Are you tired of resizing an image to various output sizes and applying a different level of sharpening?  Are you tired of folders full of image.psd,  image_11x14.psd, image_16x20.psd, etc?

When it comes to preparing a file for printing there seems to be a new thought process and workflow emerging.  I first learned of it when viewing Luminous Landscapes “From Camera to Print”, (which, by the way, I highly recommend).   It simplifies the printing process considerably by eliminating the need to resize an image most of the time.

The basis for the approach is understanding how much “resolution” you need for various print sizes, based on the appropriate viewing distance for that size of print.  In the video Jeff Schewe talks about this with references to Bruce Fraser’s book “Real World Image Sharpening”.

What it boils down to isn’t complicated, but a little tough to explain.  Basically, a print has an optimum viewing distance based on its size.  Human vision can resolve less and less detail as it gets further from an object.  This means the necessary DPI to produce a print only needs to meet or exceed the ability of the eye to resolve detail at that prints optimum viewing distance.

Got it?  It’s a little confusing ... I rewrote that last paragraph 5 times trying to “boil it down”!  Lets walk through an example.  To start with you need to determine the appropriate viewing distance.  This can become subjective, and is definitely not a hard fast rule, but a generally accepted guideline is 1.5 times the diagonal of the print.  This would mean the optimum viewing distance for a 11x14 is about 27”.  According to Bruse Fraser’s book (and he explains very well how he arrives at these numbers), at 24” away, the eye can only resolve 143 PPI, so at 27” you don’t need 360 DPI to produce an acceptable print. 

The process is easy to do, and really speeds up the workflow.  In the print dialog box, use the Scaled Print Size area and set your final image size.  Here I am setting the printer driver to print an 11x14 print from my native file.  As you can see, to accomplish this the driver will scale the print 97.63%, resulting in  a final resolution on the print of 245 PPI - more than enough resolution for an 11x14 of this image.

It’s a little more complicated because prints can and sometimes should be viewed at a distance closer than “optimum”.  I think the important concept is the printer is more than capable of doing the image scaling for you unless you are needing to do some serious uprezzing.

So if you “properly sharpen your file” as Jeff Schewe states, you can send the native file resolution to the printer, as long as the resulting PPI meets or exceeds the amount necessary for that optimum viewing distance.  Printing an 8x10?  At a distance of 19”, the eye can only resolve around 180 PPI.   So as long as your print dialog box shows a DPI larger than that, it should look fine.

Only if the resolution drops below those sizes do you need to uprez the unsharpened image, and then sharpen. 

I’m a little more conservative, knowing that many prints won’t be viewed at the optimum distance and many will be viewed closer.  I also like big prints with lots of detail, so 240dpi is about as low as I go before I consider uprezzing (or consider not even printing it that big).

Remember uprezzing is a compromise.  It is creating data and by nature will not be as sharp as if the original capture contained that data.  I would prefer capturing with a better device, but sometimes you can’t or you didn’t. Many images do not contain a lot of small data, and can uprez very easily.  If you do uprez, according to Jeff, (and I concur with him), you should base the uprez on the file itself and not an intended output.  The basic premise here is to make sure you take advantage of bicubic sharpening, especially Photoshops Bicubic smoother.  To do this you must uprez in an even increment ... 200% or 400% (note that it takes a really good capture to use 400%).  Don’t uprez to 240dpi at your intended print size, instead uprez to 200% even if it is “larger” than you need, then do appropriate sharpening on the new image, and send the results to the printer in it’s new native resolution.  This gives you the best chance of effective sharpening, improving the final image.

I like the concept and have been trying it out.  It works. I hate having to resize an image several times, then sharpen, to get different size prints.  Much nicer to have a nice master file and just print the various sizes - it sure speeds up the workflow. I’m not sure anyone can visually see the difference between a file that was resized to 360dpi, sharpened and printed, than one that was sharpened at native resolution and sent to the printer, letting the printer scale the image to the final size. 

WHAT ABOUT SHARPENING?

In the sharpening workflow as taught by the book, the concept is to resize the image to an optimal DPI for your final printed size, and then perform output sharpening at that resolution. With this workflow, every file is resized to a “native” resolution for the printer, for example 240 or 360dpi for Epsons higher end printers, or  300/600 DPI for Canon ipf printers.

So when it comes to sharpening, the new workflow seems to be contradictory.

Sharpening is still a cross between black magic and voodoo to me - I thought I was pretty good at it until studying Bruce Fraser’s book “Real World Image Sharpening”.  Gradually it is starting to make sense ... I guess you could say I see a light at the end of the tunnel. As I pondered the seeming contradiction, some logic started to creep in, and I have a theory as to why this works.  (Some day I’ll get up the nerve to ask Jeff Schewe if my logic is sound or if I’m out in the night, for now I’ll just go with my gut)

Sharpening is about creating more contrast at edges, darken the dark pixels along an edge, and lighten the light pixels.  Proper output sharpening results in halos and to be honest usually looks pretty bad at 100% on your computer screen.  I have been under sharpening most of my images for years, and only recently have been willing to try printing based on something other than what I see at 100% on the screen.

The size of halos is related to the size of the edge and detail of the image, and if you think about it, the size of the halo will scale proportionally as you change the image resolution.  So if you uprez and then sharpen, you have to use a higher setting to get the same affect.

With this new workflow, you can sharpen optimally based on the actual native resolution, and let the printer handle the scaling.  If you have properly sharpened, as Jeff puts it, the sharpening will hold up because the size of the halo changes in the same proportion as the size of the detail.

I would recommend you try it.  That brings to mind a question ...Why the change?  I don’t have a real answer, perhaps maybe those that really understand what is happening at the raw pixel level are just learning more and enlightening the rest of us.  My guess it has more to do with printers and printer drivers.  It I think printers are much better at dithering the images into dots, and when resizing an image, the new screening technologies in them just do a much better job than they used to.  Kind of like how it used to be better to uprez in multiple steps at 10% increments, but new technology in Photoshop, Bicubic Smoother,  makes that unnecessary.  Technology is just getting better.

That’s my best guess anyway!