Here's how to change the background colors
in Photoshop CC.
Go to "File," "Open," and open your image.
Right-click on the object selection tool
from the toolbar on the left.
Select "Quick Selection Tool."
Click the box for "Sample All Layers"
if you're working with a composite image.
You can also click "Enhance Edge"
for a more precise edge selection.
Click "Select Subject" in the upper toolbar.
For less up-to-date Adobe Photoshop versions,
you'll have to manually outline the subject
in the foreground.
Photoshop has multiple tools,
such as the lasso tool, marquee tool,
and the magic wand tool,
for outlining your subject.
Once you have your area selected,
press the Q key on the keyboard
to enable quick mask mode.
This will help you identify and remedy
any uncaptured pixels.
Zoom in so you can spot the edges and details
that may not have been automatically captured.
Areas that have been captured
as part of the background will be red.
Select the brush tool on the left toolbar.
Paint in pixels as you see fit
to be included or not included in the background.
To include pixels in the background,
paint them black with the brush tool.
They should appear red in quick mask mode.
To remove pixels from the background,
paint them in white with the brush tool,
and they'll be added to the subject.
When you're finished,
zoom out and tap "Q" again
to exit quick mask mode.
Next, select "Solid Color"
from the adjustment layer menu
in the bottom right.
Select any color and click "OK."
Initially, the selected shade will color the subject
rather than the background.
To flip that, select the layer mask icon,
then click "Invert," located in the properties panel.
Double-click on the solid color thumbnail
under the layers tab
and select the color of your choice for the background.