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### 4.3 Image processing window

Figure 4.6 show’s nip2’s main image processing window. Drag with the middle mouse button to scroll the workspace window. Drop a file on to the workspace background (from your file manager) to load that file. If you right-click on the workspace background, a useful menu will appear.

Figure 4.6: | nip2’s main image processing window

Workspace
  This area displays the objects (images, numbers and so on) which are currently loaded into nip2. The workspace is divided into columns of objects which each behave rather like windows: they can be moved around, folded away, loaded, saved and deleted.
Current column
  One column is the current column. This is the column to which all new objects are added. Single-left-clicking on the title bar of a column makes that the current column. See § 4.3.1.
File, Edit, View
  Use the File menu to create or save workspaces, to open workspaces or load other objects into this workspace, to merge workspaces and to recover after crashes (loads last automatically saved workspace). Use the Edit menu to select, group, delete and duplicate sets of objects. Use View to show and hide elements of the main window, and to set the object view mode.
Toolkits
  This menu contains all of the image processing functions which are currently loaded into nip2. They are generally grouped by object type: all of the operations on matricies are under Toolkits / Matrix, for example.

  If you select one of these image processing operations, nip2 will apply that operation to the bottom few items in the current column (however many are necessary — two items for Math / Arithmetic / Add, for example), or alternatively, if you have selected some objects explicitly, it will try to apply the operation to the selected objects. See § 4.3.3. As you move the mouse pointer over menu items nip2 tries to display some helpful information about the operation, including the number and type of arguments the operation expects.

Toolkit Browser
  This side panel shows all the image processing operations again, but this time as a large flat list you can easily browse. Type into the search box at the top to filter operations by keyword. Doubleclick on an item to activate it.
Free space
  This displays the amount of disc space you have left in your temporary file area. See § A if you want to change the directory nip2 uses to store temporary files.

  If you left-click on the label, it changes to display the space nip2 has free internally for performing calculations. You can change this limit in the Preferences workspace. Click again to switch back to disc free.

  If you have objects selected, this area changes to show the names of the selected objects.

Status bar
  As you move the mouse pointer about the window, this bar tries to display useful information about the thing you are pointing at.

#### 4.3.1 Columns

Columns are split into a number of areas:

Column name
  Each column has a name. You can pick any name you like when you make a new column with File / New / Column. There’s no way to rename a column, unfortunately. Objects in the column are named using the column name, plus a number.
Column title bar
  Drag with the left mouse button held down on the column title bar to move the column around the workspace. Double-left-click on the title bar to change the comment attached to the column. Hold down the right mouse button on the column title bar to pop up a useful menu.

  The items in the menu let you edit the caption, select all the objects in the column, make a new column which is a copy of this column, save the column to a file, convert the column into a menu item (see § 4.3.6) and remove the whole column.

Column fold button
  Left-clicking on the fold button folds the column away. Use this to hide columns which you still need, but which you are not interested in just now.
Expression entry
  You can perform calculations by typing expressions directly into this box. For example, try entering the following expressions, and pressing Return:

  2 + 2 A1 + 120 "My cat likes\nlasagne"

#### 4.3.2 Rows

A column holds a number of rows. Each row comes in four main parts, not all of which are visible for all row values. Rows which represent classes have a pair or up/down arrows to the left of the row name button which you can use to control which parts of the row are visible.

Figure 4.7: | Components of a workspace row

Row name button
  Each row has a name. The name is formed from the name of the current column, plus a number.

  If you double-left-click on the row name button, nip2 will pop up a viewer or dialog box for the value of the row. If you left-click, nip2 will select that row and deselect all other rows. If you click on an empty space in the workspace, it will deselect all rows. If you Ctrl-left-click, nip2 will toggle selection of that row. If you select one row and then Shift-left-click on another row in the same column it will select the second row and all the rows in between. If you drag with the left button, you can change the order of rows in a column. Hold down the right mouse button for a useful menu. If you let the mouse linger over a button, a useful tooltip will appear.

Graphic
  If the row’s value is a class, and if the class is an instance of one of nip2’s graphic classes, then nip2 will draw a graphic representation of the row’s value. See § 6.11.2 for a more detailed explanation.
Members
  If the row has a class for a value, then nip2 will draw a sub-column listing the class members. Subcolumn members are in turn rows themselves.
Text
  Finally, the text part normally shows a text representation of the row’s value. If you left-click on the value, it changes to show the formula which generated that value. You can edit the formula and press Return to change it.

  Alternatively, selecting View / Show Formula toggles between displaying values for objects and displaying the formula.

##### Object name colours

nip2 changes the background colour of the row name button to show the state of the row. If background colours are not visible (perhaps your theme turns them off), try turning on the Display LEDs in workspace option in Preferences.

Green means the row is selected (click on the background to unselect), red indicates an error (right-click on the row button ans select Recalculate to see the full text of the error), brown indicates that the row value is out of date and needs recalculating and the various blues indicate parent and child relationships.

#### 4.3.3 Applying operations to objects

There are three ways you can apply image processing operations to objects in your workspace:

1. Select the object you want to apply the operation to by single-left-clicking on the object name. When you single-click, the object name will change colour to show that it is selected, and nip2 will display the name of the selected object at the left end of the status bar (this is useful if the selected object is scrolled off the edge of the window).

   You can select additional objects with Ctrl-left-click and Shift-left-click. This is necessary if you want to use an image processing operation that takes more than one argument.

   Once you have selected the rows (sometimes you need to select them in a certain order), click on the processing operation you want from the Toolkits menu.

2. If there are no objects selected when you click on an image processing operation, nip2 uses the bottom few items (as many as are needed by the operation) in the current column.
3. You can also type your formula directly into the expresion entry line at the bottom of the selected column. Chapter 6 describes the syntax in detail, but it’s approximately C.

#### 4.3.4 Batch processing

If you select a number of rows and then click Edit / Group, nip2 will group the rows together. Now if you select the group and click on an item in the Toolkits menu, nip2 will apply that operation to every item in the group. You can group groups, and you can mix grouped and non-grouped rows freely.

If you save a group, nip2 will write each item in the group to a separate file, incrementing the filename each time.

#### 4.3.5 Error handling

If an object in your workspace has an error (for example, if you are trying to join two images of different types), then the object name button will turn red to show that this object contains an error and the tooltip for the button will show the error message.

#### 4.3.6 Making menu items out of columns

If you make a column that does something useful, you can make it into a menu item by following these steps:

1. Make your column look nice. Drag with the left mouse button on the object name buttons to re-order items in the column, and add comments to explain what are the input fields and what are the output. Double-click on the column title bar to add a helpful title to the column.

   Add a comment by typing your text (enclosed in double quotes) into the line at the bottom of the column. Left-drag the row to the right place.

2. Select Make Column Into Menu Item from the column title-bar menu, see § 4.3.1.

   This will open up a new dialog box which you can use to set a name for your new menu item and the name of the top level menu the item should be added to.

3. That’s it. You’ll be prompted to save your new toolkit when you try to quit nip2. We recommend you just say OK to the suggested location for the file. Edit your menus with the programming window, see § 4.4.

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