Cropping removes part of an image so that the remaining area fits a specific composition or dimension. It is different from resizing: resizing changes the scale of the whole image, while cropping discards pixels outside the selected area. Precise cropping is useful when you need a defined aspect ratio, a centered subject or an exact pixel rectangle.
What a crop changes
A crop changes the visible composition and reduces the source area. Anything outside the crop rectangle is removed from the output. Keep the original image if you may need those pixels later.
How to crop precisely with Tervilo
- Open the Tervilo Image Cropper.
- Check the source image dimensions.
- Choose the crop area's position.
- Set the required width and height when an exact rectangle is needed.
- Process the crop.
- Inspect the output before publishing or uploading.
Understand crop coordinates
For a typical raster image, the top-left corner represents the start of the coordinate system. The crop rectangle is defined by its starting position and its width and height. The selected rectangle must stay within the source dimensions if you want to avoid cutting outside the image.
Example: create a square from a landscape image
Suppose the source is 1600 × 900 and you need a 1:1 square. A centered square can use 900 × 900 pixels, removing some width from both sides. If the subject is not centered, move the crop area instead of accepting the default center.
Crop before or after resizing?
When the target aspect ratio is different, cropping before final resizing can help you control composition. For a large source, you can also crop the important area first and then resize it to the exact target dimensions. The best order depends on the workflow and quality requirement.
Crop vs resize
If you need the entire scene, resize it. If you need a different shape or want to remove unwanted edges, crop it. Stretching an image to avoid cropping usually creates visible distortion.
Use the destination's required shape
Profile images, cards, product listings and banners can use different shapes. Check the destination requirement before choosing a crop. A 1:1 image for a profile area is a different task from a 16:9 video thumbnail.
Protect important content
Keep faces, logos, text and product details inside the crop. For screenshots or documents, make sure no required text is clipped. For product images, leave enough margin if the destination overlays controls or labels.
Verify the result
Check both dimensions and composition. A technically correct 800 × 800 crop can still be poor if the subject is cut off. Preview the output at the size where it will be displayed.
Common mistakes
- Using resize when the task actually requires a different aspect ratio.
- Cutting off important text or faces.
- Assuming a centered crop is always best.
- Overwriting the original source.
- Ignoring the destination's required dimensions.
Quick checklist
- □ I know the required output ratio or dimensions.
- □ I positioned the crop around the important content.
- □ I kept the original source.
- □ I checked the final dimensions.
- □ I previewed the image in the destination context.
Quick answer
Crop precisely by defining the required area and keeping it within the source image. Use cropping to change composition or aspect ratio, use resizing to change scale, and always keep a copy of the original before discarding pixels.