You can quickly resize an image in an image editing program such as Preview (on a Mac), Paint (on Windows) or Adobe Photoshop.
1. Select Image in the top menu.
2. Click on Image Size.
A window will open displaying the dimensions of your image.
You can view your image size measurements in pixels by clicking on the drop down menus to the right of your size values.
Once you have resized your image, save the changes.
3. File > Save.
1. Select Resize in the top menu.
A window will open displaying the dimensions of your image.
2. Select Pixels and Maintain aspect ratio from the pop up window.
You can change your image size measurements in pixels by clicking in the boxes besides Horizontal and Vertical in the Resize menu.
Once you have resized your image, save the changes.
3. File > Save.