RGB Channels

Drop a photo and pick a channel. The curtain on the image compares the channel against the original.

How many channels are in RGB

Three: red, green, and blue. Each pixel has its own value from 0 to 255 in every channel, and the color of the pixel adds up from the three values.

PNG and WebP can have a fourth channel, alpha, which stores transparency: white in it is opaque, black is transparent. JPG has no alpha channel.

Grayscale or color

Photoshop and GIMP show channels in shades of gray: the lighter the pixel, the more of that color it holds. A blue sky is bright in the blue channel and dark in the red one.

You can view a channel in its own color on black, which makes it obvious which channel is on screen. Three such frames stacked together give back the original photo.

All channels and separate files

"All channels" lays out a grid on one frame: red, green, and blue, with alpha in the fourth cell if the image has transparency, otherwise the image itself. The cells are half size, so the grid stays the same size as the image.

The "Each channel as a separate file" button saves full-size channels as an archive: name-red, name-green, name-blue, and name-alpha for images with transparency.