The quick answer
Use the Crop tool to set a wider or taller frame. Generative Expand can add a new area around the photo. Keep the important parts inside the frame.
An aspect ratio is the shape of a picture, such as 4:5. It does not tell you how large the file needs to be.
In this article
Keep these in mind
- Set the final shape and size first.
- Leave space where the layout needs it.
- Inspect every new edge before export.
1. Plan the final frame
Find out where the picture will appear. Which part must stay visible? A tall social post needs different space from a wide website banner.
1200 × 1500 pixels and 2400 × 3000 pixels both have a 4:5 shape. The second has more image dots, called pixels. Use the size the website or printer needs.
2. Extend the canvas
Choose the Crop tool. Pull the frame beyond the edge of the photo. Choose Generative Expand from the controls that appear, select an available model, then generate.
Adobe also describes using an empty prompt to continue the scene. If you type an instruction, describe the new area clearly. The buttons may differ with your Photoshop version.
Read more: Use Generative Expand in Photoshop
3. Judge the new area as part of the photo
Look for copied objects, broken lines, bent walls and changes in light. A plain sky needs a different check from a tiled floor.
Look at the whole picture first. Then zoom to 100% to check detail and the join. A tiny preview can hide problems that show up in print.
4. Keep important content
Compare the result with the original. Check that important parts have stayed the same. Keep the original layer wherever exact details matter.
Need the extra space for text? Keep it simple. A busy background can make words hard to read.
5. Check the final crop and export
Check the pixel size after cropping. Save a sample and open it again. Check the shape and leave enough room around important details.
If the new area looks soft at the final size, fix it before delivery. More pixels or a different resolution number will not bring back real detail.
Sources & further reading
Product features can change. Check the linked documentation for the version and service you use.