By kind permission of Crikey over at the WZ2K forums, I have been practicing on a few family photos, here is my first offering:
http://pickledegg.pwp.blueyonder.co.uk/critique/critique.htm

This photo was very interseting to work on - It doesn't appear to follow the theory that i have learned.
I was told that to remove a cast you choose a neutral colour/colours and examine the rgb values to find the dominant channel. My final adjustment, after removing the majority of the cast, was to further reduce the blue channel, even though it did not appear dominant with the eyedropper. This did the trick.

Do some photos defy this convention and require the use of a good eye? :blank:

Limepickle

Nice family photo. I feel your final result still has a slight yellow cast. I did one minor tweak with a Color Balance Adjustment layer to increase the blues just a tad. (My settings were -7,0,+20)

This seemed to restore some blue to the gray suit, and the little girl's dress and really brighten the red in the other little girl's sweater.

Could be just a matter of personal taste though.

hi LP,

nice job.

i agree with swampy, though; too much yellow (nice job, dee dee!).

the easiest way i know of to remove a single color cast that exists across the entire image is with channel mixer or something like the plugin Fast Fix.

Craig

Craig, Thanks for the Fast Fix tip. I didn't have it, but just downloaded it and it really looks good.

dee dee

Simple colour correction using Curves Adj Layer.

Sampler on man's grey jacket, and white shirt collar.

Adj Red mid point for Grey, also 3/4 point down.
3/4 point for green up, lock point just below to ensure adj to hilights only.

A good place to start, but Gary, looks like you still have some green tinge in the skin tones.

I really didn't agree that there was too much yellow, UNTIL I looked at it on another monitor, and yes you're quite right. Defnite yellow tinge!

Hmm, is there any way of calibrating ones monitor to a 'standard'? I'd be interested if anyone knows if its possible.

Thanks folks!

Limepickle

I don't know that you can really define "standard" from one person's computer to another, but there are "specifics". For example. I know the Icc profile of my color printer's work space (they were kind enough to provide it for me and most good print shops will.) Color is so dependent on so many things.

I can work in standard Adobe RGB for most of the stuff like cloning, cropping etc., but when I get finished and convert to CMYK for my printer's high resolution platemaker, I use their color space (icc profile) then tweak final curves on my monitor to suit my eye on my screen. (I use an Apple Studio Display) and 99% of the time I get exactly what I was expecting. I also know that I sometimes have to compensate in the blacks for dot gain, but I've worked out a system that works for me. and my local printer.

dee dee,

you're welcome. just be careful with Fast Fix. when working with the numbers, they wont match up to ps or psp's numbers. and the preview image tends to distort the actual colors you're doing to wind up with. other than that, it's a great fast fix :)

and you mentioned 'dot gain'. i've only a very vague idea of what that is. is that a compensation for extra or removed dark dots when converting to a print mode?

limepickle,
there are commercial programs you can use. i've seen them mentioned on the forums. there are also links to web sites that have small apps or pages for correcting your monitor to some extent. i believe you can also calibrate a profile to match your own printer. and if you're using a Mac, there is apple's colorsync program. i just recently tried to find kodak's, but couldnt. it might have been discontinued. (?)

and dee dee (swampy) mentioned the icc. there is also a french one, the cie. you could look both of those up on the web and see what you find. i know little of either.

Craig

Craig..

Dotgain is allowing for the absorption and spread of the ink on the paper. Some papers (such as vellum bristol) soak and spread the ink more than high gloss clay coated or enamel paper.

dee dee

hmm, ok, not what i thought it might have been then. so, why would you have to 'compensate in the blacks for dot gain,..' ? do the blacks saturate more or less than the other inks?

Craig

Wow... Why Black....Think about it Craig...

We talk about 256 "shades of gray". So what does gray consist of in terms of putting the image on paper? Black (ink) and White (paper). Shades of gray in printing are represented by dots of ink or toner. To simplify, solid black consists of big dots printed close together, light gray conisists of smaller dots printed further apart (half toning)

The same basic theory applies when printing four color process (CMYK). Color=ink, White=paper. Other factors come into play in printing such as the resolution capability of the output device, paper absorbtion. Black is the "evil" color because it is used to define the shadows and midtones of all colors. Being able to control black gives you control of all the colors.

Here's an excellent site that explains how to set up PhotoShop to compensate for dot gain http://www.techcolor.com/help/dotgain.html

Hi everybody,

I am a new member of the forum from brasil. Your work is very nice. I just think you need to remove a bit of the red yellowish cast of the image (wich can be done by decreasing a little bit of the red channel curve on its mid range with a curves ajustment layer. after that, simply contrast the image a little bit - on the same curve, by increasing the entry level on the bottom of the RGB curve to 10 and decreasing the top of the curve to 245 (that will contrast the image a bit). After that I did a slight sharpen with a high pass / overlay layer on top of it. Hope you like the suggestions :square:

george rutherford
www.seagullsfly.com

Thanks rutherford,

on the subject of colour casts, do you think THIS (http://pickledegg.pwp.blueyonder.co.uk/critique/critique2.htm) has a slight blue tinge to it?

I can't pinpoint it. ( Ignore the patching work its only just been started. )

I am starting to get the hang of colour correction, although I still have a way to go.

Also, I'm losing the detail on the dark areas, how do I prevent this?

Any suggestions on curve methods here folks, along with the thinking behind your ideas?

Thanks

LP

LP

You're almost there. There is not enough red so it's heavy on the blue AND green. Do a curves or levels adjustment layer and use the white eye dropper to click in a white area of her shirt. This should bring up the reds.

Good stuff:
Do a curves or levels adjustment layer and use the white eye dropper to click in a white area of her shirt.
I assume you mean on the red channel?

Sorry... no, on the RGB channel

dee dee,

thanks for that site link. the first few lines explained dot gain: When working with screens of ink, a designer must always remember that things tend to get darker on a printing press. This happens when the ink absorbs into the paper and spreads outward, making each dot spread out and grow larger. ... the dot gains. ok.

Craig

What about now, ignore the stains and blotches, I'm concentrating on colour cast.

Hows this?

LINK (http://pickledegg.pwp.blueyonder.co.uk/critique/critique2.htm)

LP, Much Better! :-)