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By Root 1765 0

will recognize and contain all known Photoshop features, but so too will the TIFF and PDF file formats. However, there are several reasons why I find it preferable to save the master images using the PSD format. Firstly, it helps me to distinguish the master layered files from the flattened output files (which I usually do save as TIFFs). More importantly, when saving layered images, I generally find the PSD format is faster and more efficient compared with using TIFF. The native Photoshop format is usually the most efficient format to save with because large areas of contiguous color, such as a white background, are recorded using an LZW type of compression that makes the file size more compact, but without degrading the image quality in any way.

Smart PSD files

Adobe InDesign and Adobe Dreamweaver will let you share Photoshop format files between these separate applications so that any changes made to a Photoshop file will automatically be updated in the other program. This modular approach means that most Adobe graphics programs are able to seamlessly integrate with each other.

PSB (Large Document Format)

The PSB file format is provided as a special format that can be used when saving master layered files that are in 32-bits per channel mode and/or when you need to save files that exceed the normal 30,000 × 30,000 pixel dimensions limit in Photoshop. The PSB format has an upper limit of 300,000 × 300,000 pixels. However, the only photographic application I can think of where you might need such a large file would be if you were creating a long panoramic image. Even so, a lot of applications and printer RIPs cannot handle files that are greater than 2 GB anyway, but there are exceptions, such as ColorByte's ImagePrint and Onyx's PosterShop. For this reason the 30,000 × 30,000 limit has been retained for all existing file formats in Photoshop, where the TIFF specification is limited to 4 GB and the native Photoshop PSD format is limited to a maximum size of 2 GB. You also have to bear in mind that only Photoshop CS or later is capable of reading the PSB format.

Saving 16-bit files as JPEGs

For those who prefer to edit their images in 16-bit, it always used to be frustrating when you would go to save an image as a JPEG copy, only to find that the JPEG option wasn't available in the Save dialog File Format menu. The reason for this is because 16-bit isn't supported by the JPEG format. With Photoshop CS5, when you choose Save As… for a 16-bit image, the JPEG file format is now available as a save option, whereby Photoshop carries out the necessary 16-bit to 8-bit conversion as part of the JPEG save process. This now allows you to quickly create JPEG copies without having to temporarily convert the image back to 8-bit. Note, however, that only the JPEG file format is now supported in this way.

TIFF (Tagged Image File Format)

The main formats used for publishing work are TIFF and EPS. Of the two, TIFF is the most universally recognized, industry-standard image format. TIFF files can readily be placed in QuarkXpress, InDesign and any other desktop publishing (DTP) or word processing documents, but this does not necessarily imply that it is a better format, because the PDF file format has also been gaining popularity for DTP work. The TIFF format is more open though and, unlike the EPS format, you can make adjustments within the DTP program as to the way a TIFF image appears in print.

Labs and output bureaux generally request that you save your output images as TIFFs, as this is the file format that can be read by most other imaging computer systems. If you are distributing a file for output as a print or transparency, or for someone else to continue editing your master file, it will usually be safer to supply the image using the TIFF format.

TIFFs saved using Photoshop 7.0 or later support alpha channels, paths, image transparency and all the extras that can normally be saved using the native PSD and PDF formats. Labs or service bureaux that receive TIFF files for direct output will normally request that a TIFF