Photo Color Correction

Color Correction
by Brad Alexander

For a while now I've been combing the internet for tips and tricks in Photoshop. I've learned quite a bit, but I must confess, in many cases I don't know or understand why something works, I just know it does. Most of what I know now has come from asking others and researching the net on certain topics. There is a lot of free advice out there, one only needs to search. Keep in mind that I'm using Photoshop CS2 and these tips may not work in earlier versions of PS and will not work in other photo editing software. I hope to have other tutorials available here and there but I would encourage others to submit their PS tips to Scott for submission.

This tutorial is dedicated to color correcting. Please be aware that everyone's monitor and video card are very different and what you see may not look like what I and others see. This is especially true with the Personal Computer, but can be corrected with hardware and software calibrators. As much as I hate to admit it, Macs tend have much better and more correct color - sorry PC guys, it is what it is. Of course, that doesn't mean we shouldn't at least try to get it somewhat right for viewing, if not for others, then for ourselves.

***A quick note before you get started - at first this job may seem a bit much, but once you've done it a few times, it takes less than a minute to apply.***

So you have an image that you know the color is off and you need to correct it. There are a few options to fix the problem but I've come to prefer the one that follows.

   Open the image you want to work with in PS - be sure you have your layers window open. The layers window can be opened by going to "window" at the top of PS and clicking on "layers".

   Our goal now is to set some reference points - black, white and neutral gray.

   From the layers window click on the adjustment layer icon (looks like a circle that is filled with half white and half black) and click on "threshold".

Next you are going to see your image turn to a black and white image with the "threshhold" dialogue box open.

As shown below, you will need to slide the threshold slider all the way to the left. This will make the image completely white. Now slowly move the slider to the right until you start to see some of the black portions of the image coming back into view. This is when you will set your black point - as you move your mouse over the image you'll see it turns into an eye dropper. Press the shift button down on your keyboard and click on the black area that first showed up on the screen. Your black point is now set.

Now slide the threshold slider all the way to the right. This will make the image completely black. Slowly slide the slider back to the left until you start to see some of the white show back up (see image below). In the same manner we selected the black point, you are now going to set your white point. Don't forget to press the shift key before clicking on your white point. Now press "cancel" in the threshold dialogue box to get back to your image.

Note: you'll notice that there is a point "1" set for the black and a point "2" set for the white on your image.

Now you want to set your gray, which has a few more steps than the white and black points. At the bottom of your layers dialogue box you'll find an icon for "create new layer" - click on it to create a new blank layer.

From the "edit" drop down menu click on "fill".

The fill dialogue box will now appear. Be sure the "50% gray" is selected and then click "OK".

Your new layer, which is on top of your image is now all gray, but don't let that alarm you, we won't be keeping that layer in the long run.

From the layers menu be sure your new 50% gray layer is selected and then change the blend mode to Difference as shown below.

Once again we are going to click on the adjustment icon (little circle that is half black and half white at the bottom of the layers window). And once again we are going to click on "threshold". Slide the slider all the way to the left then back it off to the right until you again start to see some of the image appear. Here is where you will set your gray point by pressing down the shift key and clicking on the first area that comes back into view (see image below). Once you've made your selection simply cancel out of the threshold dialogue box to return back your image.

You no longer have a need for the 50% gray layer we created so you can delete it. You can do this by grabbing that layer with your mouse and dropping it into the trash can located on the bottom right of the layers window.

Now go back into your adjustment layer and click on "curves".

Your curves dialogue box now appears (see image below). Notice the eye droppers just below the "options" button - the first one from left to right is Black, then Gray and finally White. Select the black eye dropper - hit the "caps lock" key on your keyboard and then select your black point you created earlier on your image (should be point #1) You'll know you are lined up perfectly when the little circle and cross hairs disappear. Do the same thing with each eye dropper corresponding with point 2 and 3 - white and gray (your gray point will be number 3 but the gray eye dropper is in the middle, don't let this confuse you). After doing all three, click the "OK" button on the curves dialogue box and your image is now color corrected. In some cases I like to do this process twice by simply opening up the curves dialogue box from the adjustment layer and repeating (point 1 thru 3 will re-appear when you do this - to toggle these reference points on and off press "crtl and h" on your keyboard).

Now you have at least one adjustment layer on top of your main image layer. You can toggle your adjustment on and off by clicking on the little eye that is just to the left of the adjustment layer. By toggling this off and on you can easily see the changes you've made.

Here is the uncorrected version of the image with lots of yellow.

And here is the corrected version:

Here are a few more examples: Before/After

Additional notes: You'll find that in some cases, setting all three points doesn't work and only setting the neutral gray gives you the best results. As mentioned earlier, you'll also find that duplicating your curves layer by repeating some or all of the steps will give you a cleaner image. My suggestion is to play with various combinations of this correcting process to see what best works for you and for each image. In many images setting the gray dropper in curves does the trick just fine.

FHF thanks Brad Alexander for his contributions!

If you'd like to submit a photography related tip, please email it to FieldHerpForum.com. Submissions must be VERY detailed and image heavy to give a visual aid. Imagery MUST be at or under 800 pixels in width.

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