Resampling Images

Image Size

Pixel Dimensions Width 300S Height: 2000

pixels pixels c

¡10.027

inches t ]

6.667

inches t 1

J 300

c

pixels/inch ' t ]

□ Scale Styles ¡^Constrain Proportions Q Resample Image:

Bicubic (best for smooth gradients]

Figure 4-6: The Photoshop Image Size dialog

If you enlarge an image for printing, your program will produce (i.e., invent) new pixels.* Although enlargements can produce surprisingly good results, the effect of the invented pixels is still not the same as if you took the photo with a higher pixel resolution. Only enlarge images as much and as often as you have to. Photoshop offers three different ways to scale images:

► Nearest Neighbor: This method is not suitable for photographic applications. We do, however, use it for preserving the pixelated effect in screenshots enlarged for book use.

► Bilinear: This is also unsuitable for photographic use

► Bicubic: This can be used for enlargements with a factor of up to 1.5

► Bicubic Smoother: This is the best choice for significant enlargement.

► Bicubic Sharper: This method is great for reducing images, thanks to its slight built-in sharpening effect.

There are also a number of other specialized commercial and noncommercial scaling tools available. The Photoshop tools we have mentioned are, however, a good starting point for achieving great results without having to spend money on additional software. If you need to enlarge lots of images on a regular basis, it is worth taking a look at some of the specialized tools on the market to see if they better suit your needs.

Our own DOP-Upsizing Photoshop plug-in can be used to make effective moderate enlargements and is available as a free download at [73]. There is also an interesting article on the subject by Jack Flesher at the same website.

We recommend that you set the Image Interpolation setting to Bicubic in the General section of the Photoshop Preferences dialog. This ensures

* These are usually calculated from the average values of neighboring pixels using special algorithms.

* These are usually calculated from the average values of neighboring pixels using special algorithms.

Other tools for enlarging images while minimizing quality loss are pxl SmartScale from onOne Software (www.ononesoftware.com), or the freeware imageN (www.pixoid.com).

that the bicubic method is applied if no other explicit settings are made (figure 4-7).

Figure 4-7: Selecting the default interpolation (scaling) method.
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