One of the very useful features of the web is its capability to include images within documents and to handle other multimedia forms. While this is very simple to do through HTML when everything is set-up right, producing and/or locating images, decompressing them, and getting them into an acceptable format can be tricky.The purpose of this discussion is to provide an introduction to handling images and pointers to several useful sources.
Sources
There are only two sources of images: you either produce them yourself or you get them from some other source.To produce an image yourself, you are likely to use one of two methods. First, you may use a paint program to construct a graphic form. SuperPaint is a popular paint program on the Mac; similar software is available for PC and UNIX platforms. To produce an image for inclusion in a web document, you do so using the paint program in a conventional way. When you save it, specify an image format that is widely supported by web browsers, if your paint program provides this option. Currently, that means either GIF or JPG. If you don't have GIF or JPEG options, you can probably convert from the paint program's default format (e.g., PICT) to GIF or JPG using a conversion tool, as explained below.
If you are not familiar with image formats (few people are!), a good place to start is the WWW Consortium's graphic formats page. See, particularly, their compilation of Frequently Asked Questions (FAQs). It includes not only explanations about most of the topics discussed here but also sources of software to help with you with these tasks.
The second most likely way you are to produce an image yourself is to have a photograph (or other paper representation) scanned. This requires a physical device, called a scanner, that works something like a Xerox machine, but converts the photograph or other object being copied into digital form and saves it as a computer file. You can then copy that file to a disk and, subsequently, move it into an appropriate file where it can be accessed by a web server. Again, you should have the scanner software produce a GIF or JPEG file, if possible.
A third option is to use a digital camera that produces digital images directly instead of film images that must be scanned. However, these cameras are currently not widely available and produce images with relatively low resolution. Consequently, they will not be described further.
The alternative to producing an image yourself is to obtain it from some external source. Most likely, this will mean obtaining it from a source on the network using your web browser. Doing so raises a number of ethical and legal issues regarding intellectual property and copyright. I won't discuss those issues here except to say that if you plan to use someone else's image, particularly if there is any monetary aspect to your document, you should obtain their permission and acknowledge the source. For one organization's views on this issue, see Art on the NetImages obtained from the network come in compressed and decompressed forms. The most likely source of compressed images is from newsgroups, particularly those that include binaries as part of their names. The most likely source of uncompressed images is from collections provided by individuals or groups through conventional web pages. You can tell whether or not the images is compressed by its appearance in your browser: uncompressed images appear in a recognizable form and compressed images appear as unreadable sequences of characters.
Below are sources on the network that may have useful images
- Images
- Art on the Net
- Yahoo's ART list
- Clip-art newsgroup
- The Louvre, etc.
- WWW Virtual Library: Museums
- Software
- Mac graphics software
Decompressing images
If the image comes in a decompressed form, you can save the image in a file from the web browser. Subsequently, you would reference the copy stored in your file through a conventional IMG SRC tag. You could, of course, reference the original image from the source where you obtained it, but you have no guarantee that it will remain available. Additionally, an image for which you have the GIF or JPG form can be edited, enlarged or reduced, etc., through image editing software such as PhotoShop.If it arrives in your browser in a compressed from, you must decompress it before you can display it in a recognizable form or manipulate it. To do so requires a decompression tool. A popular one for the Mac is UU tool 232, and similar tools are available for PC and UNIX platforms. This is done by opening the file in the tool, selecting decompress from a menu, and then saving the uncompressed file (under a different file name from the original).
Converting between graphic formats
Currently, most web browsers can display images in a very limited number of formats. Netscape, for example, can only display images in GIF and JPG forms (as well as POSTCRIPT). If you obtain an image in an alternative form, such as PICT, you need to convert it to one of the above. Again, this is relatively straight forward. If the image is compressed, decompress it first. then use an image conversion tool. A popular one for the Mac is GraphicConverter, and similar tools are available for PC and UNIX platforms. Conversion is straightforward by reading in the file and then selecting the desired format as part of the save command.