1. Width and Height. These two options set the size of the resized image.
2. Keep Aspect Ratio. When this option is enabled, the ratio of the width to height is kept the same as the original image. For example, if the original image was 100 x 200 and new size might be 200 x 400.
3. Center. When this option is enabled, the image is expanded or contracted around the center. For expansion, this would mean that new space would be added equally along the left, right, top and bottom of the image. If the option is disabled, the new space would be added along the right and bottom of the image.
4. Apply Button. When you have selected the proper size, pressing the "Apply Button" will change the image size.
5. Reset Button. Pressing the Reset button, restores the Width and Height value to their original settings.