Formats for digital photo:

If you print your images yourself at home or office, you can stick with the original format or use the PSD Photoshop format. If you send the photos to the local camera shop (or discount store) for printing, stick with JPEG - or, if they accept it, TIFF. Here are the pros and cons of the major formats that you should consider for photos:

PSD: Photoshop’s native file format is great for saving your images with the most flexibility. Because the PSD format supports all of Photoshop’s features, you don’t need to flatten your images - and keeping your layers lets you make changes later. If your file size is very large (4MB or larger), make a TIFF or JPEG copy before printing, flattening all the layers. Do not send PSD files to the local shop for prints.TIFF: Layered TIFF files are compatible only with Photoshop.

JPG: JPEG, as it’s called, is actually a file compression scheme rather than a file format, but that’s not important. What is important is that JPEG throws away some of your image data when it saves the file. Save important images in PSD or TIFF and use JPEG only for copies. When should you use JPEG? When sending images to a photo lab that doesn’t accept TIFF files and when sending images (perhaps by e-mail or on CD) to people who don’t have Photoshop. Unlike PSD and TIFF, you can open JPEG images in a Web browser and print from there. When saving JPEGs, the lower the Quality setting you choose in the JPEG Options dialog box, the smaller the file but also the more damage to the image

Large Document Format (PSB):
Really, really, really big pictures- over 30,000 pixels wide or long or both - need to be saved in the PSB file format.
Will you ever need this format? Consider that 30,000 pixels at a photoquality resolution of 300 ppi is 100 inches long. At a resolution of 85 ppi, more appropriate for a long banner to hang in a hallway, you’re talking about artwork that stretches almost 30 feet! Can your printer do that? If not, you probably don’t need the PSB file format. You could theoretically use a number of other available formats, such as DCS, PNG, and Photoshop Raw, but there’s no real need with the more common
and more versatile formats about which you just read.
You shot the image in Raw (or TIFF) and need to convert to 8-bit color if you want to save as JPEG, because JPEG doesn’t support 16-bit color.

Formats for Web graphics:

JPG: Use JPEG for photos. A smaller file downloads (and displays in a Web browser) faster, but a larger file generally looks better.

GIF: GIF is more appropriate for items like Web buttons and banners than it is for photos. If you save a photo that’s more than perhaps 100 pixels x 100 pixels in size, you might see some degradation of the image quality as similar colors become one color.
When you save an image as GIF, it can contain no more than 256 distinct colors. JPEG and the other common file formats can have thousands of different colors.

PNG: PNG comes in two types: PNG-8 (which is a substitute for GIF) and PNG-24 (which is a substitute for JPEG). PNG has a couple of advantages for Web designers, such as support for transparency, but not all Web browsers can display PNG graphics. Generally speaking, it’s safer to use JPEG and GIF.

series to be continued…in the next post