Photoshop Crash Course: Manipulating a color

Sometimes we need to edit a certain color within a photograph for any number of reasons (it’s the perfect photo, if only the hat were green instead of red!  Or, if only the carrots in this photo were the only thing in color!  Or, this picture is remembering it wrong, I thought the boat was more colorful).

For an example of how you can take care of these problems in Photoshop, let’s try out changing the color of the flowers in this photo (click through to see the original in the Wikimedia commons).  Let’s see if we can  change the flower color to yellow.

A_Nice_Red_Flowers

First, we’re going to need to isolate the flowers so that we can change their color.  Selecting around all those shapes would be pretty tedious and probably not turn out very well if we used the pen tool or the lasso select.

Instead, since we’re aiming to change all of the vibrant red parts of the image to yellow, let’s use something called select by color range (which, oddly enough, selects everything in an image within a range you can select on the spectrum of colors).  To find this tool, go to the select menu and then click color range.

Of course, in order to get it to select the color we want and nothing else, we’re going to have to give the tool some more information.  Click on the flower in the picture, and it will start by selecting things with a very similar color to that color red.  To make sure we get all of the petals instead of just the ones that are the exact shade of the one we clicked on, let’s turn up the fuzziness (how faithful it is to the edges) and the range (the spectrum of colors it will include).

Since we’re also trying to select specific objects, let’s check the boxes for detect faces, which helps it find the geometry of the flower petals, and localized color clusters, which tells it to be more generous with clusters of the color all together, since the petals are close by.  Here is the color range options box with these settings:

Screen Shot 2014-01-10 at 2.25.57 PM

With these se, we get something like this:

Step 1: Select>Color Range  settings: detect faces checked, localized color clusters checked, fuzziness up, range up

Screen Shot 2014-01-10 at 9.54.56 AM

Notice that not every single red (or reddish pink) area seems to be selected.  The color select area is a little tricky-it selects using an alpha channel, meaning that it will have a stronger effect on areas closer to our original target color.  This means that even though some of the petals aren’t fully selected, they will be somewhat effected by changes we make.  This will help us to keep more color variation, like the variety between red reds and pink reds in the original picture.

Let’s go ahead and change that color to yellow.  Go to the Image menu, select Adjustments, and then select Hue/Saturation.  Now you can move the slider bar over to yellow and bump up the saturation a little too.  You should get something like this:

Step 2: Image>Adjustments>Hue/Saturation adjust hue and saturation sliders to the right

Screen Shot 2014-01-10 at 10.00.08 AM

Great!  Yellow flowers, just like we always wanted!  Maybe for added fun, you want the flowers to be the only bright color in the picture so that it can better remind you of the pictures hanging on the wall of your dentist’s office.  Let’s turn that saturation down (along with the saturation of everything else in the picture), so that our flowers are the only thing in a bright color.  To select the opposite of what you had picked before, go to the Select menu and choose Inverse.  Now, you can go back to Image, Adjustments, Hue/Saturation, and this time, turn the saturation way down.

Step 3: Select>Inverse then Image>Adjustments>Hue/Saturation, turn saturation down

Screen Shot 2014-01-10 at 10.04.39 AM

And there it is.  Our flowers are yellow and nothing else has much color anymore, all thanks to the color range tool.  Go forth and use it judicially.  Or just make lots of cheesy self-portraits where only your eyes are in color.  Whatever floats your now-much-brighter boat!

If you would like to learn more about selection techniques in Photoshop, including how they work and when they might be useful, be sure to sign up for the Photoshop Selection Tools workshop I’ll be teaching in the Weigle Information Commons on February 13th.

For more about how WIC can help you learn more about Photoshop, check out WIC’s Photoshop Guide.

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