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Intermediate Photoshop - Correcting Color Shifts

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Picture of Intermediate Photoshop - Correcting Color Shifts
I'm sure a lot of us have come across color shifts in our photography, and they can be extremely frustrating.  This instructable is going to quickly go over why the shifts are there in the first place and then how to fix it in post. 

This method can be a little complicated, so take your time and try to practice, it will probably take a few tries to get it down.

You will need:
  • Photoshop (or similar editing program)

**NOTE: All photographs used in this tutorial were shot and retouched by myself

 
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Step 1: Why Does my Photo Have a Color Shift?

Picture of Why Does my Photo Have a Color Shift?
First of all, before we get into correcting color shifts, we have to understand them.  Most cameras these days have an automatic white balance setting to control this issue, but everyonce in a while it can be inaccurate.

Color shifts are caused by different color temperatures in light, we call these "Kelvin temperatures."  Daylight has a Kelvin temperature of 5000, and is the most neutral you can get your photo to look. 

Have you ever photographed something in your house under a typical house bulb and the whole photo turned out orange or yellow?  That's because typical household lights have a Kelvin temperature of about 3000, which can look yellow, but because the human brain is so sophistocated, it corrects this to daylight temperature for us.  Tungsten and flourescent light bulbs can also have a similar effect, where we don't see the shift, but our cameras do.

Tungsten bulbs tend to have a magenta shift to them, while fourescent bulbs can turn a photograph green.  Yuck! 
Make a video please.
fozzy131 year ago
I have this problem all the time with my Instructables pictures!! If I don't get the perfect shot, everything gets washed yellow.
This would be awesome as a GIMP tutorial though.. so that I can do it ; )
Try Colors-> Auto -> Color correction. Or Colors -> Color Balance -> slide the different sliders until you get what you want. I duplicated the sample picture correction by sliding the magenta to green a bit.
Awesome. Thanks for the help!! : )
There are also a lot of Gimp tutorials all over the web, and youtube videos.
KathyTackettPhoto (author)  fozzy131 year ago
I wish I could help you with that. :/ I'm very unfamiliar with GIMP. In fact, I had never heard of it until I joined this site.
kmpres1 year ago
Awesome instructible, thanks for sharing. I've often wondered how this black art worked. I have a question: Is it possible to derive a color photograph from a black and white one without "painting" pixels directly (colorizing)? It seems to me that color shifted photos look almost black and white so the steps ought to be similar. I have some pictures taken in the first half of the last century and would dearly like to see them in color without actually "colorizing" them. Is there software that can do this?
KathyTackettPhoto (author)  kmpres1 year ago
Unfortunately, no there isn't. :( If you were trying to turn a black and white photograph into a colored one without painting the individual colors in, the end result would be very monotone. instead of having, say the flower in the photograph be red, the whole image would be red.
ndr19681 year ago
Needs about "plus 5" red. One on the right has a cyan cast to it.
On my screen it looks a bit greenish. That's the problem, there was a time when we nailed the colour to a print on paper and the colour balance is different as AnubisAndIsis says below.
Now we mostly look at pictures via LCD screens and the colours differ from monitor to monitor.
Here in the lab we calibrate our monitors with an i1 from Gretag MacBeth and keep libraries of ICC profiles. I also use special software to colour correct and for KathyTackettPhoto's test image I get quite a different result. BUT....despite the science I would actually warm the colours a little in the final "perfect" result.
Photography is still an art, the photographer knows what sort of effect they want to get. Even if exact realism is required the photographer was there and knows what is real. Ultimately they produce the result they want to depict in the display technology they have at hand.
It is always a good idea to calibrate your monitor and keep the ICC profile backed up.
cc.bmpcc.bmp
Sorry about the duplicated image - some bug in the upload would not let me delete the copy.
triumphman1 year ago
I love that door! Looks like one I saw when I was in Switzerland! Thanks for bringing it back to my memory!
KathyTackettPhoto (author)  triumphman1 year ago
It's the front door of my friend's house! It's 400 years old!
A better approach is to check your endpoints first, then move curves only if there is a need to adjust tones. Changes in curves of any kind affect tones, which affects contrast, which you can see in your end result - although you've balanced the color, there is a loss in contrast in many of your three-quarter and quarter-tones. For offset printing, to avoid posterizing at the last printable dot, set the white points to around 1% MYK 2-3%C, and blacks from 80-90% CMY and 95% K, depending on your gray replacement and/or under color removal model. The C shift is required due to the natural inclination to perceive "bluish" as balanced, perfectly balanced numbers look reddish and muddy (and works better due to color contamination as a result of the limitations of printing pigments.)

You can then locate the 50% tonal areas and just note the balance - after adjusting the endpoints it should be fairly balanced. If not, use the hue/saturation tools to MOVE the colors, not bend the tonal curves.

The above is for optimum offset printing specs, you'd handle it similarly with RGB.
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