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Bluescreen technology involves filming actors in front of a primary color background, then setting that color to transparent, and compositing it with a background. The GIF and PNG image formats use alpha channels on the World Wide Web to merge images on web pages so that they appear to have an arbitrary shape even on a non-uniform background.
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]
The number of channels depends on whether the image is grayscale or color and whether it has an alpha channel. PNG allows the following combinations of channels, called the color type. A demonstration of the color depth in a PNG file, in bits per channel. Left: 8 bits; Right: 16 bits. Note the artifacts, adjusted contrast for clarity.
Color and grayscale: As discussed above, we can easily extract color and grayscale channels from an image. Note that color channels could be RGB, LUV or HSV. LUV color channels have shown to be most informative among all color spaces. Linear filters: This is a simple method for generating channels.
Here is an example of color channel splitting of a full RGB color image. The column at left shows the isolated color channels in natural colors, while at right there are their grayscale equivalences: Composition of RGB from three grayscale images. The reverse is also possible: to build a full-color image from their separate grayscale channels.
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 ...
The software mainly consists of a number of command-line interface utilities for manipulating images. ImageMagick does not have a robust graphical user interface to edit images as do Adobe Photoshop and GIMP, but does include – for Unix-like operating systems – a basic native X Window GUI (called IMDisplay) for rendering and manipulating images and API libraries for many programming languages.
Sometimes, you find a drawing or similar image useful for a Wikipedia article, that was saved as a JPEG but should have been saved as a PNG.JPEG is good for images where the color changes fluidly throughout the image, like in a photograph, whereas PNG files are good for images with relatively few colors, such as a drawing of a flag, a chart, or a map; note that sometimes SVG is better.