Smart cutout handles most images, but hair strands and transparent objects still need manual work. This walkthrough covers the whole path from Select Subject to edge refinement, and it stays focused on the parts that actually fight back — plus what to do when the result still looks wrong.
Duplicate the background layer. Same as always: Ctrl+J. Build the habit now, or you'll have nowhere to retreat to when the cutout goes bad.
Grab the subject quickly. Find the Quick Selection tool in the toolbar on the left — the brush with the dashed ring around it. Paint over your subject. Drop the brush size if you want more precision. Hold Alt to subtract from the selection. On newer versions you can just hit Select Subject and get it in one click, but automatic selection isn't always perfect, so it's worth tidying up with Quick Selection.
Quick Selection tends to spill over when you first start using it. Don't rush it — just subtract a little more often.
Open Select and Mask. Once the selection looks roughly right, click Select and Mask… in the top menu. This is the step that decides everything.
Refine the edge. Pick the Refine Edge Brush tool in the left toolbar — second row, the one with the brush icon. Paint along the hair and any messy edges and Photoshop works out the boundary for you. The panel on the right lets you tune Edge Detection, Smart Radius and so on. For the view mode I'd pick Overlay or Black & White, because then you can actually see what's been cleaned up and what hasn't.
Small trick here: if the subject's edge is carrying the old background color, tick Decontaminate Colors under Output Settings and the fringe goes away.
Output to a new layer with a mask. Under Output Settings choose New Layer with Layer Mask, then click OK. You end up with an extra masked layer, and the original image is still there.
Bring in the new background. Drag your new background image into the document and move it below the masked layer. Position and scale it however you like. That's it.
A few extras:
- If the cutout comes out with a white fringe, load the mask as a selection by Ctrl-clicking the mask thumbnail, then go Select>Modify>Contract by 1-2 pixels, invert the selection and delete. The fringe is gone.
- Or just pull the Shift Edge slider slightly into negative territory inside Select and Mask.
- If your background is a fairly plain color you can also select it with Color Range and delete it, but the smart cutout route is less work.
That's basically the whole thing. I've run this workflow many times and it lands more often than not. Truly difficult images still need channels or the Pen tool on top, but for everyday retouching this is plenty.
If installing Photoshop feels like too much hassle, or you only need it once in a while, try the online PS I mentioned above at https://www.zaixianps.cc. Nothing to install, and it has a similar smart cutout built in. At the very least it'll get you out of a jam.