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Forums Lobby MASTER YOUR TOOLS - Hardware & Software Digital postprocessing & workflow (Public) topic #55
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Subject: "Software tungsten light correction" Previous topic | Next topic
JustSomeGuy Basic MemberWed 15-Nov-00 01:17 AM
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"Software tungsten light correction"


Cary, US
          

I obviously need to take a class in color theory, but before I do that... I was playing with a scanned scene, one taken with tungsten light and one taken with flash. I don't have Photoshop per se, but I do have a software package that lets me play with color both through RGB channels and HSB. I was able to correct some of the color shift due to the tungsten light, so that my whites looked white. I was also able to shift the hue so the reds looked red, but ultimately my greens turned out blue.

I understand that Photoshop has the ability to apply somewhat standard filters to images. Can you apply, say, an 80A to an image? If you can, what sorts of correction does this actually apply in terms of RGB(I) and or HSB?

- David Schmidt

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: Software tungsten light correction
Mikepoison
15th Nov 2000
1
Reply message RE: Software tungsten light correction
JustSomeGuy
15th Nov 2000
2
     Reply message RE: Software tungsten light correction
Mikepoison
17th Nov 2000
3
          Reply message RE: Software tungsten light correction
JustSomeGuy
22nd Nov 2000
4
               Reply message RE: Software tungsten light correction
Mikepoison
22nd Nov 2000
5

Mikepoison Basic MemberWed 15-Nov-00 04:59 AM
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#1. "RE: Software tungsten light correction"
In response to Reply # 0


Amsterdam, NL
          

The object of the filtering is to turn the coolness of the tungsten lighting into a warmer, more natural feel. This can usually be done by first turning the image a bit more amber with a color balancer, adding a color that rangest from yellow orange to yellow to te entire image. After that, it is often more a question of getting the right brightness/contrast settings to make the scan on the screen look like the photograhp placed on/in the scanner.

filters that adjust the coloring of tungsten lights (3200K) shot on normal light film (5500K) are that particular color so that the blue is partly filtered out of the picture. Therefor it is also very easy to, if the program supports it, make a layer of 80a Blue, and then creating the difference of it and the original scanned image.

Mike K.

"The world will not be quantified on celluloid... But I'll be damned if I don't try!"

  

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JustSomeGuy Basic MemberWed 15-Nov-00 11:48 PM
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#2. "RE: Software tungsten light correction"
In response to Reply # 1


Cary, US
          

So I guess that's my question... what does an 80A filter do in Photoshop? red = red * x%, green = green * x%, blue = blue * x%?

- David Schmidt

  

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Mikepoison Basic MemberFri 17-Nov-00 06:25 AM
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#3. "RE: Software tungsten light correction"
In response to Reply # 2


Amsterdam, NL
          

Give me a few days to borrow an 80A filter from somewhere, and let me get back to you on that one =)

Mike K.

"The world will not be quantified on celluloid... But I'll be damned if I don't try!"

  

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JustSomeGuy Basic MemberWed 22-Nov-00 08:29 PM
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#4. "RE: Software tungsten light correction"
In response to Reply # 3


Cary, US
          

That's certainly one way of going about it! I guess I was more wondering if Photoshop documented anywhere (in the book or in the code) what function they applied to each bit with the various filters it can apply.

- David Schmidt

  

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Mikepoison Basic MemberWed 22-Nov-00 08:39 PM
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#5. "RE: Software tungsten light correction"
In response to Reply # 4


Amsterdam, NL
          

The term 'filter' in photoshop is the general name for 'effect' in most other packages. Photoshop conciders everything, from color changers to full blown fire-rendering plugins, to be a 'filter'.

It has no real preset filters that are analogous to the photographic world of filtering, but with the Hue/Saturation, Color-Balance, and brightness/contrast dialogs, you can achieve pretty much the same effect on many images.

If that's not enough, the 'filter factory' allows you to take it one step further and apply (small) color algorithms based on the current R,G,B and A values to any of those four values, to come up with (sometimes sick, sometimes nice) results.

there is no collection of Photopgrahics filters available though.. and until I get this Photoshop SDK figured out, so I can write some advanced algorithms for color filtering in C++, someone will either have to beat me to it by starting on working out the SDK too, or there just aren't any prefab ones around =)

Mike K.

"The world will not be quantified on celluloid... But I'll be damned if I don't try!"

  

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