Controlling the view


You can zoom the main image by one of several methods:
  1. Press the button with a large "Z" on it.
  2. Press the "Scale:" button and choose from one of the numbered zooms.
  3. Place your mouse cursor into the "Pan" window (the small one on the upper left) and press buttons 1 and 2.
  4. Drag out a region in the main window using shift-drag mouse button 1.
  5. Pressing control while moving a mousewheel.
Unzooming uses the button with a small "z", or you can pick a smaller number from the "Scale:" options, or finally you can press button 3 in the pan window. Unzooming using option 4) uses shift mouse button 2. Unzooming using option 5) is done by moving the mouse wheel in the opposite direction.

The zoom can only be changed by integer amounts.


The part of the image that you see (assuming that you cannot see the whole image) can be controlled by several methods:

  1. By dragging the scrollbars, left to right and top to bottom.
  2. By moving the box displayed in the pan window (the small window on the upper left). To move this place your cursor over the box and then press and keep down button one -- now move the mouse around and finally release the button.
  3. By dragging-scrolling the main image. To do this press button 2 down and keep it down over the main image. Moving the mouse now pans the image in the same direction as the cursor.
  4. Moving a mouse wheel, either up-down or, if you have one left-right. If you don't have a left-right wheel shift up-down will also scroll left to right.

On slow machines 2) is probably the best option.

Changing the image detail

Setting the display range (also known as the cut levels) changes the limits of the data that correspond to the brightest and faintest parts of your image. You can change the display range in many different ways.

  1. Press one of the "Auto Cut" buttons (try this first).
  2. Open the "View" menu and select the "Cut Levels ..." option. This show a histogram of the values in the image and allows some preset cuts to be applied.
  3. Type in the limits in to the "Low:" and "High:" boxes on the front panel. Just press to activate them.

Manipulate the image colours:

You can manipulate the displayed colours by actions in the colourmap display (the bar of colours in the lower part of the main screen). These actions are.

  1. Press and hold down button 1, then move the mouse side to side. This shifts the colourmap.
  2. Press and hold down button 2, then move the mouse side to side. This stretches the colourmap.
  3. Press the shift key and button 1 together and hold down, then move the mouse side to side. This rotates the colourmap.
  4. Pressing button 3 resets the colourmap to the default.

Change the image colours:

You change the image colourmap by opening the "View" menu and selecting "Colors...". This creates a new window in which you can select from a large set of preset colourmaps. You can also select an intensity transfer function, and a colour scale algorithm.

Change the number of colours used:

You can increase and reduce the number of colours used to display the image by opening the "View" menu and selecting "Colors...". A new window is created by allows you to change the number of "Allocated Colors". This control has no effect when working with more than 8 bits (the number of colours is automatically set to 256 in this case).