Field Report
by Gary Gray
As a follow up to my field report on the 300 DPI printing myth, I'm now going to show you a technique for enlarging your digital image files using Photoshop CS3. I've been using this technique since CS3 was released in 2007 and have found that I get better results than I do using Genuine Fractals (The Industry Standard.)
As a general rule, one should avoid adding pixels to their image for prints. Creating image data that doesn't exist can result in less than desirable image quality, however, sometimes you simply don't have enough image size to begin with and when a large print is called for, up-rezing is a necessary evil. Some programs will do it for you when you print by re-rezing the image size on the fly when sent to the printer. The problem I've had with this method is that it is hit-and-miss and wasting a print to find out can cost money. Up-rezing before you print is a better method I believe (for most of us.)
The first question I'm usually asked is "who taught you this technique?"
My answer is "nobody", I figured it out on my own through trial and error. Maybe somebody out there has a better technique. I haven't seen one that gives me better results.
I've read of and tried numerous different techniques in Photoshop the most common advice being dished out is to size up in either 1%, 5% or 10% increments. These techniques will give you varying results and more often than not you'll tend to lose a a little something or introduce pixel halos around the edges of the details. I've also found that Genuine Fractals, does a great job compared to the standard methods available in Photoshop, it too tends to create pixel halos. My trick will give you as much detail and result in virtually no haloing in your images. Don't believe me, try it yourself.
I've created an action in Photoshop and assigned it to one of my function keys. You may wish to try this approach as well, as it will allow you to quickly make enlargements of your file in increments. Essentially, we'll increase the file size in 25% increments and making a sharpening adjustment after each increment. For the purposes of this report, I'm using a full resolution 16 bit Tiff File shot with a Canon EOS 5D. I've found this procedure to be fairly consistent with just about any camera I've used and on original file sizes ranging from 1024 x 768 up to full size images from the Canon EOS 1DsMKII.
I'll begin with an image from my Canon 5D with dimensions of 2916 x 4374 pixels.
Lets start with creating the action.
1. load the image you wish to uprez into Photoshop, then click on the "create new action" icon at the bottom of the actions pallet to begin recording your predefined action. Give your action a a name. I labeled mine 25% Up-Rez, and assigned it to Function Key F3 + Command Key. When I hit Command+F3, the upsizing routine will run, giving me a 25% larger image.
2. Next we resize the image to be 25% larger.
Select Image>Image Size and make your adjustments in the dialogs as follows.
Resizeing the image to 125% of normal, constrained proportions and resample the image. We're using Bilinear resizing here, I've found this method is best for keeping details without introducing halos.
3. Next, we sharpen the image.
Select Filter>Sharpen>Smart Sharpen and make your adjustments in the dialogs as follows.
Check the Advanced button, Set Amount to 90%, Radius to 3.0 pixels, Remove Gaussian Blur and check the More Accurate box. Shouldn't need to touch anything else, but feel free to play around with these settings to explore different results. Click OK.
4. Click the Stop Recording button at the bottom of the Actions Pallet.
You've now created an action that will resize your image up by 25%. Run this action more than once to keep making your image larger in 25% increments. In the case of this image, we've started with a file that is 2916 x 4374 pixels, which when set to 300 dpi for printing (you can go down to 180 dpi and still get good results), you could print the original image at 12 x 18 at 243 dpi and get an excellent quality print. With a 25% uprez, you'll now have the ability to print size of roughly 15 x 22 inches at 240 dpi. Rez up by another 25% and you can now get a print size of roughly 20 x 30 inches at 227 dpi. I try not to resolve an image lower than 180 dpi in practice, but if you've read my earlier essay, you'll know that you can print at 180 dpi all day long without losing print quality. In the case of this image, I've now created a uprezzed image file by using a simple resizing routine that I can safely print up to 24 x 36 at 180 dpi with no significant loss of detail from the original image and in truth will look pretty darn good when viewed from just a few inches away. Once you've resized your image to your liking, feel free to adjust the sharpening and contrast to suit your liking. I normally apply this technique to images before I make serious color or sharpness adjustments. I've never had a problem using this approach.
So, what about Genuine Fractals? Does this technique give as good a result? I think so, and it will save you the cost of another software package.
Here are some cropped samples of the above master image which I've resized using my technique and using Genuine Fractals. Judge for yourself if this technique is worth while.
Both images were resized to 6835 x 4557 pixels. These are 100% crops of portions of each image for comparison. The Genuine Fractals image is the watermarked image on the left, the photoshop resized image using my technique is on the right.
Personally, I think my photoshop upsizing technique renders slightly more detail then Genuine Fractals and whilst this comparison doesn't show it very well, also reduces haloing.
Give it a try, you have nothing to lose.