How to crop an image

Crop an image in six steps

1. 1

   Open the photo

   Choose File› then Open… (Ctrl+O or ⌘O) at lilcactus.app, or drag the photo onto the window. Open the sample from this page to follow along.

2. 2

   Choose the Crop tool

   Right-click the crop-group button on the left toolbar, or press and hold it, and choose Crop. The group also contains Perspective Crop and the slice tools, so choosing the named tool avoids landing on a different one.

   

3. 3

   Choose the shape of the crop

   On the options bar, set Ratio to 1 : 1 for the sample’s square crop. A ratio describes width compared with height, not a number of pixels. A 600 × 600 image and a 1200 × 1200 image both have a 1:1 ratio.

   Keep Delete cropped pixels unticked. Pixels outside the new frame will be hidden, so you can recover them later in the open document or an editable project.

   

4. 4

   Drag and adjust the frame

   Drag diagonally across the photo to draw a square around the tram. The shaded area is what the crop will leave out. Drag a corner or an edge to change the frame’s size, or drag inside it to move the whole frame.

   Keep the tram’s front, roof and wheels inside. Avoid half-cut objects at the edges. The live width × height readout on the options bar shows how many pixels the frame will keep.

   Tip Need to start over? Press Escape to cancel the pending crop and draw another frame.

   

5. 5

   Apply the crop

   Click the checkmark Apply crop on the options bar, or press Enter or ↩. The frame becomes the new canvas and the status bar shows its pixel dimensions. Your numbers may differ from the sample because your drag covered a different area.

   If you want a different composition, Ctrl+Z or ⌘Z undoes the crop so you can draw a new frame.

   

   

6. 6

   Export the cropped copy

   Choose File› then Export› then JPEG… for a photo, or PNG… for a graphic or a transparent image. For an exact 800 × 800 copy, tick Resize output and type 800 in Width. Because you already cropped to a square, Height becomes 800 too. Check the final dimensions at the bottom, then click Export.

   File› then Export always writes a new file. File› then Save writes back into the opened file in its own format: JPEG and PNG stay flat; PSD keeps its supported layers. For an image opened from this page, or any JPEG, the first Save opens the Save Image dialog. File› then Save As› then Lil Cactus Project… keeps layers and hidden areas editable; after that, Save saves the project.

   Tip If the crop contains fewer than 800 pixels on a side, an 800-pixel export enlarges it. Choose a larger crop or a smaller output when you need to preserve detail.

   

   

Crop to a different ratio or an exact size

Choose a preset in Ratio: 1 : 1, 4 : 5, 3 : 2 or 16 : 9. Original keeps the photo’s existing proportions, while Free lets you drag any shape. The swap button beside Ratio switches between portrait and landscape.

For a shape that is not listed, choose Custom and enter its width and height proportions in W and H. For a 1200 × 600 banner, enter 2 and 1, draw and apply the crop, then set the exported width to 1200.

Keep a Free crop inside the photo: dragging outside it can add transparent strips, which JPEG fills with white.

For an exact size in the open document rather than just the copy, crop first and use Image› then Image Size… with the chain link on. Follow how to resize an image.

Straighten a tilted photo before cropping

Download the tilted coast sample and open it with File› then Open… Select Crop, set Ratio to Free and click Straighten on the options bar. Drag a long line along the sloping sea horizon, from left to right. You can also draw along an edge that should be vertical.

When you release the pointer, the image rotates and a crop frame is suggested to remove empty corners. Adjust the frame and apply it. Straightening costs space at the edges, so leave room around your subject when taking the photo.

Escape cancels the suggested frame but leaves the rotation in place. Use Ctrl+Z or ⌘Z to undo the rotation; if you already applied the crop, undo that first, then undo again.

Crop a rectangle photographed at an angle

A poster, page or mosaic photographed from one side looks narrower at the far edge. Perspective Crop stretches that four-sided area into a rectangle. Use it for one flat surface, with all four corners visible.

1. Download the angled mosaic sample and open it with File› then Open… Right-click the crop-group button and choose Perspective Crop. Its handles start at the photo’s four corners.
2. Drag each handle to the matching corner of the mosaic’s outer border. Keep the corners in order around the surface so the edges do not cross.
3. The real panel is square. Set Width and Height to 800 each, so the corrected tiles keep square proportions. For other surfaces, use their real proportions; 0 lets the editor calculate that dimension from the frame.
4. Click Apply perspective crop or press Enter or ↩. If the grid still looks skewed, undo and place the corners more carefully.

Check the tile lines and small detail inside the result. Perspective correction recalculates pixels and can soften detail; it cannot recover anything out of focus or hidden behind another object.

Keep the crop editable

With Delete cropped pixels unticked, cropping changes the canvas boundary and hides what falls outside it. Choose Image› then Reveal All to expand the canvas around the hidden image areas. Save a File› then Save As› then Lil Cactus Project… copy if you need those areas after reopening.

A JPEG or PNG export contains only the cropped canvas. Opening that exported file cannot bring the missing edges back. Keep the original photo or the editable project.

Fix common problems

The crop is stuck as a square

Ratio is set to 1 : 1. Choose Free to draw any shape, or select the ratio you need.

The tram or person looks stretched

Crop to the target ratio before resizing. In Image Size, keep the chain link on. For Perspective Crop, check both the corner positions and the output proportions.

The crop button is disabled

With the ordinary Crop tool, draw a frame first. In Perspective Crop, make sure the four corners are distinct and the sides do not cross.

Finish the cropped image

• Set precise dimensions: resize the image.
• Meet a file-size limit: compress the image.
• Make a round avatar: crop a circular profile picture.
• Keep transparent corners or edges: make the background transparent.

Coming from another editor

Photoshop

Crop tool in the toolbar, with Ratio and Straighten on the options bar. Perspective Crop is in the same toolbar group.

GIMP

Tools › Transform Tools › Crop, with Fixed › Aspect ratio in Tool Options.

Image cropping: questions and answers