Photoshop Files and Formats

by David Peters

You might find yourself wondering what image file formats Photoshop will open or save in. What are the advantages or disadvantages of each?

Simply put, Photoshop has the ability to open and save a variety of graphic files. Let’s take a look at the more popular ones.

One thing to keep in mind is that when you open an image file other than a Photoshop one, the other image will default to the background layer.

1) .psd, .pdd, .eps – Photoshop File

This format saves the information in all the layers. This is the best format to use if you are going to perform further work on a picture, however the file size can be quite large. It is best to save your work in the most up to date Photoshop format existing. An example would be if you have Photoshop CS and are sent a Photoshop 7 file, you should save it as a Photoshop CS file to maintain any elements that may not be supported by Photoshop 7.

2) .jpg, .jpeg .jpe

This format compresses images to a point that information such as details and color subtleties are lost. You can select how much you want to compress the image. Good format for use on the web with small file sizes and millions of colors.

3) tif, .tiff

Most common in use with early scanners. This format will generate high quality images, but very large files. Not for use on the web.

4) .gif

Pronounced both “Gif” and “Jif”, this file is one of the most popular for web graphics as it loads quickly. 8 bit format (256 colours max.). It has possibilities for transparent colour and animation.

5) .png

For use on the web, this is a new format that is meant to replace both gif and jpeg. Files are compressed, millions of colors and transparencies supported. It compress in a different way than jpeg, and has advanced possibilities, such as alpha channel (opaque or partly transparent colors). The downfall is that Internet Explorer doesn’t support these. In 8 bit (256 colors) mode it compresses better than gif.

6) .bmp – Windows Bitmapped Image

Windows bitmapped image. Used by Microsoft Windows applications. Good quality, large file size. Not for use on the web.

7) .wmf – Windows MetaFile

Useful for clipart, and can be used to make large area, small sized background files.

8) .pcx

This older format is for general purpose and is basically obsolete now. Not for use on the web.

9) .psp

This format is an internal format for Paint Shop Pro and is useful if you need to swap files between these two applications.

10) .pcd – Kodak PhotoCD Format

Kodak PhotoCD format, used with Photo Developing – although most photo processors will save your photos as jpegs if you ask them to.

11) .pdf

Portable Document File. Adobe’s file system that allows electronic cross platform sharing of documents.

Now the question: What is the best format for web graphics: gif or jpeg?

The general rule of thumb is to use gifs for diagrams, line drawings, illustrations, and images that contain large areas of flat colour, and jpegs for photographs and images with continuous colour tones. The jpeg format has a very good compression rate, but compression reduces the quality of the image, so it’s best to experiment with the tools in Image Ready until you have the optimal quality/file size. The gif format, on the other hand, has a smaller file size – but a limited range of colours.

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