Overview
The Preview app is already installed on all Mac computers and is useful for editing an image before adding it to a WordPress website or an Emma mailing campaign. Editing functions include:
- Resize or crop an image
- Convert the image type (for instance, from TIFF to JPEG)
- Make basic adjustments to lighting and color
Preparing to edit an image
Quick guide
Step 1: Open the image in Preview
- Open Finder and navigate to the image location. Double-click the image to open it.
- If the image does not open in Preview: right-click (control key + click) the image. Select Open With, and select Preview.
Step 2: Create a copy of the original image
Because any edits you make in Preview are automatically saved, we recommend editing a copy rather than the original image. This way, if you make a mistake, you can easily return to the original image.
- In the menu bar, select File and then select Duplicate.
- Preview creates a copy of the image, which you can rename.
Step 3: Use the Markup toolbar to edit the copied image
- In the upper right, click the Markup
icon.
- The Markup toolbar appears at the top. You can begin making edits, which are automatically saved.
- Don't see the Markup icon? Click the More options
icon and select Markup.
Useful editing actions
Action
Usage
Screenshot
Reduce image file size
When to use:
You can reduce the dimensions of an image in order to reduce its file size. For example, images cannot exceed 5 MB if they are being uploaded to WordPress.
How to use:
- Click the Adjust Size
icon.
- Enter a reduced height or width. We recommend using pixels rather than inches, as these images are intended for web and email, not for print.
- Confirm that the "Resulting Size" field meets the requirement, and click OK.
Crop image
When to use:
If you need to change the aspect ratio (for example, the image is rectangular but you need to upload a square image).
How to use:
- On your keyboard, select command and a.
- A frame with adjustable handles (blue dots) appears on the image. Drag these handles to the desired dimensions. As you drag the handles, the updated dimensions appear next to your cursor.
- Once you are happy with the selection, click the Crop
icon.
Convert image file type
When to use
If an image is a less common format (such as HEIC) and you need to convert it to a standard format (typically JPEG or PNG) to upload it to WordPress.
How to use
- In the menu bar, select File, and select Export.
- In the Format field, make a selection.
- Click Save.
Rotate image
When to use:
If the image is not oriented in the correct direction.
How to use:
Click the Rotate Left 
icon in the upper right. You may have to click multiple times to complete the rotation.
Reduce saturation to view contrast
When to use:
Check whether your image will be hard to discern for someone who is color blind or has difficulty with low contrast images. Desaturating the image lets you view contrast without the distraction of colors.
How to use:
- Click the Adjust Color
icon.
- Drag the Saturation slider handle from its center location to the leftmost side.
- Once you're done, make sure to drag the slider handle back to the center. Otherwise, the change will be saved to the image.
