TIFF
Tagged-Image File Format (TIFF, TIF) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format supported by virtually all paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images. TIFF documents have a maximum file size of 4 GB. Photoshop CS and later supports large documents saved in TIFF format. However, most other applications and older versions of Photoshop do not support documents with file sizes greater than 2 GB.
TIFF format supports CMYK, RGB, Lab, Indexed Color, and Grayscale images with alpha channels and Bitmap mode images without alpha channels. Photoshop can save layers in a TIFF file; however, if you open the file in another application, only the flattened image is visible. Photoshop can also save annotations, transparency, and multiresolution pyramid data in TIFF format.
In Photoshop, TIFF image files have a bit depth of 8, 16, or 32 bits per channel. You can save high dynamic range images as 32‑bits-per-channel TIFF files.
Bit depth (32‑bit only) Specifies the bit depth (16‑, 24‑, or 32‑bit) of the saved image.
Image Compression Specifies a method for compressing the composite image data. If you’re saving a 32‑bit TIFF file, you can specify that the file be saved with predictor compression, but you don’t have the option to use JPEG compression. Predictor compression offers improved compression by rearranging floating point values, and works with both LZW and ZIP compression.
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:
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.