There are many image formats, e.g. JPG, BMP, PNG and PCX. The icon format is also an image format. Its file extension is .ico. The icon files can contain more than one image. This is why it's so usefull in some situations. There are different icon formats because operating systems use their own formats. Frontbase Image to Icon supports the Windows icon format.
When a user browses files in Windows it may, depending on the viewing settings, look like this :
When Windows shows the file list it checks the viewing settings and then determines which images to extract from the files' icons. When, for instance, a user looks at a file list with small icons, Windows extracts the images with the dimension 16x16 pixels from the icons. Also if Windows can show only 256 colors (8 bpp) it searches for images with 256 colors. However, if Windows can't find the appropriate image it chooses the closest one that fits the description.
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An example:
An icon file contains the following images:
The user looks at a file list in Windows which shows small (16x16) icon images and the computer can show only 256 colors (8 bpp). When Windows checks the icon files and can't find any appropriate image from the above icon file, it has to choose one, so it chooses image 1 because its dimension is closer to 16x16 pixels than to the dimension of image 2 and because it has the color depth of 8 bpp. |
When you make an icon file you should include at least the following dimensions and color depths: