Ask the Techno
By Jon Kenton
Q. I am sure I must be the last person on the planet with dial-up Internet, but I have finally decided to get a broadband service. I have looked at my local cable and telephone companies who offer broadband, but just heard about Muni Wi-Fi. What is this?
A. Muni or Municipal Wi-Fi is where a city deploys a wireless network across all or parts of its geography. The equipment is mostly outside, and if you are in the coverage area you can gain access inside your home, in the garden, and anywhere else in the city. An independent company usually constructs and manages the network. Some cities offer the service for free; others do charge, but rates can be lower. Here in the Valley, there is a Muni network in Tempe. Chandler and Gilbert are in the works.
Q. I volunteer at a local charity and am putting together a newsletter. All sorts of people have sent me contributions. The pictures and graphics seem to be in loads of different formats: JPEG, TIFF, GIF, PSD, BMP, etc. This is very confusing. Can you explain what they all are and how I manage them?
A. That could be a very long answer, but let me try to give you a quick primer lesson. The first thing you probably already know about images is that they can be very large. This has lead to the development of compression techniques to make them smaller. There are two basic types of compression. One actually removes data, thereby reducing quality; the other does not. They are known as lossy and lossless compression techniques or algorithms; I bet you can guess which is which. Most of the files you will deal with are known as bitmaps. Essentially, the data represents a map of individual pixels, and the value of each pixel is a color. The more colors, the more bits, and the larger the file. The popular formats are:
GIF and BMP, used primarily for graphics, shapes, clip art, logos, etc. BMP is a Microsoft Windows bitmap and is usually uncompressed, creating larger files. GIF, or Graphics Interchange Format files, are limited to only 256 colors and use a lossless compression.
JPEG, now the most commonly known file type and used by all digital cameras, is a lossy format, but can support up to 24 bits of color information per pixel (that’s over 16 million colors). Its benefit comes in a variable compression scheme that can dramatically reduce file size, but at a cost in quality. If you don’t compress too much, JPEG quality is more than acceptable and is overall a very efficient and flexible format.
TIFF is a very high-quality lossless format; however, unless you have a need to keep every last pixel intact and create giant poster-size prints, I wouldn’t recommend using it, as the files are huge!
The PSD file you mentioned is the format used in Adobe Photoshop’s image-editing software. It keeps lots of extra manipulation information along with the bitmap. It’s a must if you are a Photoshop user.
The easy answer to how to manage all these submissions is to ask all your contributors to stick to one format. JPEG would be the best. If you have to convert files, invest in some simple image editing software. Do check that all the basic formats are supported.