An application is not ready for use unless you have the proper icons for using into the application. Having the right icons for your application is not difficult if you have the help of a specialist or a specialized company to design the icons. The icon designer takes care of the whole design process starting from understanding what kind of icons are you looking for, designing them, submitting them for your approval and finalizing the icons to be used. The designer can also help you with choosing the most appropriate file types for the icons used into your application. But because you know better then anyone else the application for which the icons are, it is understood that you'll be one of the people involved in choosing the file type for the icons. This is why it is a wise thing to know few things about the most common file types for icons.
First of all we have to mention that the most common file types for icons are: ico, png, bmp, gif, icns. From the start we have to point out that ico file type is the one used by windows for its icons to assign an icon for every application. This ico file type is unique and it either assignees a system icon or presents individual types of files. All the files in your computer use icons depending on the file type they are. The ico files are very flexible in order the icons to change itself according to the file type. If the ico files are altered they will loose flexibility and will not be able to properly display the icons according to the type of the files. The ico file must remain with its factory settings. Another thing to be careful about when dealing with ico files, is when you plan to install any icon editor. During the installation process, some of this type of applications will ask the user if it is OK to make a file type association between the application and the .ico file type; in every situation the answer should definitely be no or else this option will mess up all the icons in your computer. In order to achieve the best quality for the ico files, certain parameters should be used depending on the operating system. For Windows XP it is recommended to use 32-bit ico files with Alpha Channel, parameters that allow using of full transparencies and shades. For the versions of Windows prior to XP the recommended parameters are 8-Bit ico files with 256 colors.
From the above mentioned file types, the icns are the correspondent of ico files for the MAC operating systems. They are a bit different from the ico files; icns files act like a container with more individual icon resources enclosed within it. So, with a single click the system accesses all the necessary icon resources that he needs. It is possible that for the previous versions of MAC this icns file type will not be recognized. So, for safety reasons, an older icn # resource should be included in the resource file in order to avoid problems. Another thing about icns files is that they are not like the traditional icon files, meaning their images are not displayed outside the icon, but the images are enclosed inside the files as data and to be able to view them you should actually open an icns file . Icns files are only used and recognized by the MAC operating system. To transfer these icons into more commonly used image image file types; there are special applications that can convert icns files into jpg, bmp, gif, files.
Another file type used for icons is png; This is used only for Windows operating system and it was designed to replace the gif format file, that was older and simpler, and the tiff format file that was rather complex. Png is a superior file type; if you want to display a photograph exactly like it is in its best quality, the png format should be your choice because it produces smaller files and allows more color. Png is also able to compress the image files to smaller sizes without altering the image, and if you want to recover the original image the compression is exactly reversible. Also, the png files allow more colors, enable drop shadows and, quite important, support partial transparency that can be used for various purposes. Png files are supported by most web browsers and various development environments. A useful trick for png files when they are used with Internet Explorer for windows: 32 bits png files with alpha channel should be converted into non-transparency png file with the preferred BG color; using png Behavior from WeBX is an alternative.
Gif file types are perfect for images that do not contain more than 256 colors and has large areas of uniform color, so gif file type is not recommended to be used for photographic images because they will not be shown in their best format. If the number of colors is smaller then 256 then there will be no problem for the gif file type to show the image exactly like it is. If the image has too many colors gif will use various algorithms to approximate the extra colors in the image. Gif format also compresses files but during compression it looses many of the colors. Gif compresses image files in two ways: either he reduces the number of bits needed per pixel or he abbreviates common patterns. Gif files do not support full transparency that is why it is recommended pastel colors or light tones to be used for the background whenever with gif files.
We have talked about the most commonly used file types for icons and pointed out some useful information that can be handy whenever trying to choose the right file type for icons.