cubic sharper algorithm to enlarge an image for printing, and I'm sure not the only one doing so.

A couple of other points:

Digital images are made of square or rectangular pixels, not round dots, so when referring to digital photographs use PPI (pixels-per-inch), not DPI (dots per inch)
Inkjet printers use dots of ink to render the pixels of an image. DPI is a measure of inkjet printer resolution that is separate and not equivelent to digital image resolution, because it usually takes more than 1 dot of ink to render the color of a single digital pixel. Some inkjet printer heads squirt as many as 175 dots of each color. If it is a 6 color inkjet printer, and all 6 colors are used to render the color of a single pixel, it requires 1050 dots to represent the single pixel.
Not all photographic prints are printed on inkjet printers.
Chromogenic prints are made on paper that has 3 layers of light sensitive emulsion, one layer sensitive to Cyan colored light, one sensitive to Magenta, and one sensitive to Yellow. The digital image is projected onto the paper and then chemically developed, most often using RA-4 chemistry.
Note that digital photos are made using the additive RGB color model, while prints are made using the subtractive CMYK color model (both chromogenically and with dots of ink).


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## LarryD (Aug 15, 2011)

When you say "make a wall sized print", do you mean one the size of a wall, or one to mount on the wall  ??

Do you intend to make a lot of these prints all the time, or is this just a large print once in a while..  If the latter, use any professional print service.  Just give them a clean, finished image file and they will do all the algorithms and enlarge the print to any size you want..


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## KmH (Aug 15, 2011)

By the way, a lot of consumer labs don't print chromogenic prints at more than 250 PPI, which is limited by the RIP software their commercial printing equipment uses.


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