If you want to do prints whose resolution is larger than that of your digital camera, you could leave the job of digitally enlarging the photos to the printer driver. But in that case you can not be sure of the quality of the prints. Many graphics applications offer an Image Size or Resize feature for enlarging images, but if higher quality is your concern, you should look further. Especially if you want to do relatively large prints, it is essential to use a special tool to produce high quality enlargements.
How do the image sizing features in graphic applications compare?
Photoshop's Bicubic option is OK
for upsizing images up to 200%. The new Bicubic Smooth option
CS is even better for bigger enlargements. Unfortunately
Paint Shop Pro
(up to the current Version 9.0) produces blocky results
when upsizing images, because it offers no real bicubic
method. So better only use its Resize tool for downsizing
on the other hand offers a true Bicubic resize option which
looks better than Photoshop's Bicubic method, but not quite
as smooth as Photoshop CS's new Bicubic Smooth option. Finally,
the popular freeware IrfanView
(Version 3.92) offers a Lanczos resizing option which uses
too few sample points and therefore can produce an unwanted
shadow pattern in some images. So it is better to use the
Bell or Mitchell option which are comparable to Photoshop's
Bicubic Smooth option.
RDK's SmarterResize consists of two automation plugins, which completely rely on Photoshop's Image Size tool. The Web plugin lets you enter the new size in pixel units while the Print plugin lets you enter the print size in inches. As Photoshop's Image Size tool offers the same and even more options, I can't imagine that anyone may want to use this product, even if it only costs $5. Verdict: 0 of 5.
As an automation plugin Fred Miranda's Stair Interpolation Pro also uses Photoshop's Image Size feature. The trick is that it increases the image size in 10% steps and not just in one step. As a result the output has a better local contrast and is smoother than a one-step-enlargement, but if compared to the Lanczos interpolation of some other plugins, it looks as if the details were smoothed a bit too much. Stair Interpolation Pro offers three sharpening and three quality settings, but no preview. Verdict: 2 of 5.
Resize Magic from F-Soft is a filter plugin without preview that needs to be applied two times. At first it stores the image data to an internal buffer, then you have to enlarge the image to the desired size in your graphic application, and finally Resize Magic applies the resized image with a selected sharpness setting. Resize Magic uses Lanczos interpolation which is somewhat better than the standard bicubic method used in Photoshop. Verdict: 2 of 5.
OutdoorGrace ResizeIT comes as an export plugin that lets you save the resized image in various image formats. It offers several interpolation methods, including two proprietary methods, which aren't as good as the offered Lanczos and Cubic Spline Fitting methods. ResizeIT lets you choose the number of source pixels which can help to increase the resizing quality for some images, but also increases the rendering time dramatically. Unfortunately all methods, except the proprietary ones, produce a pixelated frame around the image. Hopefully a future version will have that bug fixed. Verdict: 2 of 5.
X-File from Human Software is a filter plugin that saves the resized image as a TIF file. That means that you have to reopen the saved file, which is a bit inconvenient. In addition to known methods like Lanczos it also offers its proprietary X-File method, which is a touch too smooth, but otherwise good quality. Luckily there is a preview to help you to choose the most suitable interpolation method, but there are no adjustable parameters. Verdict: 2 of 5.
SmartScale (discontinued now)
is delivered as an automation and an import plugin. It offers
a large live preview and four combo boxes with parameters for
adjusting the output quality. If the Edge Contrast parameter is
set to "High", SmartScale tries to redraw the edges which can
make the image look like a drawing. Activating Extreme Edges turns
the image almost completely into a water painting. Using both
settings seems only advisable for enlargements up to 400%. All
in all, SmartScale's results are slightly better than those of
Photoshop CS's Image Size tool. Verdict: 3 of 5.
Power Zoom from DataBecker is a standalone program that is
available in German language and will hopefully become available
in English, too. There are various resizing methods along with
its proprietary Visual Displacement method. It offers several
parameters for adjusting sharpness, contrast and details. Foto
Power Zoom manages to produce enlargements with good contrast
and detail. Because of its extremely low price (approx. $3.50
for the German Version in October 2004) it will be a tough competitor
for SmartScale and PhotoZoom. Verdict: 3 of 5.
(previously known as S-Spline Pro) from Shortcut is available
as a standalone application and as an export plugin that will
save the output as various image files. Among other methods it
offers a proprietary S-Spline option which usually produces the
best results. There is a Unsharp Mask feature and three parameters
for adding grain and increasing edge contrast. However, with increasing
edge contrast the edge colors become unnaturally saturated. So
the interactive preview is a big help for achieving balanced results.
The results are somewhat sharper and more detailed than those
of SmartScale. Verdict: 4 of 5.
Fractals (now called Perfect Resize) comes as a file format
plugin. To enlarge images with it you have to save the image in
its STN format firstly. When opening the STN file again, you can
enlarge it to your desired image size. Genuine Fractals is quite
unique, because it doesn't use standard interpolation methods
like other plugins. With the help of a special fractal algorithm
it produces photo enlargements that are sharper and more detailed
than any of the other mentioned tools. Evenmore, you are still
able sharpen the enlarged images, which isn't possible with other
tools. Still, its output has a fractal-like look which may not
be everyone's taste and for some photos you may wish to get a
more softer enlargement like that of PhotoZoom. Genuine Fractal's
preview works similar like that of X-File, but there are no options
for adjusting the output. Verdict: 4 of 5.
Other newer tools:
Zoom Engine (Verdict: 3 of 5)
Blow Up (Verdict: 4 of 5)
This article was published in Issue 8 of the Digital Photography Techniques Magazine. It was slightly updated for The Plugin Site in October 2004.