Here is a 2 minute color correction technique I picked up from one of Scott Kelby’s books. Its fairly simple, and it ranks as beginner-advanced.
Here is the basic image before color correction. You can save this image and follow along if you want.
In your layer palette, click the adjustment layer icon, and choose threshold. This will put a threshold layer above your glass layer, this is how you will choose the darkest and lightest parts of the image for color correcting using curves.
This is the threshold adjustment tool. You want to move the slider all the way to the left, then little by little move it right until you see it start to pick up a pixel or two. The little black bar, is the darkest part of the photo.
Zoom way into your pixel that is black, and choose your color sample tool. Make sure it is set to “point sample” and click once on the black pixel. It will put a marker with a number 1 on it. You have now marked your darkest part in your image.
Okay, time for the white point. Double click the threshold layer to bring the threshold dialogue box back up. Now slide it all the way to the right, with this particular image, it has been “blown out” so to speak, so there are lots of white pixels to choose from, normally you would creep it back in to the left until the white pixels showed up. Do the same thing we did with the black pixels. Choose your color sample eyedrop tool and click a marker on one of the white pixels. This should be marker number 2 now, your brightest pixel.
Now that we have our markers selected, lets delete the threshold layer by throwing it in the trash can in the layers palette. Zoom way in to your marker one. Go to image>adjustments>curves. Click on the black eyedropper in the curves dialogue box, and click it right on top of marker number 1. You will see that your image just changed to a darker hue. Close the curves dialogue box.
Now zoom out until you can see your marker number 2, zoom all the way into that, and bring your curves dialogue box back up. Image>adjustments>curves. Now select the white eyedropper tool, and click directly on your marker number 2. This will set the white point in your image. Close the curves dialogue box.
So now you have your image somewhat there, but there is another step. Since most digital cameras tend to put in either magenta or cyan hues into every photograph, you are going to want to set a midtone curve adjustment. This is the toughest part about color correcting, and will take some learning with every image, but it basically goes like this. You want to find a gray pixel somewhere in your image. Luckily on this image in particular, the background is a nice gray tone so we will use that. Zoom all the way in to the background, I used the background of the glass piece on the left. Now bring your curves dialogue box back up, and click on the middle eyedropper tool, which is your midtone selection tool. Click on any gray pixel. This basically just took out magenta and added some more cyan into the image to really bring the glass out.
The image is still kinda washed out, so go to image>adjustments>levels. Now move your left slider in to the right until it hits the base of the lines. And repeat this step for the sliders on the right, moving them into the left until they hit the lines. Also, adjust your middle slider to somewhere in between until it looks right.
This is basically the final result, you can now choose your eyedropper select tool, and at the top hit the “clear” button, this will remove your markers and you are set to go. It takes some getting used to, but this is by far the best way to color correct any image. This is really how the “pro’s” do it. I hope you enjoy!
If you liked this tutorial, please drop me a note and let me know.