Pulborough Computer Club
Saving Graphics Files
The Bad News
There are hundreds of different graphics file formats out there. It seems that every programmer who ever wrote a graphics program invented his own.
The problem is this. If your favourite graphics program uses its own proprietary file format and you email that picture to a friend, he or she will be unable to see the picture unless they have the same program. It's the equivalent of the Tower of Babel.
OK, I exaggerated. Most graphics programs can interpret several different file formats but none can interpret all.
The Good News
There is a esperanto, (well two and a bit actually), available to every user with internet access. By all means use your favourite graphics program's proprietary format for working on pictures in the privacy of your own computer, but always use one of the lingua franca for data transmission. Your graphics program should be able to do the conversions. If it can't, you really ought to get a better one.
JPEG (pronounced jay peg)
This format is well suited to photographic images which usually have lots of gradual colour variation. It's not so good where there are 'hard edges' in the image.
It's a lossy file format which is to say that some of the picture's information content is lost in the compression process. The quality level can be adjusted in most graphics programs, but please note that Paint Shop Pro uses the non-standard term 'compression level' instead. I've recently started using a program called Image Optimizer because it simultaneously shows the image before and after compression.
A word of warning though. Every time you open a JPEG image, amend it and save it in the same format, a little more degredation occurs. If you expect to be processing the image several times, it's best to save it in a non-lossy format during the intermediate stages, only switching to JPEG for publication. Suitable non-lossy formats are .pcx or maybe your graphics program's native format.
JPEG stands for Joint Picture Expert Group and JPEG files usually have file extension of .jpg or .jpeg .
GIF (pronounced with a hard g)
This format is well suited to clip art images which have blocks of uniform solid colour and well defined edges.
It's a loss free file format and no information is destroyed in the compression process. The resulting compressed file's size depends more upon the original picture's complexity rather than it's size. A large but simple logo will compress down very small. A small photographic image could even end up larger!
GIF stands for Graphics Interchange Format and has the file extension .gif .
PNG
GIF was devised by Compuserve which, after years of inaction, is now busy trying to collect royalties from corporate users. For this reason, the PNG (Portable Network Graphics) format has been devised to replace it.
Modern Internet browsers and email clients support it, but many users haven't upgraded and it's not universally supported as JPEG and GIF are. For this reason, its use is not yet recommended.
Graphics Programs
This is an incomplete table of what graphics programs can handle which formats.
| Program | JPEG | GIF | PNG |
| MS Windows Paint | No | No | No |
| MS Photo Editor (part of Office) | Yes | Yes | Yes |
| JASC Paint Shop Pro 6 & 7 | Yes | Yes | Yes |
| Adobe Photoshop 5.5 and higher | Yes | Yes | Yes |
| MGI PhotoSuite - all versions | Yes | Yes | Yes |
| Adobe Photo Deluxe 4.0 (Use File|Export) | Yes | Yes | Yes |