Keep One Color in Photoshop [No Masks Needed!]

Time needed: 3 minutes.

Use the Hue and Saturation Adjustment Layer to desaturate all but one color.

1. Create a Hue and Saturation Adjustment Layer

   From the new Adjustment Layer icon, create a Hue and Saturation Adjustment Layer.

2. Sample a Color

   From the Properties Panel, activate the On-Image Adjustment Tool. Then, click on the color you would like to select.

3. Desaturate The Selected Color

   Drag the Saturation slider all the way to the left to desaturate your selected color. But we want the opposite. We want to keep one color but desaturate the rest. To do so, you will need to invert the selected range of colors.

4. Take Note of The Selected Colors

   From the Properties Panel, look at the color values Photoshop selected. 315º/345º to 15º\45º in this example.

5. Adjust The Sliders on The Right

   Start by dragging to two sliders on 15º\45º the right. Drag from the gray area in between the two sliders to move both sliders at the same time. Once you go past the edge, the slider will appear on the left side.

6. Adjust The Sliders on The Left

   You can then grab the other set of sliders 315º/345º and move them to the appropriate position at 15º\45º.
   
   Then drag the first set of sliders to 315º/345º. This will invert the selected colors, the backpacks will now be in full color and the background desaturated.