47. About Saving Images
1 About the Organizer
48 Save an Image in Photoshop Format (PSD)
49 Save an Image in TIFF Format
50 Compress an Image Using GIF Format
51 Compress an Image Using JPEG Format
52 Save an Image in PNG Format
103 About Color Management
In the world of computing, there is no single, universal definition of an "image file." There are any number of image formats, some of which are used by your digital camera, others within Web pages, and still others when emailing. There's even a special format used by Photoshop Elements, called the Photoshop format. To understand what you're doing when you save and copy images, you have to know more about formats, and why there are so many of them.
The More Common Formats
Digital images can be saved in any number of different formats. The format you choose for your images will depend on the purposes you have in mind for them. For example, if you want to use an image on a Web page, you'll have to save it in a Web-compatible format: GIF, JPEG, or PNG. Each of these formats uses compressionJPEG and PNG in variable amountsto make image files smaller. Compressed images are a benefit to Web users who have lower bandwidth and, thus, longer download times. Compressed images are also great for emailing because they are smaller and easier to send. Here's a brief description of each of the more popular formats:
GIF. One of the oldest compressed formats in wide use, Because a GIF file can contain only 256 colors at most, GIF is great for use with line art such as cartoons and illustrations, and artwork with large areas of similar color, rather than photographic images which typically require more colors to look good. GIF format supports animationbasically multiple copies of almost-the-same image stored in one file. GIFs can also include transparent pixels. When a transparent GIF is placed on a Web page, its rectangular edges disappear, and the image appears to sit right on top of the page as shown here.
If you open an image, make changes, and then save them, certain data might be lost forever when you close that file. For example, if you add a message to an image, it's stored on its own layer. Unless you save the image using the Photoshop or layered TIFF format, when you open the image later on, you'll find that the text has been embedded with the image data. You won't be able to edit, move, resize, or recolor the text, nor will you be able to erase the text and see the image data that used to be below the text.
A transparent GIF blends into the Web page background.
Artifacts Unwanted elements of a digital photo introduced by technology (by the setup of the digital camera, by the scheme used to compress an image file when saving it, or sometimes by the application used to edit the image). In a JPEG image, artifacts typically appear as rectangular blocks of slightly differing color.
JPEG. JPG/JPEG images are perfect for use with photographs or other images with lots of color. JPEG uses a lossy compression technique, in which certain color values in similarly shaded regions are blended with one another in a barely noticeable way, resulting in a smaller color palette and a smaller image file. But if you save a JPEG file over and over again, it will develop artifacts. So, you should save an image in JPEG format only when you are finished editing it. When you want to retouch a JPEG image in the Editor, start by saving it immediately in Photoshop (*PSD) format. That way, you can save all the work you do as you work. When you're satisfied with the touchups, save a copy of the Photoshop image as JPEG. That way, you can avoid creating artifacts as you work on the image. Artifacts might also appear in a JPEG file if it is compressed too much. If that happens to you, simply go back to your Photoshop file and create a new JPEG using a smaller amount of compression. Artifacts might also appear in a JPEG file if the image contains sharp edges, such as a border, a line, or the edges of large text. If that happens, save your Photoshop file in some other format, such as TIFF or PNG.
If you own a digital camera, it probably uses JPEG format. As long as you choose high quality, however, the JPEG compression should be minimal and you'll still get a good quality image. However, if your camera gives you a choice between JPEG, TIFF, or RAW format (all three are commonly used by digital cameras to save image data without loss), choose TIFF or RAW.
JPEG 2000. JPEG 2000 or JP2 format is similar to JPEG, but because it uses a different compression scheme, JPEG 2000 can produce smaller files, retain image quality, and produce minimal artifacts even at high compression. JPEG 2000 handles anti-aliased text better than JPEG, so if you have an image such as a photograph with text, JPEG 2000 might be the format to use. Be sure to see this figure, which compares JPEG and JPEG 2000 files in the Color Gallery.
Alpha transparency Supported by JPEG 2000 and PNG image formats, alpha transparency is simply variable transparency, or the ability to vary the amount of transparency in an image. This enables you to gradually fade the pixels along the edge of an image against a Web page background, for example.
A JPEG 2000 file contains image information in its header about the color space used, which helps to ensure that the file is displayed and printed properly. JPEG 2000 supports lossless and lossy compression, alpha transparency, and 16-bit color. However, if you use lossy compression, then like JPEG format, a JPEG-2000 image can develop artifacts if resaved several times or if overly compressed.
PNG. PNG is a fairly new format on the Web scene, so using it might mean that some users with older Web browsers won't be able to view your Web graphics correctlyand sometimes not at all, especially if the images use transparent backgrounds. PNG does offer a lossless compression method (as does GIF), so it does have that advantage over other Web-compatible formats. PNG files, when compared to GIF files, are typically smaller. They also offer other advantages, such as alpha transparency, gamma correction for cross-platform control, and faster interlacing.
JPEG 2000's major drawback right now is that litigation concerning the originality of its compression scheme has compelled many manufacturers to suspend their support for it. For example, no Web browsers currently support JPEG 2000 (at least, not without third-party plug-ins), so you might not want to use this file type on your Web pages.
This JP2 image is smaller than its JPEG counterpart, yet it retains a higher quality.
Interlacing Also known as interleaving. A method of displaying a Web graphic on a user's screen in which the image is displayed progressivelytypically, the image appears on the Web page quickly but without much detail, and as the download progresses, the image gains detail and sharpness.
TIFF. TIFF/TIF format is great to use when saving photographs or other color-intensive images because as long as you choose LZW or ZIP compression, there is no loss of image data. Unlike JPEG, which uses a lossy compression scheme, TIFF offers two lossless compression schemes (LZW or ZIP). TIFF can also save image layers which makes it a good format for saving your work in progress, if you need to use the unfinished work file on a system that does not have Photoshop Elements or Photoshop. Otherwise, use the PSD format for working images and reserve TIFF for saving copies after you've completed your work.
RAW. A format used by many of the newer digital cameras today. You can think of an image in RAW format as a digital negativeuncompressed, unprocessed raw image data that's been saved in a file. The only problem with the RAW format is that there's no standardeach camera manufacturer has its own particular version of it. Thus, the file extension varies from manufacturer to manufacturer, but look for extensions such as .dcr, .orf, .nef, and .crw. Lucky for you, Photoshop Elements can read the RAW files of the most popular digital cameras, making it the perfect format for taking pictures. However, before you use RAW format on your digital camera, be sure to check Adobe's Web site for its list of compatible camera RAW formats.
Check Adobe's Web site for a list of compatible digital camera RAW formats.
Photoshop. Before retouching a digital photo or creating an original graphic, save your file in Photoshop format (PSD), which is also supported by the graphics editor, Photoshop CS. Saving an image in the program's native format enables you to preserve critical image data such as layers, text, and vector objects. When you're done making changes to an image, you can always save it in a format that's more easily shareable, such as JPEG or TIFF.
If you want to be able to make changes to vector text, vector objects, or elements on layers, you must save the image in Photoshop format or TIFF layered format. When you save an image in any other format, vector data is converted to raster (bitmapped) data, and the image is flattened. This makes individual elements such as text and objects impossible to edit. And because Photoshop format files are typically much smaller than layered TIFF files, PSD is the format of choice for working files.
If you're not going to use your image on a Web page, but simply send it over the Web using email, the image can be saved in just about any format (as long as the recipient has a program capable of reading that format). You might prefer, however, to use a compressed format such as JPEG to make the image smaller and easier to send. If file size isn't an issue, you might prefer TIFF because if you choose a lossless compression scheme such as LZW or ZIP, all your image data is preserved and the result is a high-quality image. If your purpose is to simply print the image, you can use any format compatible with the program you're using to printin this case, any format supported by Photoshop Elements.
Options for Saving Images in the Editor
Saving an image in the Editor is roughly the same as saving a document with any other program: just click the Save button on the Shortcuts bar or choose File, Save and a dialog box appears with the following options:
As a Copy. Select this option to save a copy of the image so that you don't overwrite the existing file. The current image is kept open so that you can continue working, but the image as it looks right now is saved in a new file with copy added to the original filename. Use this option to save copies of your working image at various stages in the editing process. Doing so allows you to go back to an earlier version if some of your edits don't work out.
Include in the Organizer. Select this option to add the image to the Organizer catalog (if it isn't there already). By default, this option is already checked, but you can disable it if you like.
Layers. Select this option when the format you've chosen supports layers (Photoshop PSD or TIFF format), and you want to make certain that the full content and identity of all layers are saved in your file. (This option is disabled if the format you select does not support layers.) Layering is especially important when you're creating an image made up of parts of other images. With the Layers option disabled, the Editor merges all content in the file into a single layer before saving. See 91 About Layers and the Layers Palette for an explanation of layers and how they work.
If you turn off the Layers option when saving a layered image, the As a Copy option is turned on for you. This prevents you from saving a merged version of your image over top of the copy that contains the separate layers. So when you disable the Layers option, your layered, working image is kept open, and a merged, flattened copy is saved to the disk with a different filename.
Save in Version Set with Original. Select this option to group the edited version of an image in the catalog, along with the original version, in a single version set. When this is done, both items share the same thumbnail in the catalog. In addition, when you chose this option, _edited-1 (or another number, if you've edited this image several times) is added to the original filename, creating a separate file so that you do not overwrite your original or other edited copies in the version set. (See 45 About Editing Images.)
ICC Profile. Select this option to include the ICC color profile being used by your system, along with the other image data, in the image file. Knowing the name of this profile will help your printer or other computers render the image as you are seeing it now, rather than making color adjustments you don't want. See 103 About Color Management.
To change your preferences for saving files (such as whether image previews are created), choose Edit, Preferences, Saving Files from the menu.
Not all image formats support the inclusion of thumbnails. For those formats, the Thumbnail option is not available.
To save additional changes to a file you've already saved, click the Save button on the Shortcuts bar or choose File, Save from the menu. To change any of these options for a previously saved image (for example, to save a completed PSD file in TIFF format), choose File, Save As from the menu.
Thumbnail. Select this option to save an image preview. Normally, this option is always on, but if you've changed your file-saving preferences so that image previews are not automatically created when you save, you'll be able to optionally save or not save a preview for particular images. Not saving a preview makes the image file smaller; however, having a preview enables you to view an image's content in the Open dialog box before you actually open the file, for example.
Use Lower Case Extension. Select this option to use lowercase letters in the filename extensionsomething that might be important if you intend to use the image on the Web or on a Linux computer, or if you're burning the image to a CD so it can be read on a computer with a different operating system (such as a Mac). By default, this option is enabled, and it's typically best to leave it like that.