Resizing an image on a Mac is quite simple, using Preview, a built-in image utility that can be used for free in OS X. Preview helps you easily crop images and adjust their dimensions without having to install additional software. Learn how to resize your photos, remove unwanted areas, and adjust image resolution using Preview.
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Method 1 of 2: Resizing Images with Preview
Step 1. Find the image you want to resize
This method will help you resize the entire image. If you want to crop part of the image to resize it. Check out how to Crop an Image with Preview.
To search for an image name or label, open the Finder and click the icon with a magnifying glass in the menu. Type your search criteria and press Return to display the search results
Step 2. Drag the image to the Preview icon in your Dock or Image Finder will open in Preview
You can also right-click the image and select “Open With”, then “Preview.”
Step 3. Click the edit button (pictured in pencil) to switch to Edit Mode
This will launch a new toolbar at the top of the Preview window.
Step 4. Click the “Tools” menu and select “Adjust Size”
Step 5. Change the image resolution
Image resolution is measured in pixels per inch (also called “dots per inch” or “dpi”). If you are printing an image or just want to keep the quality as high as possible, consider increasing the resolution.
- If your image will be used for the web or an application such as Facebook, please use the native resolution (72). If you start with a higher resolution, reducing the resolution will reduce the image file size.
- If you plan to print images in a high-quality format, for example for advertising or other forms of business communication, set the resolution to at least 600. Note: your file size will increase significantly.
- To print glossy photos (glossy), a resolution of 300 is enough. The file size will be much larger than the standard 72 dpi file, but the final quality will be what you want.
Step 6. Specify the width and height in the boxes provided
The larger the width and height of the image, the larger your file data will be.
- To make it easier, change the unit of measurement to give your image the best visualization. For example, you can change it to “cm” if you want to specify the width in centimeters. Click the menu right next to the Width (width) and Height (height) to select the desired unit.
- If you want, you can select a size as a percentage of the current size. Select “Scale”, then select a percentage from the drop down menu.
Step 7. Check the box next to “Scale proportionally” to prevent your image from being disproportionately
This step is optional, but you can use it to ensure that changing the width of the image also changes its height. This ensures the image retains its original proportions.
Step 8. Click OK to view the image in its new size
If you are not satisfied with the result, press Cmd+Z to restore it.
Step 9. Press Command+S to save the image changes
After you finish resizing the image, don't forget to save your work.
- If you want to save the resized image as a new file, click “File”, then “Save As,” then enter a new file name.
- If you notice an error after saving the image, click " Revert To " on the File menu and select " Browse All Version …" Select the previous version of the image you want to restore.
Method 2 of 2: Crop Image with Preview
Step 1. Click the Edit icon (the icon with a pencil drawing) to enter Edit Mode
Step 2. Click the dotted rectangle icon on the editing toolbar, then select " Rectangular Selection"
Step 3. Click and drag on the part of the image you want to save
After releasing the mouse button, you will notice that the dots that form a rectangle appear over a portion of the image.
Step 4. Click the Crop button
By doing so, you will delete all parts of the image that are outside the rectangular selection.
- You can resize the cropped image as desired.
- If you don't want to save the image changes, press Cmd+Z to restore them.
Step 5. Press Cmd+S to save your file
- If you want to save the cropped image as a new file (and keep the original image in its original form), Click “File,” then “Save As,” and enter a new file name.
- To restore an image that has been saved to a previous version, click “File,” then “Revert To,” and select “Browse All Versions …” Now, select an image from the previous version.
