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Starting a DynamicCrop Operation

Image View Tool Bar

Keyboard Shortcut

Image Window Context Menu / Image > Mode Main Menu Item

Defining a DynamicCrop Process

Click on a rectangle side or corner and drag to resize it

Click inside the rectangle and drag to move it without changing its size

Click outside the rectangle and drag to rotate it

Click on the center mark and drag to move the center of rotation

Using the Dynamic Crop/Rotate Dialog to Instantiate DynamicCrop

Many times, static crop and rotation procedures are not well suited to a particular image, because both geometrical transforms should be defined in a single operation or none of them would make sense. The DynamicCrop process has been added to PixInsight (including LE) to facilitate a simultaneous crop and rotation mechanism in a highly interactive way.

Dynamic processes are an important category in PixInsight. Contrarily to other process categories, dynamic processes don't use abstract interfaces, but complex interface resources that adapt each process instance to a particular image. DynamicCrop is the only dynamic process included in PixInsight LE 1.0.

Starting a DynamicCrop Operation

For a dynamic crop/rotation to take place, the target image window must be in the Dynamic Crop/Rotate Mode, which can only be selected if the window's current view is its image view, since dynamic cropping cannot be applied to previews. To select this mode, do one of the following:

• Image View Tool Bar
  This is probably the best way to select the Dynamic Crop/Rotate mode:

If the Image View tool bar is not visible, you can show it with the Window > Tool Bars > Image View option of the main menu.

• Keyboard Shortcut
  You can press the Alt-D combination to select the Dynamic Crop/Rotate mode, or just the D key if the active window is an image window.

• Image Window Context Menu / Image > Mode Main Menu Item
  You can also right-click any image view (not preview) to open its context menu, where you can select the Dynamic Crop/Rotate mode from the Mode submenu. Finally, the Image > Mode > Dynamic Crop/Rotate menu item is also available.

To start a DynamicCrop process, click on the desired location of the image view and drag to define an initial cropping rectangle. For example:

When you release the mouse, the Dynamic Crop/Rotate dialog is shown. This dialog includes all of the defining parameters of a DynamicCrop instance: position and dimensions of the cropping rectangle and rotation angle:

Defining a DynamicCrop Process

Note that you can examine and enter different cropping rectangle coordinates on the Dynamic Crop/Rotate dialog by clicking any of the available anchor buttons. The Anchor X and Anchor Y coordinates shown correspond to the location of the specified anchor point on the actual cropping rectangle defined over the image. Width and Height correspond also to the dimensions of the current cropping rectangle. All of these values take into account the current rotation angle.

The Optimize fast rotations check box works exactly the same as its counterpart on the Rotate window. The same is true for the circular graphic, where you can drag to define a rotation angle. See the documentation section on standard and fast rotations for more information.

Any change you make on data in the Dynamic Crop/Rotate dialog results in the automatic update of the cropping rectangle over the image, and vice versa. Both interface elements are synchronized and guaranteed to be coherent.

To modify the cropping rectangle directly over the image, you can:

• Click on a rectangle side or corner and drag to resize it:

• Click inside the rectangle and drag to move it without changing its size:

• Click outside the rectangle and drag to rotate it:

• Click on the center mark and drag to move the center of rotation:

Press Enter to accept and execute the DynamicCrop process, or Esc to cancel. Alternatively, you can click the OK and Cancel buttons on the Dynamic Crop/Rotate dialog.

Using the Dynamic Crop/Rotate Dialog to Instantiate DynamicCrop

The fact that the Dynamic Crop/Rotate dialog is not an abstract interface (because it needs an image window to work) doesn't mean that the object-oriented functionality of PixInsight processes isn't valid for DynamicCrop. Note that there is a process drag object on the Dynamic Crop/Rotate dialog, therefore, you can create process icons with this dialog, the same way you do so with other processing windows in PixInsight.

Process icon instances of DynamicCrop behave exactly as any other process instances, with the exception that you actually need an image to interface with them.