To switch among the Develop module’s tools, use the buttons on the top panel. Clicking a tool shows settings for that tool; clicking it again hides them. To apply a tool’s settings, click Apply or press [Enter]. To go back to the settings from before you activated the tool, click Cancel or press [Escape]. To restore any tool to its default state, click the arrow icon at the top of the tool.
If the tool works with a mask, then a mask list is shown towards the top of the Side Panel. Click an item to set a mask to work with. To add a new mask, click Add Mask. To Delete a mask at any time, click the button with the trash-can icon to the right of the mask list or in the right-click menu for a mask. That menu also contains items to Rename or Duplicate a mask. Use the checkbox next to a mask’s name to disable or re-enable it. Hover the mouse over a mask’s name to temporarily highlight the mask in blue in the picture. To display a mask permanently, use the Mask button at the top of the panel.
Rotate and Crop [C]
Use the Crop controls to set a fixed aspect ratio for the cropping rectangle. The default is Current Aspect. You can choose from several predefined ratios of sides in the list, or enter a ratio numerically. Next to the drop-down list, there is a button for adding your frequently-used ratios of sides to a list.
Use the Rotation control to rotate a picture to a precise angle numerically. Next to the slider, there is a button for setting the picture’s horizon [H] – click it and draw out a line in the picture, and the picture will be rotated so as to make that line horizontal (or vertical, if it is closer to the vertical). The Crop Marks menu contains a list of marks that can be shown in the preview area. To quickly toggle among marks, press [Tab].
Press [X] to flip the cropping frame’s ratio of sides, thus changing the orientation of the crop (between landscape and portrait).
Press [Shift+A] to stretch the cropping frame to the largest size supported by the picture’s orientation—if the cropping frame’s current orientation does not match the picture’s orientation, its orientation is changed to match.
Straighten Lines [K]
This serves primarily for correcting converging lines in a picture. To perform this correction, either use the sliders in the Side Panel or work directly inside the picture, by dragging out guidelines to match the lines in the picture that you want to straighten. A maximum of two vertical and two horizontal lines can be placed. The program automatically straightens the picture as you add lines. However, you can safely reposition the lines afterwards. To remove lines, right-click or press [Delete].
Because total straightening can sometimes look unnatural, you can soften the correction using the Intensity slider.
Gradient filter [G]
Use this group to add gradient filters to a picture. Any number of them can be added. When this group is opened up, one gradient filter is already automatically added to the picture. To reposition it, click and drag anywhere in the picture. The direction dragged sets the filter’s angle of rotation. The length dragged sets the length of the gradient. Both values can later be changed with the mouse. After a filter has been dragged out, it can be adjusted using the sliders on the right.
Radial Filter [R]
The Radial Filter works similarly to the Gradient Filter, except that the filter mask is defined by an ellipse that can then be adjusted.
Filter Brush [B]
Use the Filter Brush for local adjustments to settings as with the previous filters. Make brush strokes to set where the adjustments go. To erase part of the mask, switch to Remove from Mask mode. Switch to this mode using the Brush Parameters section. The brush can have different settings in each mode—to prevent this, turn on Shared Brush Settings.
Retouching Brush [J]
Use this to retouch away image defects, using either a clone stamp or a retouching brush. To set the source area used for retouching, hold down [Ctrl] and click in the picture. Alternatively, the program can choose a source area automatically. With default settings, each left-click creates a new brush stroke. Switch to Add to Mask or Remove from Mask mode to edit the current brush stroke. To switch modes temporarily, hold down [Shift] or [Alt]. The brush can have different settings in both modes—to prevent this, use the Shared Brush Settings option.
To select individual brush strokes, click the source or target mark. Both the source and target can be repositioned. You can change the brush type later. When a given stroke is made up of only a single mouse click, you can also later change its other brush settings.