Increality

Tutorial Information:
Basic color correction methods for optimizing an image.
Photoshop Version CS2 used (works for many versions).
Goes over general work flow, inluding optimizing for exposure, contrast and color correction.
Non destructive image optimization
You should acquire some knowledge of Photoshop’s interface before using this tutorial. All images in this tutorial can be clicked on to enlarge for better visibility.

I call this tutorial Basic Color Correction although the name is a tad missleading. This tutorial is actually a little more advanced than the basic way some have gone about optimizing their images. If you have been one of those people optimizing your images by going to Image> Adjustment> Auto Levels and Image> Adjustment> Auto Curves, then you’ve been going about it the very basic way. This tutorial will show you how to properly optimize your images for exposure, contrast and color the RIGHT way. I promise you once you’ve learned these techniques you’ll never want to go back to that basic “non controlled” and destructive method. So without any further ado, lets begin!
Step 1. (Exposure) You can begin this tutorial by downloading the following image provided here. This tutorial will work for almost any image, but for follow along reasons it’s best that we’re working on the same image for this tut. Going to your layers palette on the right, at the bottom your going to want to click on the half circle icon to create a new adjustment layer. Then click the “Levels” option. See the image to the right here for an example of this. ——–Tip——– There is another way to reach this new adjustment layer option. On the top of Photoshop in the menus select the “Layer” option and go to “New Adjustment Layer” and choose levels from in there. Or any adjustment for that matter. This gives you an added option to create the adjustment for “Previous Layer” only in the dialog box that pops up. Very handy! ——-End Tip——— {mosimage}
Ok, after clicking on levels you will get a Levels dialog box that appears that contains a few options and a black mountain looking thing known as a histogram. This histogram is very important because it shows you the exposure of your image. Take a look at the image to the right here. The histogram has three sliders (they look like triangles right below the histogram) and I’ve labeled them A, B, and C in blue. A. this first one is your darks. B. this second one, in the middle, is your mid tones, or middle gray. C. last one is your lights. As you can see with the histogram, there are some flat areas. Areas where there is no black, or the black is completly flat. That means there is no tonal values in your image in those areas. Making sure you Preview button is checked on the bottom right in this dialog, click and drag the left slider (A) to the right until it just barely touches the tip of the mountain slope. Now, with the right slider (C), click and drag to the left until it just reaches the slope of the mountain. Check this second image here to see how I’ve adjusted my sliders. Great! Click ok and we can move on to the next page for our contrast adjustment. {mosimage} {mosimage}
{mospagebreak_scroll} Step 2. (Color) Ok, now that we have made a levels adjustment layer for the exposure of the image, we need to adjust for the contrast, which will also help with our color correction. We will be using a curves adjustment layer to do this, but before we do we’re going to prep for it by using a threshold adjustment as our guide. You’ll see what I mean here in a second. First make sure that your info pallette is up (main menu, click Window >then Info ). Then go back into the layers pallette and click the half circle icon again. This time, towards the bottom, select “Threshold”. This will open a new dialog box for your threshold and if you notice your image will turn into a vector looking black & white version of your image. This is ok. This time you are given only one slider which starts out in the very middle. Check the image here to the right to see a preview of this dialog box and the image in the background. {mosimage}
Drag the slider all the way to the left. You’ll notice your image goes almost completly white. Now very slowly drag the slider back towards the center and you’ll see some of your darks re-appear. Once you have a small amount of your darks back in visibility, scroll your mouse over to that area of the image and you’ll notice the mouse icon is in the shape of the color drop picker icon. Putting the color picker over the black, you’ll see in your Info your R, G, and B read-outs. The closer you get the number to 0 on the left of the slash for each of the RG & B the closer you will be to black. Once you find that area, while holding down the Shift key, left click it and it will place a marker for you. Don’t close the threshold dialog! Now, drag the slider all the way to the right. You see now it’s gone to the opposite effect and made everything black. Slowly drag it back to the center and you’ll be able to see where your first amounts of white begin to show up. Now, using that as a guide, and using your info pallette read-out, find the closest thing you can to white. This time instead of zero you’ll be looking for an RGB that is close to 255. Shift click again your mouse to make a marker for your white point. Now hit Cancel on the Threshold dialog box. Yes, hit cancel! If you accidently hit ok on the threshold adjustment layer, just delete it out of the layers pallette, we only needed it to place our black and white markers.
Ok we’re set and can now begin with our curves (contrast) adjustment. Go back to your layer pallette and click the half circle icon again, and this time select “Curves” as your new layer adjustment. The curves dialog box will appear and show a graph looking thing in the middle of it. This curves adjustment dialog box is one of the most powerful image optimization features in Photoshop so its very wise to learn about it. Now, with the image to the right here, I’ve marked in blue font where your eye droppers are for the black and white point. As you can see, my mouse is hovered over the black one and it even says “Set Black Point” for me. Since ealier we set the location where we wanted to set our white and black points using threshold, we’ll see the two markers now on the image. Now they’re super easy to find! Click the “Set Black Point” eye dropper tool there in the Curves adjustment and scroll over to the first maker (says a number 1 by it). It will be the one over a dark area of the image, since we’re setting for black. Now go ahead and click. Next, go back to the curves dialog and select the “Set White Point” eye dropper tool. Do the same thing here as before but select the second marker and click it on your image to set the white point. You won’t see a major difference here with this image (if you do see a huge difference and it’s bad, hit ctrl z to step backwards) but this can be huge for other images. Now you can either leave this dialog box open for the next step, or hit the Ok button and then create a new adjustment layer for curves on top of the first curves to continue. {mosimage}
{mospagebreak_scroll} Step 3. (Contrast & Color) Now continuing onwards, we’re coming to the last area of this optimization. In preperation of this, expand your curves dialog box open to it’s largest size at the bottom right if it isn’t already. Also, “Alt” click onto the graph area anywhere you like and you’ll notice it changes the graph to larger or smaller. Stick with the more complex small one. You may also notice once you click the “Alt” key while in this dialog box that the Cancel button turns into a Reset button. This is useful if you make a mistake. Ok, left click right in the very center of the graph on the diagonal line going across it. You’ll know your in the center because your Input and Output readings below will be 127 and 127. After clicking that, make another two points, one half way up from the center towards the top, and one half way down towards the bottom. You can then pull them to any direction you want and you’ll notice your image changes (make sure preview is on). Take a look at the reference image provided here to the right to see how I adjusted mine. You almost always go for an S curve when doing this. You can also add more points if you like and adjust more. What your looking for is an addition to the contrast of your image, something to pop it out a little more. This at the same time will adjust your color slightly. Remember that only a slight adjustment is needed for most photographs. More complex things can be done using this curves adjustment layer to manipulate the outcome of your image. {mosimage}
Step 4. (Non distructive image optimization) So what does it all mean you may ask. How is this a better workflow rather than just going to Image > Adjustment > Auto Levels & Curves? What you have done with this setup is made a set of adjustment layers on top of your original layer that all can be deleted or altered. This is an extremely powerful way to work with photoshop. By using the auto adjust features, what your doing is letting photoshop optimize your image by guessing, and destroying the original because if you save it after the auto adjust you can’t go back. Take a look at the layer pallette image to the right here. You can see that I have 3 adjustment layers, and I have the power to delete them, re-adjust them, or even change the opacity for them. Try it, go over to the half circle on your top layer, not at the bottom of the layers pallette this time, but click on the half circle on the actual layer. You’ll see that layer’s curve adjustment will re-open and you can make more adjustments. That’s not the end my friend! If you haven’t already noticed, every adjustment layer is made and comes packaged and shipped directly to you with it’s own layer mask! Which means even more control. (the layer mask is the white box in each of the adjustment layers). If you know anything about masks, you’ll see how useful this can be. So that’s it. We’ve made a great improvement to this image. I hope you found this tutorial useful and I’ve changed your mind about old color optimization techniques. Please check out more of my tutorials in photoshop, including the Magic Big E Trick as an extension of this tutorial. Thanks! {mosimage}

This tutorial is © 2007 Increality.com
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