First, open a picture editor, such as the Microsoft Office picture manager that comes with the system.

2. Find the "Edit Picture" tool button, click it to enter the picture editing mode, and then click "Resize", as shown below:

3. Click "Custom Width x Height", set the width to 300 and the height to 400, and then click "OK". After confirmation, save the picture as, and you can get a picture of about 30K pixels.