Adobe 65089063 User Guide - Page 254

246 CHAPTER 12 Saving Images compress image data without removing detail; lossy techniques compress images by removing detail. The following are commonly used compression techniques: RLE Run Length Encoding is a lossless compression technique supported by Photoshop and some common Windows file formats. In images with multiple layers containing transparency, RLE compression will compress the transparent portions of each layer. LZW Lemple-Zif-Welch is a lossless compression technique that provides the best results in compressing images that contain large areas of single color, such as screenshots or simple paint images. JPEG Joint Photographic Experts Group is a lossy compression technique that provides the best results with continuous-tone images, such as photographs. When you choose JPEG compression, you specify the image quality by choosing an option from the Quality menu, dragging the Quality pop-up slider, or entering a value between 1 and 12 in the Quality text box. For the best printed results, choose maximumquality compression. CCITT CCITT encoding is a family of lossless compression techniques for black-and-white images. CCITT is an abbreviation for the French spelling of International Telegraph and Telekeyed Consultive Committee. ZIP ZIP encoding is a lossless compression technique. Like LZW, ZIP compression is most effective for images that contain large areas of a single color. Saving images You can use the following commands to save images: • Save to save changes you've made to the current file in the current format. • Save As to save an image with a different location, filename, and/or format. The available options vary depending on the format you choose. • Save for Web to save an optimized image for the Web. (See "Saving optimized images" on page 240.) To save changes to the current file: Choose File > Save, or click the Save button ( ) in the shortcuts bar. To save an image with a different name and location: 1 Choose File > Save As. 2 Type a filename, and choose a location for the file. 3 Click Save. To save an image in a different file format: 1 Choose File > Save As, and choose a format from the Format pop-up menu. If you choose a format that does not support all of the data in an image, a warning appears at the bottom of the Save As dialog box. If you see this warning, it is recommended that you save a copy of the file in Photoshop format or Photoshop PDF format in order to support all of the image data. 2 Specify a filename and location.