Change a Background in Photoshop (Clean, Realistic Results)
You’ll replace a background, cut out the subject cleanly, and make the composite look realistic. We’ll use Select and Mask for the cutout, align light direction and perspective, extend the backdrop if needed, blur for depth of field, and color-match the subject and scene. Finish with a global color grade and final mask clean-up.
Step-by-step instructions
Place the new background
Go to File → Place Embedded, select your background image, and click Place.
Shift-drag a corner handle to scale it to fill the canvas.
Press Enter/Return or click the checkmark to confirm.
Organize your layers
Unlock the original photo layer by clicking the lock icon; rename it (e.g., Runner).
Drag the Runner layer above the background in the Layers panel.
Select the subject with Select and Mask
With Runner selected, go to Select → Select and Mask.
Set View to Onion Skin and Transparency to about 50%.
Click Select Subject to auto-select the person.
Refine global mask edges
Switch View to Black & White to inspect edges clearly.
Increase Smooth to reduce jagged edges and raise Contrast to sharpen them.
Set Output To → Layer Mask, then click OK.
Improve hair selection
Double-click the layer mask to reopen Select and Mask.
Choose the Refine Edge tool and click Refine Hair (or paint manually along hair).
Click OK, then use the Brush Tool on the mask (white reveals, black conceals) to fix missed areas.
Match light direction
Select the background layer and press Ctrl+T (Cmd+T on Mac).
Right-click inside the transform box and choose Flip Horizontal.
Press Enter/Return to apply.
Align perspective and horizon
Press Ctrl+R (Cmd+R) to show rulers; drag a guide to the estimated horizon line.
Move/scale the background so its horizon aligns with the guide.
Fill any empty canvas areas
If the background is a Smart Object, right-click it and choose Rasterize Layer.
Use the Rectangular Marquee Tool to select transparent sky at the top.
Go to Edit → Content-Aware Fill, set Output To → Current Layer, and click OK.
Add realistic depth of field to the background
Right-click the background and choose Convert to Smart Object.
Go to Filter → Blur Gallery → Tilt-Shift.
Place the solid focus line near the subject’s feet, set Blur to about 14 px, adjust the dashed line for a gentle transition, and click OK.
Fine-tune later by double-clicking the blur effect (it’s non-destructive).
Color-match the subject
Go to Layer → New Adjustment Layer → Levels, then click the clipping mask icon to affect only the Runner layer.
Adjust midtones/highlights for brightness match.
Switch channels: add a little Red; in Blue channel add Yellow (move left) to warm if needed.
Apply a global color grade
Go to Layer → New Adjustment Layer → Color Lookup.
Choose a 3D LUT that fits the mood, then lower Opacity if it’s too strong.
Finish with mask clean-up
Select the Runner’s layer mask.
Paint with black to hide spill (e.g., between fingers) and with white to restore lost details.
Save your work (File → Save).
