As most of us know, our cameras do not always reproduce the scene we are capturing as we experience it. Regardless of how sophisticated or expensive our tools, often we have color casts or lack of contrast. Often, we are actually responsible for the adding the color casts, for example if we use graduated Neutral Density Filters – only the most expensive are truly neutral, the rest tend to add a magenta color cast. Other examples are Blue/Gold Polarizers, or Big Stopper 10 stop ND filters.
Natural Color Casts happen in twilight, sunrise and sunset or at night, when in camera white balance can get thrown off quite badly, especially in mixed lighting conditions.
Of course, some of these color casts at sunrise or sunset make our images look fantastic, the brilliant warm colors are so appealing, but are they authentic?
In this example, I want to show a couple of methods of color correcting images and you can judge for yourselves which is more useful for your workflow.
The original image was taken in very warm light on the coast of Asturias in Spain. The multi-colored banded rocks make an interesting subject, but the camera recorded a very warm white balance.
When looking at the image in Lightroom 3 using the Develop Screen, the details of the White Balance slider reveal essentially a Daylight setting of 5750K.
The fastest and often excellent way to correcta color cast is to use the eye-dropper tool in the White Balance area. When you hover the tool over the image a highly localised view shows the actual pixels underneath the point, and you can select a pixel accurately that you believe should be a neautral grey.
By doing this, it resulted in the next image.
And, in all honesty its done a great job of neutralising that color cast. But, has it gone too far, has it stripped the image of that warm feel of late evening light? But, for a one-click fix, its excellent.
It has cooled down the temperature to 3900K, as shown here.
But, it has only addressed color and not contrast.
The rest of this article focusses on using Photoshop CS5 to make more detailed changes.
Opening the original in Photoshop CS5 as a 16bit Tiff, the first thing to do is to add a Threshold Layer. This is a specialised layer designed specifically to set Black and White Points for your image, and works like this.
At the bottom of your layers palette there is a black and white circle, click on this and it gives a drop down menu of layers that can be added to your background layer. Choose Threshold.
The first thing that happens is your images changes from the normal RGB view into some crazy black and white abstract, but it also adds a new element to your screen, a histogram above the layers group with a slider underneath it.
The next bit is the tricky bit.
1: Move the white slider left and you will see the black areas in your image disappear. Keep going left until only a tiny area of black remains. Zoom in using your magnifying tool, or use CMD + to zoom in (on a Mac).
2: Use the eye dropper tool and hold down SHIFT, while you click on one of the Black Pixels. This sets your Black Point.
3: Zoom out again, and move the Threshold Slider all the way to the right until the same thing happens. The image shows all black until a very few White Pixels remain. Clicking on one of these sets the White Point.
In the Information Palette, two new points arrive giving RGB values for the Black Point 1, and the White Point 2. As shown below.
In this example, it is seen that the Black Point is already very Black, with an RBG value of 2,1,0
If you intend to print your images, it can be good practice to aim for a 5,5,5 Black Point, which means you have some shadow details.
The White point here is the most value to us, as 223,217,180 clearly shows that we can aim to create better color and contrast by adjusting the whites in the Image,
The Threshold layer has now done its job and you can simply select it and delete it by clicking the trash can in the lower right of the layers palette, or drag the layer into the trash can.
Next, ADD a Curves layer as shown below.
We will use the Red, Green and Blue channels in the Curves Layer to adjust our white point.
Where it says RGB above the curve, open the drop down and select RED.
Use the white slider on the right under the Histogram and move it left. Watch the figures in the Info Palette, and aim to get the R value of the RGB color to 252. It may not get there, you might have to settle for 251 0r 253. This of course makes the image very Red!
Next, repeat this process with the Green Channel.
Not looking so good, but we’re not done yet!
Finally, repeat the process with the Blue Channel.
Now, if we examine the RGB Histogram in the Curves Palette, we see te original Black line, overlaid with three colored lines showing the Red, Green and Blue Curves.
The final color corrected image is shown below.
Comparing this with the Original and the Lighroom Corrected image, it is clearly different again, but to my eyes retains a lot of the warmth of the original scene, but with a more neutral color. It has also increased the GLOBAL CONTRAST, as we moved all three areas of highlights to the left.
There is not really a right or wrong here, processing is a vital and important part of our complete workflow, from the moment we experience an event, through the capture stage and finally, through processing, we get a representation of that event that we can share with others.
Every scene is different and every image is unique. The Threshold Layer is just another tool in the box of tricks that we can utilise to help us on the path to more expressive images.