Resizing and Cropping

To access the editing tools, open an image and then click the Edit File toolbar button (the palette icon).

Two tools are provided to resize and crop images.

Resize: This allows you to resize the image. The image may be scaled to a certain physical size, or to a certain percentage of the original size. The aspect ratio may be locked to a specific value, or freely adjusted.
Crop: This allows you to crop the image. Click and drag the mouse over the desired area of the image. The area may be locked to a specific aspect ratio, or it may be freely adjusted. A rule-of-thirds grid or golden-sections grid may be superimposed over the image for composition guidance.

gThumb also offers a batch-mode tool for resizing multiple images simultaneously. See Resizing Images.