← Glossary Term
alpha channel
The extra layer in an image file that records how transparent each pixel is.
A normal image stores three numbers per pixel, for red, green and blue. An alpha channel adds a fourth: how opaque that pixel is, from fully solid to fully see-through. It is why a PNG logo can sit on any background without a white box around it, and why a JPEG cannot.
In AI image generation the distinction matters more than it sounds. Cutting a background out afterwards means guessing where the subject ends, which goes badly on glass, smoke and hair. Generating the alpha channel while the image is being made lets the model decide transparency directly.
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