Stretch an Image in Photoshop with Content-Aware Scale
When you need to extend a background or terrain without distorting your subject, Content-Aware Scale can intelligently stretch pixels. Start by isolating the area to stretch using rectangular selections to keep rows or columns intact. Then scale with Content-Aware and blend any seams for a natural result.

Step-by-step instructions
Select the area to stretch
Choose the Rectangular Marquee Tool (M).
Drag a selection that covers only the region you want stretched (for example, the rocks), avoiding important subjects or background elements.
Hold Alt/Option and drag a rectangle to subtract protected areas (e.g., a person’s legs) from the selection.
Copy the selection to a new layer
Press Ctrl+Alt+J (Windows) or Command+Option+J (Mac) to New Layer via Copy.
Name the layer “stretch” and click OK.
Enable Overscroll for easier panning (if needed)
Open preferences: Edit → Preferences → Tools (Windows) or Photoshop → Preferences → Tools (Mac).
Turn on Overscroll, then click OK.
Scroll or zoom so you can see and drag the bottom transform handle comfortably.
Scale with Content-Aware Scale
Go to Edit → Content-Aware Scale.
Shift-drag the bottom middle handle downward until the Height is approximately 150% (Width should stay near 100%).
Lower the Amount slider to reduce warping; around 12% gave a natural result in the example (0% behaves like Free Transform; higher values increase the AI’s warping).
Press Enter/Return to apply.
Blend seams with the Spot Healing Brush
Select the Spot Healing Brush Tool (J).
In the Options bar, enable Sample All Layers.
Use ] to increase brush size and paint along any visible seams where stretched and unstretched areas meet.
Aim for a natural overlap (e.g., smaller rocks overlapping onto larger ones) and retouch both sides as needed.