Working with channels?

[David M]

Hi all,well I`ve been playin around with photpshop on and off for about 2 years.
I have most of the basic`s ,but I cant get my head round working with chanels.
It`s frustrating because a lot of the problems I see in retouching could be sorted by "fixing the channels".
Frankly I feel lost in the whole "channel" thing.
I`ve tried to understand them by reading how you guys/girls fix channels,but I`m so lost.
Please is there anywere I could find a step by step guide to working on channels?

[ericwn]

take a look at scott kelby's book the photoshop channels book

[David M]

Does no one on the forum have any ideas?
Some on line tutorials?
I found jakaleena`s tutorial on how to replace a channel,and was able to carry this task out,but I get confused when I read about "the blue channel had a lot of damage" etc..
When I switch an image to lab colour,and check the channels,to me all the channel`s looked damaged i.e if there were spots on the photo,it comes through on all the channels.
Sorry I know I sound like an idiot.

[Swampy]

I second Ericwn's Kelby's book suggestion. It was hard for me to understand the concepts (anybody can follow a step by step tutorial, but grasping the why's and wherefores is not as simple) and Kelby's readable and witty dialog makes comprehention much easier.

[Cameraken]

Hi David

I see you have found Jakaleenas tutorial
http://retouchpro.com/tutorials/?m=show&id=23

Next you could try this
http://www.photoshopgurus.com/tutorials.html

Scroll down to Channels explained. PDF

However there are loads of threads here which you could read through. Just search for ‘channels’ and you will find 934 examples such as these

Here is one with a damaged blue channel
http://www.retouchpro.com/forums/sho...light=channels

And another
http://www.retouchpro.com/forums/sho...light=channels

Hope this helps.

Ken.

[David M]

Originally Posted by Cameraken

Hi David

I see you have found Jakaleenas tutorial
http://retouchpro.com/tutorials/?m=show&id=23

Next you could try this
http://www.photoshopgurus.com/tutorials.html

Scroll down to Channels explained. PDF

However there are loads of threads here which you could read through. Just search for ‘channels’ and you will find 934 examples such as these

Here is one with a damaged blue channel
http://www.retouchpro.com/forums/sho...light=channels

And another
http://www.retouchpro.com/forums/sho...light=channels

Hope this helps.

Ken.

Thx cameraken,I`ve found the retouch pro threads,but not the photoshopgurus one.
The retouchpro threads are good but a little to detailed for me at this moment(sorry).
I also found a tutorial called "rbstains" which looks great,I think the concept behind channels is the thing that has me confused.
(Thx swampy,your right about the "concept thing")
Thanks for taking the time to answer my question(one you must get 100s of times)

[byRo]

Originally Posted by David M

......but I get confused when I read about "the blue channel had a lot of damage" etc..

If you are retouching a coloured photo the blue channel is the least important. As such, it often gets badly preserved in image treatment (JPEG conversion, scanning etc.). Luckily it's easy to fix - just a general surface blur will usually suffice.

If you are working on a Black/White photo (restoration) then you have three colour channels when you only need one greyscale channel. So, in this case, you can pick and mix the good ones and throw away the bad ones.

Originally Posted by David M

When I switch an image to lab colour,and check the channels,to me all the channel`s looked damaged i.e if there were spots on the photo,it comes through on all the channels.

If the damage is basically in the Blue channel, then switching to LAB will definitely make things worse as the noisy information from the Blue channel gets used when generating all three LAB channels.

Originally Posted by David M

Sorry I know I sound like an idiot.

No, idiots are the one's that don't ask.

Channel trick (for portraits)....
Look at the three channels in turn:

RED: smooth glow in the skin areas;
GREEN: looks like a black/white photo;
BLUE: grunge.

Set up a channel mixer layer, mark the monochrome box, use Red 30%, Green 60%, Blue 10% and set the blending mode to Luminosity. (Nothing happened yet)
If you increase the Red mix (decreasing the others accordingly) you get a smoother look; increasing the Blue it will get harsher.
(The two examples attached are rather exaggerated)

Rô

[Cameraken]

Hi David

Yes. I forgot about Russell Browns ‘Digital Stain Remover’ that was very good but I can no longer find it. Is it still available?

You may also find this link useful.
http://members.ozemail.com.au/~binaryfx/links.html

But after Rô’s great explanation you may not need it.


Ken.

[palms]

Originally Posted by byRo

No, idiots are the one's that don't ask.

Rô

That's me thank you for info printed off to be studied

Palms

[imann08]

I don't know how far along in general PS knowledge you are but the Margulis books are very good. They are just very advanced and can be difficult. You get through his books and you will know channels.

You can improve the contrast of an image by using Apply Image on a duplicate layer to insert the best contrast channel in place of the two lesser ones and then changing the layer blending mode to luminosity. There are many other ways to solve both contrast and color problems by choosing the best blending mode in your blend, I just don't know if I could do them justice. I haven't read Kelby's book so I can't vouch for that but I would trust the opinion of those who did.