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A color spectrum image with an alpha channel that falls off to zero at its base, where it is blended with the background color.. In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. [1]
In computer graphics, pixels encoding the RGBA color space information must be stored in computer memory (or in files on disk). In most cases four equal-sized pieces of adjacent memory are used, one for each channel, and a 0 in a channel indicates black color or transparent alpha, while all-1 bits indicates white or fully opaque alpha.
In addition, transparency is often an "extra" for a graphics format, and some graphics programs will ignore the transparency. Animated PNG 8-bit transparency. Raster file formats that support transparency include GIF, PNG, BMP, TIFF, TGA and JPEG 2000, through either a transparent color or an alpha channel.
The alpha channel stores transparency information—the higher the value, the more opaque that pixel is. No camera or scanner measures transparency, although physical objects certainly can possess transparency, but the alpha channel is extremely useful for compositing digital images together.
PNG offers a variety of transparency options. With true-color and grayscale images either a single pixel value can be declared as transparent or an alpha channel can be added (enabling any percentage of partial transparency to be used). For paletted images, alpha values can be added to palette entries.
where a is the value of a color channel in the underlying layer, and b is that of the corresponding channel of the upper layer. The result is most typically merged into the bottom layer using "simple" (b over a) alpha compositing (making the actual formula f ( a , b ) = a l p h a ( b , a ) {\displaystyle f(a,b)=alpha(b,a)} ), but other Porter ...
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Alpha mapping is used when the given object's transparency is not consistent: when the transparency amount is not the same for the entire object and/or when the object is not entirely transparent. If the object has the same level of transparency everywhere, one can either use a solid-color alpha texture or an integer value.