Musings on Photography

Pixel density, Prints, and the Future

Posted in digital printing, materials, traditional materials by Paul Butzi on September 8, 2007


My recent experiences with slideshows on the Mac got me thinking. The ongoing discussion about the resolution/Pixel density of the Nikon D3, along with the news about the pixel density of the newly announced Apple iPod – that got me thinking even more.

The pixel density for displays, back in the good old days, was 72 pixels/inch. Oh, if you had a really high resolution display adaptor and a really good CRT display, you could get it higher, but 72ppi was pretty much the norm. Nowadays, LCD displays seem to have a pixel density more like 100 ppi. That’s the density on the MacBook Pro I’m typing this on, for instance.

The pixel density on the recently revamped iPod Nano is, according to Apple, the highest pixel density they’ve ever shipped in a product. It’s apparently a QVGA (320×240) 2″ display, which works out to about 200 pixels per inch. Call it double the resolution of the screen I’m looking at. And the display of the newly announced Nikon D3 is 640×480 (after we sort out all the nonsense stuff about the difference between dots and pixels) in a 3″ display, which works out to 240 ppi.

Naturally, as the pixel density increases, the maximum resolution you can display rises as well. One of the main arguments against viewing photos on a computer display has always been that the resolution of the computer display was hopelessly inadequate. At 72ppi, that’s pretty much true. You look at a 72ppi screen, and the phrase ‘high resolution’ doesn’t exactly spring to mind with the speed of summer lightning. At 100 ppi, things are looking better. At 200 ppi, things are looking good; at 240 ppi, they’re really looking good. At 300 or 360 ppi, we start to encounter arguments that adding resolution won’t help much because at normal viewing distances our unaided eye can no longer see the difference.

I will here wave my hands about and make funny faces and strange noises to distract you, and while you are thus distracted ignore the fact that similar claims of “so good it can’t get better” have been made before, and then disproven (think digital audio). The point is not that some fixed pixel density is sufficient for all needs. The point is that lately, the higher resolution is becoming available, the costs are falling, and the computing power needed to drive displays with much higher resolution is everywhere. There’s a world of difference between fabricating a 3″ diagonal 240 ppi display, and fabricating a 30″ 240 ppi display. But I expect that in the end, I’ll be able to drive to the Apple store and buy a replacement for my 30″ Cinema HD that instead of being 100ppi will be more like 300ppi. Not next week, but within my actuarial lifetime as a productive photographer.

Now, viewing a photograph on a display and viewing a print are not the same. The display emits light, the print reflects it. So the display is (ignoring second order effects) more or less independent of ambient lighting, and to look really good, a print needs to be generously lit. (Here’s the formula for adjusting the lighting to the optimum intensity for displaying prints: hang the print on the wall. Increase the brightness of the lights shining on the print until the print starts to smoke. Back the lights off until the print no longer smokes. Stop.)

And, although the furor over dMax of inks, papers, and printing technology seems to have died down of late, it’s still important. A good printing technology will give you a usable dMax of, say, somewhere between 1.8 logD and 2.4 logD. That corresponds to between 6 and 8 stops between dMax and dMin. But the display I’m looking at right now has a contrast ratio of 1000:1 – 10 stops between the darkest and lightest. 10 stops. Ten stops. I’m not going to claim that a wider range is the holy grail of photo display, but I’m pretty sure that 2 to four stop difference is part of why I look at stuff on my screen and think “Holy Cats, that looks good” and then look at the print and think “Um, not so much.”

Color gamut is another story. There are colors I can print but can’t display on my LCD monitors. There are colors I can display on the monitor but can’t print – interestingly, they seem to be mostly very light colors and very dark ones, and those are often the colors I struggle with when printing. All told I’d say I’d call the color gamut issue a win for the monitor, but the fact is that they are mostly *different* and not better or worse.

And so my question is this: when displays offer similar size and resolution to the prints we make on our printers, and the displays offer better options for color, better dynamic range, and so on, what properties of the print will remain that will mean that photographers continue to make prints? Will prints become a thing of the past, or will the object properties of print (the surface finish, the weight and hand of the paper, no need for a power source) mean that despite their limitations, prints are still what we think of as the natural end point of the photographic process?

6 Responses

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  1. Oren Grad said, on September 9, 2007 at 9:35 am

    Very interesting question. Perhaps there’s more than one answer. For my taste, so far, B&W works best captured on film and printed traditionally, by optical projection or contact print on silver paper, while color works best captured digitally and displayed on a (reasonably well-calibrated) screen.

  2. Bryan Willman said, on September 9, 2007 at 9:36 am

    What “the end point” of the artistic process is will be directed to varying degrees by:

    a. Cost. A 360dpi 30″ screen will cost a lot of money. A comparable paper print will cost very little. The screen can show many prints in serial order, the wall can display many many prints in parallel.

    b. Energy. Prints draw 0 watts once hung on the wall.

    c. Weight and portability.

    d. Pre-declared function – if the goal is to cover the wall with decorating objects, I suspect prints will win out for a very long time, in spite of the Bill Gates monitors everywhere approach.

    e. “affordances” – you can draw on a print, throw darts at it, wad it up into a ball and through it into someone’s car, etc.

    But “e” is more of the trend of paper output being disposable. Each physical bit of paper matters little, even if the images on them matter a lot.

  3. Peter Lindner said, on September 9, 2007 at 11:45 am

    It is quite obvious that for many people displays on the wall will be (or is already) a good solution, even with current display quality. I think it is a great idea. Paper prints will still have its place but fact is if I want to show many pictures to someone I use the computer. The screen is already so portable with PDA’s, phones that the “normal” mode of viewing pictures will be on screens (if its not already)

  4. Gordon McGregor said, on September 11, 2007 at 1:07 pm

    Interesting few comments on ‘energy’ being something of a differentiator. Many of the newer e-ink technologies only require energy when a pixel is being changed.

    Sure, for now, that’s only B&W, but it isn’t particularly visionary to see this technology eventually making permanently visible images that don’t require power, unless you want to change the view.

    So hang it on the wall. Forever (for small values of forever). Without charge. Plug a cable in to change the picture when you get bored.

    Probably where the print will still matter, at least for a longer while, is when the print is bigger than the display.

  5. Eric Jeschke said, on September 13, 2007 at 2:02 am

    I think for many people today, the main end result is the web. If you want to show your work to a lot of people, what more efficient and cost-effective way is there?

    Flickr and other sites are providing for the masses the tools that will relegate prints to niche status.

    Don’t get me wrong, I like prints. I just think that for many people this question is already answered.

  6. Martin Doonan said, on September 18, 2007 at 2:51 am

    I suffered an interesting/frustrating (depends on direction you look at it) side-effect of high density screens last week: viewability of applications. While it improves viewing pictures, suddenly 1-pixel thick lines & small icons disappeared due to small size and reduced contrast. The latter might have been due to the crummy TFT screen.

    If displays start going higher and higher resolution, all the interfaces to software will have to be re-written. There is a point for GUIs where more pixels are self-defeating because you just can’t see the buttons/text etc.

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