Cropping is the process of removing parts of an image, reducing the visible area. As a result of the crop process, portions of the image outside the crop frame, defined by you, will be removed, leaving only the rectangular area inside the frame.
As JPEG images are composed of a number of independently encoded units typically 8x8, 8x16 or 16x16 pixels in size, it is possible to crop the image along the unit boundaries and save it later without recompression of the units, thus avoiding degradation.
To crop the image enter the Crop mode by clicking the Crop icon on the main toolbar or select the Edit->Crop item in the main menu or Crop item in the context menu. You can use the C key as a shortcut for this command.
You can select a crop preset in the Crop Presets combobox . There are basically three types of crop presets:
- Free crop - the crop rectangular is not restricted by aspect or size.
- Fixed aspect - width to height ratio of the crop rectangular is fixed, e.g. 4:3.
- Fixed size - the crop rectangular width and height are fixed, e.g. 800x600 px
Select a crop area by holding the primary mouse button down and dragging it (for free and fixed aspect crops) or by clicking at the desired position (for fixed size crops). The selected area will be outlined by a dashed rectangular. Release the mouse button once you have the desired area selected. If the Save Selected Block Position option is set on the Crop tab of the Preferences (File->Preferences->Crop), the crop area will appear at the last used position immediately on entering the Crop mode (for fixed aspect and fixed size crops).
Top and left of the crop area are always aligned with MCU blocks boundaries to avoid JPEG recompression.
You can resize the crop area (free and fixed aspect crop) by dragging a border or corner with the primary mouse button down or by entering the exact width/height number in the textbox on the Crop toolbar.
You can swap the height and the width of the area selected by checking the Flip Aspect checkbox.
You can move the crop area by dragging the inside of the area with the primary mouse button down.
You can cancel the current selection by pressing Esc or clicking the Cancel button on the Crop panel or in the context (right-click) menu.
You can also cancel the current selection and start a new one by holding the primary mouse button down and dragging it starting from the outside of the current selection (the Allow New Selection While Current Exists option should be set in Crop Preferences).
To accept the current selection and crop the image double-click on the selection, or click OK button on the Crop panel or in the right-click context menu, or press Enter.
You can select between different Guidelines such as "Rule of Thirds" or "Golden Mean" that will show over the crop area during selection and will help you in achieving a better image composition.
Ctrl+Shift+F shortcut can be used to switch fading of the cropped area on/off.
To change crop preferences go to File->Preferences->Crop Pane.