How to Filter Out a Color with Photoshop
You can filter color in Photoshop on a given image. Many things could be wrong, whether it be the whole image or a portion of it (or a single object in the frame). The balance could be off for a number of reasons, and identifying that reason will help determine the best course of action.
Step 1: Figure out the Overall Problem
Try to figure out whether the whole image is at fault, or just part of it. If it is the whole image, then this will be quite simple. Go to your "Image" drop down and hover over "Adjustments" where you will find "Color Balance." You will be greeted with three slide bars: one goes from Cyan to Red, one from Magenta to Green and one from Blue to Yellow. Identify which color you want to filter out and slide the appropriate bar away from that color. You may need to tweak the other two to compensate for any unfortunate side effects.
Step 2: A Single Object
If you are concerned with only part of it, things could get complicated. Look at the piece that is troubling you and try to determine whether the problem was the light falling on it or the color of the object itself. Perhaps the woman in the background is wearing a sweater which is just too red. Grab your magic wand tool and use it to select the sweater. Holding shift between clicks allows you to grab multiple bits of color that the selector has missed. Now you can go back to step one and make adjustments on just the selected area. Once you are done, deselect the area and you will notice that the mend is not quite seamless. Select your heal tool and use it to smooth over the edges of the area.
Step 3: Secluded Area in Mis-balanced Light
Perhaps the area you are looking at is near a window while the rest of the photo is under indoor light. This is going to require some finesse. Grab your lasso tool. The magic wand will not help you much because it will either select too much or too little. Chances are that the problem area is not consistently unacceptable. Start by lassoing the whole area. Again go back to step 1 and follow the steps outlined there. Be sure to concentrate on the section closest to the edge of the area you are adjusting. Once it is to your liking, deselect the lassoed area and select the now inherently smaller area which is still problematic. Make the adjustment again. Continue grabbing smaller areas in increments until you have the general gradient you want. It will not look smooth, but you can use your heal tool to mend that.
There are many issues that can lead you to filtering out a color from an image. Not all these problems can be fixed, but these steps will get you on your way to mending those that can.
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