GIF Optimized for Web
Although there are many graphics formats, GIF and JPG (and increasingly PNG) are the most common graphics formats on Web pages today. GIF is popular because it compresses well (makes smaller files), offers transparency (giving the illusion that the graphic is not a rectangle), and can be used for animation.
In addition to compression, GIFs on Web pages have a resolution of only 96 or 72 ppi (pixels per inch) since that is the resolution of most monitors. On screen, they look fine.
The low resolution and the process of compression results in smaller file sizes but also means that images lose quality. On screen, the loss of quality is less noticeable than when the image is printed.
Other Problems With GIFSoftware. Although standard for most of today's Web browsers, other software you use may not support the GIF format. To use a GIF image in those programs requires that you either convert it into another file format with a graphics program or use a product that allows certain Windows programs to recognize and use graphics formats they don't normally accept.
Backgrounds. A problem you may encounter when printing GIF files is the appearance of colored areas or backgrounds that didn't show up on the Web page. GIF files allow the creator to specify a certain color as transparent. By making the background of an image transparent, it looks as if it is not really a rectangular box.
However, once imported into your word processor or Desktop Publishing program the software sees the background as red, or blue, or whatever color was originally set to be transparent. If the transparent color was white you may not notice any difference, if not, you can end up with some unwanted color in your clip art. (See the sidebar image for an example)
To get rid of the unwanted background color you'll need to open the file in your paint program and fill the background (or other area) with a different color (such as white). However, due to anti-aliasing (a process that 'smooths' the edges of images) you will probably still have a slight 'halo' of color around the very edges of the image. To get rid of the halo you could zoom in on the image and recolor the individual pixels - but that is a lot of detailed work, especially considering the other print limitations of GIF files.
Print Better GIF
Although not foolproof, if you really want to use a GIF image from a Web page on a printed document, you can try one of these tips:
- Make it smaller. Resize the GIF smaller (height/width) and it may look better. What you are doing is squeezing the same number of pixels into a smaller area.
- Blur it. Blur the image slightly in your paint program. Or add a touch of 'noise' -- a common filter/effect in paint programs. Yes, it alters the appearance of the image somewhat but it may also make it look better when printed. I've had a little bit of success doing this - other times it just makes matters worse.
- Increase Image Resolution. Guide Sue Chastain describes software and techniques to make images bigger without a major loss of quality
Better Graphics Formats for Printing: TIF, EPS, PCX, WMF, etc.
If GIF images don't print well, then what kind of graphics are good for your newsletters and greeting cards? There are dozens of other formats, each with its own strengths and weaknesses. Some programs even have their own formats designed specifically for use in their software.
There are two basic types of graphics: vector and bitmap. Vector images are constructed from math equations for lines and can shrink and grow with no distortion. Bitmap images are made of little dots of a specific size. If you try to resize the image (especially enlarging it) those dots can become distorted.
Here's an incomplete reference chart and a few usage tips:
- vector/metafile : WMF, EPS, CGM, AI (Adobe Illustrator native format) CDR (CorelDRAW native format)
- can usually be resized larger and smaller with little if any loss of detail or quality
- usually use a drawing program (such as Illustrator, Freehand, or CorelDRAW) to create and edit
- metafile formats (including WMF and EPS) are a type of vector graphic that may include some bitmap elements such as a low-resolution bitmap preview image
- bitmap : GIF, BMP, PCX, TIF/TIFF, JPG, PICT
- composed of a fixed number of pixels (dots)
- resizing bitmap images can result in 'jaggies' - ragged edges
- usually use a paint or photo-editing program (such as Photoshop, Photo-Paint, PaintShop Pro) to create and edit
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