PNG pronounced ping is a format for storing bitmapped (raster) images on computers. It was created originally to replace the GIF file format when it was announced that the companies who created the GIF format wanted royalties. PNG uses indexed colors and lossless compression (like a .GIF file), but without those copyright limitations; it cannot be animated like a GIF image.
PNG images are in many ways better than .GIF as they also include an 8-bit transparency channel, which allows the colors in the image to fade from opaque to transparent; GIF images only support fully opaque or fully transparent pixels. PNG supports palettes of 24-bit RGB colors, RGB images or greyscale or RGB images. PNG was intended to be able to transfer images on the Internet, not professional graphics, and so does not support other colour spaces (such as CMYK).
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The .ico file extension is a file format that is used by Microsoft Windows to display an image to represent computer icons, such as programs, shortcuts, Start Menu items or directories. To associate an image with a file in Microsoft Windows a .ico file must be used. An example of an icon is the small computer image associated with 'My Computer' or the Notepad icon that is associated with the Notepad.exe application within Microsoft Windows.
The .ico file type was introduced by the first edition of Windows and has slowly evolved in terms of maximum pixel size and the level of colour support. Windows 7 currently supports icon sizes up to 256 x 256 pixels at 32 bit (comprising 24 bit colour, and 8 bit transparency). However to ensure backwards compatibility with previous versions of Windows 8 bit versions are recommended.
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