Automatic Color Balance

P
Posted By
pjbw
Dec 1, 2006
Views
594
Replies
10
Status
Closed
It must be in Photoshop CS2 somewhere!
Paint Shop Pro 9 has a "Grey World Colour Balance" command which corrects any fluorescent brown cast in my photos perfectly, just by moving its slider from 6500K to 4200K. According to the manual it "…balances in a way that causes neutral objects to have approximately equal red, green and blue components.".
I cannot find anything in PS which works remotely as well even manually with curves, levels, gray points etc. but there must be something, mustn’t there?
If anyone is interested I can attach before and after .jpg’s of an image which is defeating me in PS and is simple in PSP.
"Grey World" is an unusual name but there doesn’t seem to be a plugin available. PS 9.0.2. Win XP Pro
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auto balance color

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RK
Rob_Keijzer
Dec 1, 2006
For what its worth, I always colour balance my shots in Adobe Camera Raw. (currently also, beta-wise in Lightroom).

I make a lot of product shots of bicycle components that must have their colour characteristics ported over correctly through to press.

I always shoot a grey balance card in the intended scene and lighting (Whibal, BTW) that serves as a reference in ACR.

In the absence of grey card shots one can always select something in the shot that resembles a neutral, but it’s next to guessing.

I check/correct white point and black in Curves, soft-proof in CMYK with gamut warning on, save or FTP, and then drink coffee and watch a real prepress technician (which I’m not) save my intended colours to the glossy paper that I occasionally see in my nightmares.

Rob
JZ
Joe_Zydeco
Dec 1, 2006
In Curves, did you experiment with its Options, such as Enhance Per Channel Contrast and Snap Neutral Midtones?
RS
Robert_Shomler
Dec 2, 2006
Have a look at Bruce Fraser’s creativepro.com article "Out of Gamut: Don’t Underestimate Photoshop’s Auto Color"

<http://www.creativepro.com/story/feature/17164-1.html>
C
chrisjbirchall
Dec 2, 2006
I can attach before and after .jpg’s of an image which is defeating me

You can post the image at <http://www.pixentral.com> and paste the html code here.
P
pjbw
Dec 4, 2006
I hope these two HTML’s work Ok. I found it very difficult to select the complete bits of code in Pixentral – only rarely would they scroll outside the box; probably Firefox…?
While I am working through "Out of Gamut…." this is my original 10.3MP jpg straight off the memory card but resized and compressed to Pixentral’s 2MB limit, complete with those blue smudges in some windows (lens and/or processor?):
< http://www.pixentral.com/show.php?picture=1eNbqrlJrMo8wXrVm3 vSJSb018Wlxs1>

This is it de-keystoned with Altostorm’s plugin, colour balanced with Grey World, shadows tweaked, and sharpened with Unsharp Mask all in Paint Shop Pro 9:
< http://www.pixentral.com/show.php?picture=121sZNrGl1aDhJA7kO O3VK37W8043>

I was especially interested in the splendid medieval vaulted ceiling, lit by a mixture of daylight and those floodlights at the top of the columns. I had opted for daylight colour temperature and there was obviously some camera shake.The best I was able to do in Photoshop lost most of the colour at the bottom half of the picture.
I was hoping there would be a quick fix in Photoshop but since I have some 120 pictures to do I will stick with PSP for now and continue to practise with PS.
When I go to another region of France next year I will certainly use RAW now that it is supported for my camera in Camera Raw 3.6 and allows adjustments to the colour temperature.
RK
Rob_Keijzer
Dec 4, 2006
I found it very difficult to select the complete bits of code in Pixentral – only rarely would they scroll outside the box; probably Firefox…?

Right click on the code and choose "select all". 🙂

This is what I did:

Perspective correction with Transform (Perspective).
Sharpened with "Focus Magic" (plugin) at 1px 150% New Curves adj layer, Grey balanced the plaster right from the door. Reduced opacity to what looked right (65%)
A secund Curves layer to tweak the contrast (luminosity blend) Flattened
Cropped (because of the "rised front" perspective shift:

< http://www.pixentral.com/show.php?picture=1K1hAiHzlfL6dViNmX z6warDFbTZ>
RK
Rob_Keijzer
Dec 4, 2006
I forgot to add that in this sort of photography I seldom use a grey reference. I tweak the colour balance and the curves so it resembles a certain atmosphere.

Rob
JJ
John Joslin
Dec 4, 2006
Nice job Rob!
RK
Rob_Keijzer
Dec 4, 2006
Thanks! But a good edit starts with a good photo, so the real credits go to pjbw.

Rob
P
pjbw
Dec 5, 2006
Thank you for the credit, Rob,
Thank you also for the the hint re Pixentral. As an ex-programmer I have a couple of suggestion to make to ‘Carlo’ when I send my donation.
I notice you felt the need to correct for barrel distortion. Almost the first thing I noticed when recording medieval architecture is that almost nothing is straight or rectilinear. Therefore I had to go away out of the box to find a camera which has (or rather ‘had’ – it is discontinued now, presumably not a big enough rip-off compared to D-SLR) negligible barrel and pincushion distortion throughout its zoom range in conjunction with a wide wide-angle lens. There is no point in my publicizing the model – you can see it in the Exif.
The Russian Altostorm plugin (£45.84 in August) for PS and PSP is a vast improvement on anything in PS and PSP for my work. It can de-keystone, correct barrel and pincushion distortion, allow adjustment of the aspect ratio and viewing level, and crop all in one 5-stage pass. Three cons: you cannot correct vertically and horizontally in a single pass but since there does not seem to be any image softening I can live with this, the option of a grid in stage 4 would help, and it would be nice if the sighting lines indicated when they were straight rather than my having to hold a ruler up to the screen (sounds horrible but I think the programmers were assuming that barrel and/or pincushion distortion would always be present – they would be right most of the time!).
I got nowhere with the grey reference (Curves, Options) in PS. Changes in ‘Select target midtone color’ were displayed in the dialog but were completely ignored in the Preview and also after I had Ok’d back out of Curves.
However, since PSP 9 opens Photoshop’s .psd files I looks as if I will be sticking to Bridge, Camera Raw and Paint Shop Pro 9 for the foreseeable future.

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