How to Color Correct RGB Images Easily in Photoshop

MichaelM 27-07-2009

How to Color Correct RGB Images Easily in Photoshop 1I’m back again to bring you the next trick in my arsenal of Photoshop goodies. The subject today is color correction. Specifically RGB color correction, for web and screen (monitor, tv, little camera screen, iPhone) use.


There are 2 major, accepted color scales out there for consumption by human eyes – additive color and subtractive color. Subtractive color is accomplished via some sort of dyeing, screening or printing How To Print A Web Page The Way You Want It Read More method. This is achieved by mixing either custom ink colors, or adopting a color scale , which in the subtractive realm of color, is called CMYK.

This refers to the 4 base colors used to physically, in paint or dye form, mix together to allow the formation of any color in the Cyan Magenta Yellow Black scale. This is what’s knows as CMYK – but i’m not sure why K stands for black though.

Additive color is the realm of discussion in this article. Additive color refers to the scale of color produced by adding different colors of light (rather than ink) to produce an image or color shade. In additive color, when you add the 3 primary colors together, Red Green and Blue (RGB), you get pure white, as illustrated in the additive color wheel The Ultimate, Free Online Color Schemer To Help Complement Your Colors Read More above. Whereas if you mix together Cyan, Magenta, Yellow, and Black inks, you get a dull brown.

Since RGB is the primary color scale for all monitors, phones, screens, laptops, anything that produces light; we will be discussing this today, as a way to empower you to be able to have brilliant images on your websites, and to get the most out of the pictures you snap in with your camera in any condition. We begin with a picture of a clearing on the ocean.


The following picture looks dull, discolored and too red. But you’d be surprised how much color information is contained in the picture, that simply needs to be brought out.

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Open the image in Photoshop and you can follow along as you read the article. The tool we will be using can be found in the Image menu under Adjustments, and it’s called Levels. Otherwise it can be Hotkeyed at Ctrl-L.

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The levels panel is one of the most used panels in Photoshop. You will also find Auto Levels. It is not recommended to use Auto Levels because it simply cannot replace the eye, and most importantly the taste of the viewer.

Once you have the levels panel open, there is a simple way to tell if all of the available color information is being used. The following is the levels output from the original image of the clearing on the water, showing a red discrepancy where all of the available color frequencies aren’t being utilized to their potential:

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In order to correct this, and the inherent lack of color and brightness in the image, we need to give each respective primary color its own attention.


Using the Channel picker at the top we first choose the Red channel.  Next, pull the right, white slider over to the left where the dots begin to appear on the graph, indicating the channels are being used. Next pull the left, black slider over to the right to the point where the channel begins to show usage. Do this for red, green, and blue respectively.

As you make these changes, make sure the Preview checkbox is ticked so you can see your changes in action. Here’s what the process looks like, after gradually fixing red, green and blue:

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Notice that even when we only fix the red channel, the picture already gets slightly brighter and richer. By bringing these sliders in, we are essentially telling Photoshop to spread the available color information over a wider range of color frequencies, and thus fill out the full spectrum more richly. Next we move on to the green channel.


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At this juncture shown above, the picture starts to become richer and more saturated with color.

After finally adjusting the blue channel below, we can see the picture is at a very rich stage. Details that weren’t previously visible shine out now. What used to be shadows in the bushes are now more bushes, more leaves, more detail. And you would have never known the image contains all this information if you didn’t open the Levels panel.

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Using these steps, you can take any RGB image and really pull the most out of the information that’s there.

Not all the detail in a picture is immediately visible to the naked eye. But with the Photoshop Levels tool you can maximize on detail and quality for each image.

Explore more about: Adobe Photoshop, Image Editor.

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  1. rahiz
    July 30, 2009 at 2:04 am

    Thanks for the tutorial..and yh photoshop is the best software available and i have it :)

  2. Jersey Bob
    July 28, 2009 at 9:45 pm

    While this article did a good job of explaining the Levels command, using it this way is destructive -- if you don't remember to make a copy of your file, you can ruin it. It's better to apply Levels as adjustment layers. Not only is that non-destructive, but you can experiment with different settings, and hide or show adjustment layers at will until you get the best results. Photoshop CS4 makes levels easier than earlier versions, since they are now in a separate panel.

    • Jersey Bob
      July 28, 2009 at 9:52 pm

      Oops -- that should have read "Photoshop CS4 makes adjustment layers easier..."

    • MichaelM
      July 29, 2009 at 8:51 am

      I appreciate the input Jersey Bob. I'm not currently using CS4, but rather plain, old CS. I know this is contradictory to what every designer says about staying up to date, but it serves me well. I am aware of the adjustment layers in CS4 and I have used them. But adjustment layers in and of themselves sound like a GREAT topic for my next article (once I get my CS4 upgrade). In short, adjustment layers warrant their own article, which is why i didn't approach them in this article.
      If anyone reading this article is using any version of Photoshop that has adjustment layers, I strongly suggest using them for the same reason Jersey Bob mentioned above. For the rest of us on older versions, SAVE EARLY SAVE OFTEN.

  3. MichaelM
    July 28, 2009 at 9:37 am

    The above article shows people how to makeUseOf Photoshop to do what you have to do. We have featured other free applications that do Photoshop-like stuff but nothing compares to PhotoShop. It's industry standard for a reason.

    How many of you out there DON'T want to see Photoshop tutorials?

  4. Jim Posniewski
    July 28, 2009 at 8:30 am

    In the interest of the makeuseof policy of 'free' applications:
    Why don't you describe the process for a free program rather than the most expensive graphics editing program?

    • Mark O'Neill
      July 28, 2009 at 10:58 am

      We tend to make a bit of an exception with PhotoShop because it is so widely used and installed on so many computers. So we figure a great number of people will still benefit from such articles.

      As Michael says, we have, in the past, featured posts on free applications that try to do pretty much the same thing such as GIMP.