Alphakanäle

Alphakanäle, also known as alpha channels, are a component of an image that stores information about transparency or opacity. When an image is displayed, the alpha channel determines how much of the background should show through each pixel. A fully opaque pixel has an alpha value of 1 (or 255 in 8-bit color), meaning no background shows through. A fully transparent pixel has an alpha value of 0, meaning the background is completely visible. Values between 0 and 1 represent varying degrees of translucency.

This transparency information is crucial in digital imaging and graphics, particularly for compositing images. For example, in graphic design and web development, images with alpha channels allow for seamless blending of elements over different backgrounds without the need for a solid color border. This is commonly seen with PNG image formats, which widely support alpha channels. Video editing also heavily utilizes alpha channels for effects, overlays, and special visual elements that need to be superimposed onto a video stream.

The alpha channel is typically represented as an additional grayscale channel alongside the color channels (like red, green, and blue). When an image is saved, the alpha channel information is stored as part of the file. The interpretation and application of alpha channel data depend on the software or system rendering the image. Its presence significantly enhances the flexibility and realism of digital image manipulation and display.