Digital Negative format (DNG)

Digital Negative (DNG) is a file format that contains the raw image data from a digital camera and metadata that defines what the data means. DNG, Adobe’s publicly available, archival format for camera raw files, is designed to provide compatibility and decrease the current proliferation of camera raw file formats. The Camera Raw plug‑in can save camera raw image data in the DNG format. For more information about the Digital Negative (DNG) file format, visit www.adobe.com and search on the term “Digital Negative.” You’ll find comprehensive information and a link to a user forum.

References:

• Adobe Help Resource Center: Digital Negative format (DNG)

Photoshop Raw format

The Photoshop Raw format is a flexible file format for transferring images between applications and computer platforms. This format supports CMYK, RGB, and grayscale images with alpha channels, and multichannel and Lab images without alpha channels. Documents saved in the Photoshop Raw format can be of any pixel or file size, but they cannot contain layers.

• Note: A Photoshop Raw image is not in the same file format as a camera raw image file from a digital camera. A camera raw image file is in a camera-specific proprietary format that is essentially a “digital negative,” with no filtering, white balance adjustments, or other in-camera processing.

References:

• Adobe Help Resource Center: Photoshop Raw format

Encapsulated PostScript (EPS)

Encapsulated PostScript (EPS) - language file format can contain both vector and bitmap graphics and is supported by virtually all graphics, illustration, and page-layout programs. EPS format is used to transfer PostScript artwork between applications. When you open an EPS file containing vector graphics, Photoshop rasterizes the image, converting the vector graphics to pixels.

• EPS format supports Lab, CMYK, RGB, Indexed Color, Duotone, Grayscale, and Bitmap color modes, and does not support alpha channels. EPS does support clipping paths. Desktop Color Separations (DCS) format, a version of the standard EPS format, lets you save color separations of CMYK images. You use DCS 2.0 format to export images containing spot channels.To print EPS files, you must use a PostScript printer.

References:

• Adobe Help Resource Center: Photoshop EPS format

Photoshop format (PSD)

Photoshop (PSD) - Photoshop format (PSD) is the default file format and the only format, besides the Large Document Format (PSB), that supports most Photoshop features. Because of the tight integration between Adobe products, other Adobe applications, such as Adobe Illustrator, Adobe InDesign, Adobe Premiere, Adobe After Effects, and Adobe GoLive, can directly import PSD files and preserve many Photoshop features.

References:

• Adobe Help Resource Center: Photoshop format (PSD)

ZIP

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.

References:

• Adobe Help Resource Center: About file formats and compression

CCITT

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.)

References:

• Adobe Help Resource Center: About file formats and compression

JPEG (Joint Photographic Experts Group)

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.

References:

• Adobe Help Resource Center: About file formats and compression

LZW (Lemple-Zif-Welch)

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.

References:

• Adobe Help Resource Center: About file formats and compression

RLE (Run Length Encoding)

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

References:

• Adobe Help Resource Center: About file formats and compression

File Compression

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.

References:

• Adobe Help Resource Center: About file formats and compression