Adobe 29180155 User Guide - Page 78

ADOBE PHOTOSHOP ELEMENTS 4.0 73 User Guide Understanding file compression Many image file formats compress image data to reduce file size. Lossless compression preserves all image data without removing detail; lossy compression removes image data and loses some detail. The following are commonly used compression techniques: RLE (Run Length Encoding) Lossless compression technique that compresses the transparent portions of each layer in images with multiple layers containing transparency. LZW (Lemple-Zif-Welch) Lossless compression that provides the best results in compressing images that contain large areas of single color. JPEG Lossy compression that provides the best results with photographs. CCITT A family of lossless compression techniques for black-and-white images. ZIP Lossless compression technique that is most effective for images that contain large areas of a single color. To set file saving preferences O Choose Photoshop Elements > Preferences > Saving Files, and set the following options. Image Previews Saves a preview image with the file. Select Never Save to save files without previews, Always Save to save files with specified previews, or Ask When Saving to assign previews on a file-by-file basis. Append File Extension Specifies an option for the three-character file extensions that indicate a file's format: Select Never if you don't want to include the format extension, Always if you always want the three-character extension added, or Ask When Saving if you want the flexibility to choose when the extension is added. The default setting is Always. Ignore Camera Data (EXIF) Profiles Select this option to automatically discard any color profiles used by your digital camera. The color profile you use in Photoshop Elements is saved with the image. Maximize PSD File Compatibility Saves a composite image in a layered Photoshop file so that it can be imported or opened by a wider range of applications: Select Never to skip this step, Always to automatically save the composite, or Ask if you'd like to be prompted each time you save a file. Recent File List Contains: _ Files Specifies how many files are available in the File > Open Recently Edited File submenu. Enter a value from 0 to 30. The default value is 10. See also "To save changes to the current file" on page 67 Processing camera raw image files About camera raw image files A camera raw file contains unprocessed picture data from a camera's image sensor. Think of camera raw files as your photo negative. Many digital cameras can save raw format files. You can open a raw file in Photoshop Elements, process it, and save it-rather than relying on the camera to process the file. Working with camera raw files lets you set the proper white balance, tonal range, contrast, color saturation, and sharpening. You can reprocess the file repeatedly to achieve the results you want. Photoshop Elements doesn't save your changes to the original raw file, but it saves the last setting you used to process it.