If you'd like to increase the file size and resolution of your image, here are instructions that may help you.
On a Mac
Open up your JPG or PNG image in Preview.
Go to Tools > Adjust Size...
Enter your desired number of inches for the width. We recommend digits in the upper 10s or 20s, or close to the dimensions of the print you want (for example, enter 20" for a 20x24 print). The image height should automatically increase to scale the image proportionally.
Increase the resolution (300 is best for printing).
Click OK and exit Preview to save your changes. In the example above, the image went from 80 KB to 1.7 MB.
On a PC
Open your JPG or PNG image in Paint.
Click the "Resize" button.
Enter your desired value in the Horizontal and Vertical fields. We recommend entering the dimensions of the print you want. Click OK.
Drag your canvas edges to fit the resized image. There should be no extra white space.
Save the image in JPG format.
Open your image in Photoshop.
Go to Image > Image Size...
Enter your desired width, height, and resolution. We recommend entering the dimensions of the print you want (300 pixels/inch is best).
Click OK and export the file as a JPG or PNG.
If you have any questions or would like assistance resizing your images, please email us at firstname.lastname@example.org. We're happy to help!