target="_blank" rel="nofollow" href="#i000038700000.jpg"/> If you start with an image that was originally sampled for a web page and you want to print a large poster, you can forget about using Elements or any other image editor. Upsampling low-resolution images often turns them into the sort of mush shown in Figure 2-4.
FIGURE 2-4: Upsampling low-resolution images often produces severely degraded results.
You might wonder whether upsampling can be used for any purpose. In some cases, yes, you can upsample with some satisfactory results. You can achieve better results with higher resolutions of 300 ppi and more if the resample size isn’t extraordinary. If all else fails, try applying a filter to a grainy, upsampled image to mask the problem. Chapter 11 has the details on filters.
Choosing a Resolution for Print or Onscreen
The importance of resolution in your Elements work is paramount to printing files. Good ol’ 72-ppi images can be forgiving, and you can get many of your large files scrunched down to 72 ppi for websites and slideshows. For a nice-looking print, you need a much higher resolution. Many different printing output devices exist, and their resolution requirements vary.
For your own desktop printer, plan to print a variety of test images at different resolutions and on different papers. You can quickly determine the best file attributes by running tests. When you send files to service centers, ask the technicians what file attributes work best with their equipment.
For a starting point, look over the recommended resolutions for various output devices listed in Table 2-3.
TABLE 2-3 Resolutions and Printing
Go Ahead – Make My Mode!
Regardless of what output you prepare your files for, you need to consider color mode and file format. In the section “Getting Familiar with Color” later in this chapter, we talk about RGB (red, green, and blue) color mode. You’ll likely use the RGB mode most of the time: RGB is what you use to prepare color files for printing on your desktop color printer or to prepare files for photo-service centers. It’s also the mode most commonly used for color images displayed onscreen.
You can also use color modes other than RGB. If you start with an RGB color image, menu options in Elements enable you to convert to a different color mode. Photoshop Elements uses an algorithm (a mathematical formula) to convert pixels from one mode to another. In some cases, the conversion that’s made via a menu command produces good results, and in other cases, a method other than a menu command works better.
In the following sections, we introduce the modes that are available in Elements, discuss when changing an image’s color mode can be useful, and explain how to convert from RGB to the mode of your choice: bitmap, grayscale, or indexed color.
Converting to Bitmap mode
Bitmap mode is most commonly used in printing line art, such as black-and-white logos, illustrations, or black-and-white effects that you create from your RGB images. Also, you can scan your analog signature as a bitmap image and import it into other programs, such as the Microsoft Office applications. If you’re creative, you can combine bitmap images with RGB color to produce interesting effects.
As an example of an effect resulting from combining grayscale and color images, look over Figure 2-5. The original RGB image was converted to a bitmap and then saved as a different file. The bitmap was converted to grayscale and dropped on top of the RGB image. After you adjust the opacity, the result is a grainy effect with desaturated color.
FIGURE 2-5: You can create some interesting effects by combining the same image from a bitmap file and an RGB file.
You can acquire Bitmap mode images directly in Elements when you scan images that are black and white. Illustrated art, logos, or your signature might be the kinds of files you scan directly in Bitmap mode. Additionally, you can convert your images to Bitmap mode.
Converting RGB color to bitmap is a two-step process. You need to first convert to grayscale and then convert from grayscale to bitmap. If you select the Bitmap menu command while in RGB color, Elements prompts you to convert to grayscale first.
To convert from RGB mode to Bitmap mode, do the following:
1. In the Photo Editor workspace, open an image that you want to convert to Bitmap mode in either Expert or Quick mode.
2. Choose Image ⇒ Mode ⇒ Bitmap.
If you start in RGB mode (which is generally the case), Elements prompts you to convert to grayscale.
3. At the prompt click OK.
The Bitmap dialog box opens and provides options for selecting the output resolution and a conversion method.
4. Select a resolution.
By default, the Bitmap dialog box, as shown in Figure 2-6, displays the current resolution. You can edit the Output box and resample the image or accept the default. See the section “The Art of Resampling,” earlier in this chapter, for more on changing image resolutions.
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