Whats the point of Channels?

Shane

Shane

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Shane
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What is the point of Channels? What are they useful for? :shrug:
 
Click me!

First result in Google for "Photoshop Channels".
 
Shane said:
Thanks for the link :D but it doesn't really tell me what the point of Channels are :thinking:
Click to expand...

It kind of does. They are not there as a processing tool but as part of how cameras work. Every time you take an image you are taking three images that get merged together to create the shot you see.

One is red, one is green and one blue. Or as we are all used to seeing it, RGB.

Each channel holds the info for it's own colour and the composite is the full colour version that the camera outputs.
 
So if they're not there for processing, why even have them in Photoshop?
 
Because that's what your image file is. A bunch of pixels with each one representing a brightness value on each of the RGB channels. To allow you to have to have control over the images you manipulate, PS needs to be able to control each pixel. :)
 
okay, i think i'm starting to understand :thinking:
Could you give me an example of why i would use channels to manipulate an image, sorry for all the questions, I'm just not seeing the use yet :shrug:
 
Use the red channel at the start of a B&W conversion, for a more dramatic sky.

Split to channels, discard all but the red and work on that.
 
photon said:
Use the red channel at the start of a B&W conversion, for a more dramatic sky.

Split to channels, discard all but the red and work on that.
Click to expand...

Okay thanks, i'll give it a try :D
 
photon said:
Use the red channel at the start of a B&W conversion, for a more dramatic sky.

Split to channels, discard all but the red and work on that.
Click to expand...

If i discard the blue channel, i'm left with a cyan and magenta channel.

Why am i not getting this?? :'(
 
Shane said:
If i discard the blue channel, i'm left with a cyan and magenta channel.

Why am i not getting this?? :'(
Click to expand...

Sounds like you're getting in a mucking fuddle. :D

What are you actually trying to do?

An image is made up of different colours. Either 3 colours (red, green, blue) or 4 colours (cyan, magenta, yellow, black). When laid on top of each other they create the colour image you see on your monitor or the colour image you see in a magazine. RGB is used in the digital world such as photography, television etc. and CMYK is used in the print trade to produce magazines, brochures etc.

A photoshop 'channel' is just another word for a colour or seperation that is used to make up an image.

Your image should be made up of RGB or CMYK, not a mixture of both. So I don't get how you're ending up with a cyan and magenta channel when you delete a blue channel. :shrug:
 
I'm trying to figure out what the use is of working on only one channel.

If i delete the blue channel, it changes the other channels to cyan and magenta.
 
197.jpg


After deleting the blue channel
250.jpg
 
I wouldn't recommend deleting channels as you lose the information contained in that channel. Try using the channel mixer to mix the amount you use the info from each channel. For example to only use the red channel, reduce the others to 0% and to avoid the colours changing tick the monochrome box.
 
Good thread/question, I'm learning something as well here :thinking:
 
Channels are so important for colour correction - if you really need to get the colour spot on for an image, eg. skin tones in a portrait. then inspecting & correcting each individual channel will work wonders whilst maintaining detail (pores, etc)

They also allow you to select each luminosity value for the R G & B values of your image - hold Apple + Click on the channel thumbnail (think it's CTRL + Click on a PC)
This has unlimited possibilities for editing tones in your image - eg. avoid the very bright areas to avoid blowing the highlights in Post process stages.

Try opening a portrait & checking out the blue channel compared to the red - you can really see what you need to work on in an image based upon the channels view.
People tend to vastly underestimate the uses of channels unless in the photo retouching business imo.

Channels can also be used as masks to make precise selections that are much more accurate than the selection tools.
 
Here's a link which demonstrates working with the red channel for B&W conversion.
The terminology and any scripts are relevant to Paint Shop Pro.

http://www.gdargaud.net/Photo/BlackWhite.html

[Image][Split Channel][Split to RGB] and keep only the red channel (or better, start from a black and white picture taken through a red filter);

apply [Adjust][Brightness and Contrast][Clarify] twice at a setting of 4;

run the [Adjust][Brightness and Contrast][Histogram Adjustment] with both Low and High clip limits to no more than 0.01% and the Gamma so that shadow details are just visible (something like 1.20);

convert to [Image][Increase Color Depth][16 Million Colors];

[Adjust][Hue and Saturation][Colorize] with Hue at 160 and Saturation at 15 to 20;

[Effects][Sharpen][Unsharp Mask];

and finally back to [Image][Greyscale].
 
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