Operation Manual

426

USING PHOTOSHOP

Saving and exporting images

Last updated 12/5/2011

The standard bit depth for images is 8 bits per channel. To achieve greater dynamic range with 16- or 32-bit images,

use the following formats:

Formats for 16-bit images (require Save As command)

Photoshop, Large Document Format (PSB), Cineon, DICOM, IFF, JPEG, JPEG 2000, Photoshop PDF, Photoshop

Raw, PNG, Portable Bit Map, and TIFF.

Note: The Save

Note: For Web

Note: & Devices command automatically converts 16-bit images to 8-bit.

Formats for 32-bit images (require Save As command)

Photoshop, Large Document Format (PSB), OpenEXR, Portable Bitmap, Radiance, and TIFF.

More Help topics

“Save large documents” on page 409

About file compression

Many file formats use compression to reduce the file size of bitmap images. Lossless techniques compress the file

without removing image detail or color information; lossy techniques remove detail. The following are commonly used

compression techniques:

RLE (Run Length Encoding) Lossless compression; supported by some common Windows file formats.

LZW (Lemple-Zif-Welch) Lossless compression; supported by TIFF, PDF, GIF, and PostScript language file formats.

Most useful for images with large areas of single color.

JPEG (Joint Photographic Experts Group) Lossy compression; supported by JPEG, TIFF, PDF, and PostScript

language file formats. Recommended for continuous-tone images, such as photographs. JPEG uses lossy compression.

To specify image quality, choose an option from the Quality menu, drag the Quality pop-up slider, or enter a value

between 0 and 12 in the Quality text box. For the best printed results, choose maximum-quality compression. JPEG

files can be printed only on Level 2 (or later) PostScript printers and may not separate into individual plates.

CCITT A family of lossless compression techniques for black-and-white images, supported by the PDF and PostScript

language file formats. (CCITT is an abbreviation for the French spelling of International Telegraph and Telekeyed

Consultive Committee.)

ZIP Lossless compression; supported by PDF and TIFF file formats. Like LZW, ZIP compression is most effective for

images that contain large areas of single color.