Digital Editing 101 – Managing Light Temperature

temp.jpgThose of you who’ve been following my beginner’s photography posts from the start will remember that this was actually the first post of the point-and-shoot series many many months ago.

In that post, I explained that all light has a colour tint (referred to as ‘temperature) and I also covered the basics of how to manage the white balance of your photos. However, what happens you’ve done your best to manage your white balance (or forgotten all about it…as can happen!) but the image has still turned out with an alien blue hue or glaring orange cast?

Well, that’s what post-production is for :)

I need to reiterate here that Photoshopping (which appears to have become a generic term for digitial photo manipulation) is not magic – its not going to be able to take a burned out orange flash image and make it into something with the richness of colour of a daylight shot – its more possible for those who shoot in RAW format, but if you’re using a point-and-shoot and stuck with JPEG compression, I’m afraid that its gonna be a touch more difficult. However, that’s not to say that we can’t vastly improve things!

In the first installment, you received a brief introduction to both the levels and curves adjustment panels, though we used them only to manage the luminosity/light levels in the images. Today, I’ll take you a bit further into each of these tools in order to show you more of how they can help to correct an image!

(Photoshop users have a third tool at their disposal called photo filter, but since I don’t know if that’s one that GIMP has, I won’t cover it unless anyone says they’d like me to add a section on that too!)

temperaturecopy.jpg

Above you can see a rather extreme case of unmanaged white balance. I took this picture rather late in the afternoon before sunset, when the light has quite a blue tint to it, and in my impatience I didn’t set my white balance before taking my shots.

The result? Every single image that I took had this ridiculous blue tint through them.

Mmmm, blue chili. Looks tasty, huh?

Thankfully, I knew how to use my image editor to take it from the awful blue-cast image on the left into the much lovelier balanced image on the right, and I’ll take you through two methods of how you too can fix this all to common mistake!

METHOD 1: LEVELS TOOL

temp1.jpg

While this tool is far from perfect, if you’re lucky then it’ll be the only thing you need to do.

The eyedroppers underneath the buttons to the right of the levels tool work in a similar way to the three arrows under the histogram (the large jagged graph), the eyedropper with black is meant to pick up what the black in the photo appears like, the white eyedropper (to the far right) is meant to be used to pick up what white looks like in your image, and the middle eyedropper, which I’ve circled, is meant to pick up grey.

That’s it. It’s as simple as that. So long as your photo has a neutral colour spot (a neutral grey) in the image somewhere, all you have to do is click on the middle eyedropper, then click on they grey spot and you’re good!

The grey can be anything, perhaps a piece of cutlery or even a shadow, so long as its neutral in colour then it will provide the fix that you want. Just try clicking around a few times to find a spot that will correct the colour as much as possible.

However, if there is no neutral grey in your image, then I’m afraid you’ll need to do a bit more work…

temperature1.jpg

As you can see here, despite my clicking around the image, I have not managed to find a neutral grey spot to completely correct my colours (not even the bowl, which is actually a very pale sky blue). I have managed to correct some of the colour cast, but more work needs to be done.

If, like in this image, you haven’t been able to completely correct the colour cast, then you can try the next step, which involves the curves tool!.

METHOD 2: CURVES TOOL

temperature2.jpg In the first installment of this series, I showed you the very basics of utilizing this tool, and today we go a bit further into it. In the image to the left, you can see that I’ve circled the pull down menu under ‘channel’, this is the aspect of this tool that we’ll be managing in this lesson.

The channel menu has four options:

1. RGB - this manages all three colours at once, therefore manages overall luminosity of an image.

2. Red – This manages all the red tones in the image

3. Green - This manages all the green tones in the image

4. Blue – This manages all the blue tones in the image

Pretty straight forward, right?

Well, hopefully you’ll played around a bit with the curves tool since our last lesson and have accustomed yourself with how to alter the points in order to boost/reduce highlights and lowlights, as the colour channels work in exactly the same way.

Working your way through each of the channels one at a time, slowly altering the curve of each tone, placing as many markers as you need and bearing in mind that the colours affect both the shadows, highlights and midpoints (that’s a hint that you should use at least three markers). Don’t be afraid to go back to a channel after you’ve altered another one, it can take a bit of fiddling to come to a point where the image finally has gotten rid of its colour cast, like so:

tempwhite1a2.jpg

Can you see how the blue colour cast has been gotten rid of? I’ve also edited the exposure to bring the luminosity of the image to levels that I am happy with. However, the down side of that is that the colours of the chili have become quite bland and orangey, with little difference between the kidney bean or capsicum. For that, you’ll have to come back next week for the lesson on how to correct colour, when I’ll cover:

  • Colour balance
  • Hue/Saturation

Which, used in conjunction with the curves and levels tools (can you see yet that these two are vital to great photo editing), can give you a final image like this:

tempwhite1b.jpg

The left is just the white balance edited image, the right is what it looks like once we’ve corrected for colour. You may think that the difference is subtle, but learning these techniques can take an average photo and create something marvellous!

[tags]light, exposure, editing, photoshop, photo manipulation, software, photography, white balance[/tags]

Comments

  1. Hi Ellie,
    Love your pictures! What photo-editing program do you use?
    Cathy recently posted..Make your own Greek yogurt

  2. Okay, I read the next post in the series and realized you use photoshop :) Can you use these functions in free programs like Gimp? I’m just starting to use photo editing and I’m not very familiar yet..
    Cathy recently posted..Make your own Greek yogurt

    • As far as I’m aware, GIMP offers everything that Photoshop does so you should be able to edit levels etc :) Unfortunately, I’ve never used it so I couldn’t tell you where these are located in the menus :(

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