Photoshop processing uses grayscale?

[Abitconfused]

Internal Photoshop processing is obviously a number crunching exercise but I occasionally hear that Photoshop uses a grayscale gradient to process images. How can this be? Numbers are numbers where would the grayscale come in?

[wobert]

My understanding is this - An colour image is created from the 3 colour channels- Red Green Blue- The brightness of each colour channel is referred to as Luminance and luminance is represented in the camera and software as the greyscale. So three greyscales, each representing one of the colours. If you use editing software (such as Photoshop) it is easy to view an image as individual channels, and be able to selectively use one channel (a greyscale) to create masks or other adjustments. It is interesting to note that higher "bit rate" images have a far greater number of tones in the greyscale gradients (8 bits = 256 tones, 12 bit = 4096 tones) and when you save your nice RAW images (maybe 12bit or higher) as JPG files, they are compressed down to 8 bit. Hope I'm on the right track with an answer like this.