T h e   R o a d   L e s s   T r a v e l e d

Jan. 14, 2004


By Al Fasoldt
Copyright © 2004, Al Fasoldt
Copyright © 2004, The Post-Standard

   Apple did the right thing when it built its entire "display engine" -- the way OS X shows all objects on the screen -- on Adobe's excellent PDF graphics format. Everything on the screen is shown in near-perfect scaling, no matter how large or small the items are.
   PDF ("portable document format") files are common. Most of you probably know how clever they are. PDF documents look great on the screen, print perfectly on letter-size paper and can even be enlarged to poster size without the dreaded "jaggies."
   But traditional wisdom tells us OS X can't do the same for photos. The "Quartz" display routines in the OS X operating system do a great job, but they just can't smooth out your digital photos. That's just for PDF files.
   Or is it?
   The more I thought about this the other day, the more I wondered. If the built-in PDF-based Quartz graphics code in OS X can make PDF documents look so impressive, no matter how big or small they are shown and printed, why can't it do the same for digital photos? Why can't it smooth out those pixel-popping lines in all the low-resolution still pictures I took with my digital camcorder along the Amazon River? Why couldn't it fix up some of those quick snapshots I grabbed last Christmas?

   
The image shown here is a composite. The left half was saved as a PDF and reopened in Preview. The right half is the original photo, also opened in Preview. Click on the image to view the original screen capture. The image is quite large.

   So I went to work trying to prove that OS X was a digital photographer's angel. Hours later, after realizing I was wasting my time trying to see any smoothing in digital photos from the way pictures are scaled in OS X, I stopped everything and browsed through my collection of PDF documents in an attempt to see what was different about PDFs.
   I had no luck figuring out PDFs -- I know they're partly mathematical instructions, partly a collection of fonts and partly based on actual images -- but I achieved one of those little victories that show how determination can defeat common sense. After all, common sense told me that I could never get OS X to smooth out digital pictures the way it smoothes all PDF documents, but determination told me to keep trying to find the secret.
   And it paid off. If you are an experienced digital photographer, you might not believe what I am going to tell you. It sounds too crazy to be true.
   I found out how to get Mac OS X to take the jaggies out of digital images. Low-res or high-res, good or bad, new camera or old; it doesn't matter. OS X can smooth out any digital image and make it look like it came from a much better camera. Some images will improve more than others, but all of them should benefit.
   But there's a catch. (There always is.) This incredible smoothing occurs on the screen, but it's not something you can save in your images. It's a bonus in the way OS X displays and prints things. You'll see a change in your images, but only when you view them on the screen or when you print them on your inkjet.
   The secret? Turn your images into PDFs. I don't mean you should make them into PDF documents with text and borders and all that kind of thing. I mean you should turn the pictures into PDF files. Simply open an image in Preview, the OS X image viewer, and then export it (from the File menu) as a PDF.
   This turns your picture into something that is not quite an image in the standard sense. It's a compound document, not an image the way JPEGs or TIFFs are. But unlike normal PDFs, it has no text and nothing else besides an image.
   Adobe's excellent Reader software shows your PDF images without a problem, but it doesn't do any smoothing. Only Preview can do that. To view your new PDF image in all its newly minted smoothness, you must open it in Preview. If you're not sure how much smoothing preview achieves, press Cmd-+ to zoom in on the image until the tiniest details are truly gigantic. Then open the original in Preview and do the same thing. Make each Preview window half the width of the screen and arrange them side by side. You should be able to see the difference easily.
   Or you can can view the comparison image I created for you, shown above. The photo, an extreme close-up of a child's face, is a blend of two images. The left half is a PDF version of the image; the right is the original TIFF. You will see an amazing difference in how smooth and natural the PDF seems. Don't judge the difference by studing the small version shown here; click on it to see a much larger TIFF version, taken directly from the screen of my G4.