The three most commonly used image formats on the web and the Internet are Gifs, JPGs and PNGs. All these image formats use a compression algorithm to decrease the file size of the image so that the images load quickly in web browsers. The three images formats use different compression algorithms because of which they compress images differently.
For example, the gif image format is more suited for line-art and the jpg image format is best for photographs. You can find details on which format to employ for your images in separate articles – When to use GIFs and when to use JPGs, When to use the GIF format and When to use JPGs. It goes without saying, that since images are compressed, their quality is compromised.
Oh, Yes! Each of these image formats employ different compression algorithms, the results of which renders images differently. For example, the GIF image is more suited for line-drawings, or image with flat color while photographs are better saved as JPGs. The JPG algorithm compresses complex images like photographs very well and the GIF algorithm does a good job of flat color images. You can learn more about the different formats in their individual sections – Gifs and JPGs.
Image, like almost everything else, are included on web pages using HTML tags. The HTML tag for images is <img> that has several attributes via which you can specify the image height, width, border, alignment and even a short text description. You can learn more about the HTML <img> tag in the HTML tutorial.
You can create images for the web using any of the software mentioned in the Software section. Before choosing an image editing software, be sure to understand what all it can do. Some programs are more suited to work on photographs (photo touch-ups and embellishment), while others let your create images from scratch. I suggest that you download demo copies of graphics software and use them for a few days, which will help you decide the ones that suit your requirements; you can then go ahead and purchase those programs.
In addition to images that you create using dedicated graphics software and programs, almost all server-side languages such as PHP, ASP, Perl etc. allow you to create images from scratch using several in-built functions or external libraries. A typical use of creating images using server-side languages would be developing graphs of the number of hits a web site gets. For example, one can create graphs in GIF format by reading the web log using PHP.
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