FIGURE 2-5: The Image Size dialog box includes a preview window and an automated Fit To option.
Changing the size of your artwork with the Image Size command
You have a number of ways to change the size of your photos and other art. In Chapter 4, I introduce you to cropping (chopping off part of the artwork to make it fit a certain size or to improve its overall appearance and impact). You can also use Photoshop’s Image Size command to change the image dimensions or printing instructions without altering the composition, which is the visual arrangement of the image or artwork. All the content of the original image is there, just at a different size. Of course, as you can see in Figure 2-6, if you reduce the size of an image too much, some of that original content can become virtually unrecognizable.
FIGURE 2-6: As the smaller image shows at 300% zoom, you can reduce an image too much.
If you know the specific pixel dimensions that you need for the final image — say, for a web page — you can simply type a new number in the Width or Height fields in the Image Size dialog box and click OK. Of course, you probably want a little more control over the process, don’t you? Figure 2-7 gives you a closer look at the resampling options in the Image Size dialog box, with names that suggest when to use each.
If you’re resizing an image that uses layer styles (see Chapter 11), you want to click the gear button in the upper-right corner of the Image Size dialog box and make sure that the Scale Styles check box is selected to preserve the image’s appearance as it shrinks or grows. In a nutshell, layer styles (such as shadows, glows, and bevels) are applied to a layer at a specific size. You can scale the image without changing those sizes, or you can scale the image and change the style sizes proportionally. Not scaling layer styles can dramatically alter the appearance of a resized image, as you can see in Figure 2-8. A slight bevel combined with a small drop shadow produces a subtle 3D effect in the original (upper) image. Below, when the image is scaled down to ¼ the original size without scaling the effects, your chips change to chumps, and the artwork is ruined.
FIGURE 2-7: When either Preserve Details option is selected, you’ll also see a slider just below it in the Image Size dialog box to control noise in the enlargement.
FIGURE 2-8: Scaling an image without scaling its layer styles can ruin your image.
The link to the left of Width and Height should almost always remain selected. Some exceptions might come up, but you normally want to preserve an image’s aspect ratio (the relationship between height and width) when resizing to prevent distorting the image. Figure 2-9 shows you what can happen when you scale one dimension without constraining the image’s proportions.
The Resample option is the one that might require the attention of that gray matter within your skull. Not only do you need to decide whether you want to resample the image (change its pixel dimensions), but you also need to decide how you want to resample. Refer to Figure 2-7 to see that you have eight different ways to calculate the change (called resampling algorithms).
When you deselect the Resample option (as shown in Figure 2-10), you’re changing the print dimensions without changing the pixel dimensions of the image.
When using Image Size without resampling, you’re simply changing the instructions recorded in the image for your printing device. When you enter one dimension, either width or height, Photoshop does the math and fills in both the other dimension and the new resolution.
FIGURE 2-9: Resizing an image without constraining proportions. Interesting, yes, but useful?
FIGURE 2-10: Clear the Resample Image check box to change print size, not pixel dimensions.
FIGURE 2-11: Enter a value, and Photoshop recalculates the fields automatically.
When you resample an image (change the pixel dimensions), Photoshop takes the image and maps it to the new size, attempting to preserve the image’s appearances as much as possible at the new size, using the new number of pixels. Of course, if you take an image that’s more than 3,000 pixels wide and resample it to 300 pixels wide, you’re going to lose some of the detail. And, conversely, resampling an image from 300 pixels wide to 3,000 pixels wide, even when using the Preserve Details resampling algorithm, is likely to introduce some softness to the image’s appearance.
TO RESAMPLE OR TO CROP: THAT IS THE QUESTION
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