Cursor Positioning

Cursor Positioning

The basic cursor menu provides simple interactive positioning of a cursor on the current output buffer. Both the position of the cursor (in all four coordinate systems) and the intensity of the pixel at the cursor are displayed as the cursor is moved around. Optionally the routine may zoom into the buffer, enlarging it by factors of 1, 2, 4 or 8. These zoom parameters may be retained or reset on exit, depending on the method of exit chosen.

If a mouse is installed, then the mouse may also be used to adjust the position and zoom of the cursor.

The current cursor position is displayed in all four coordinate systems (current pixel, reference pixel, world and reference world). The intensity of the pixel under the cursor, the average intensity in a region 5x5 pixels centred on the cursor, and the standard deviation of the intensity within this region are also displayed, rounded to the nearest integer value.

<up> Move the cursor up by the current step amount (see S for changing step size).

<down> Move the cursor down by the current step amount.

<left> Move the cursor left by the current step amount.

<right> Move the cursor right by the current step amount.

1 Move the cursor left and down by the current step amount.

4 Move the cursor left by the current step amount.

7 Move the cursor left and up by the current step amount.

8 Move the cursor up by the current step amount.

9 Move the cursor right and up by the current step amount.

6 Move the cursor right by the current step amount.

3 Move the cursor right and down by the current step amount.

2 Move the cursor down by the current step amount.

5 Move the cursor the the centre of the buffer by the current step amount.

delete Move to initial position.

page up Move to top of buffer.

page down Move to bottom of buffer.

home Move to left of buffer.

end Move to right of buffer.

C Condense buffer. Reduce the magnifcation of the buffer by a factor of 2. The minimum magnification is 1x.

E Enlarge buffer. Increase the magnification of the buffer by a factor of 2. The maximum magnification is 8x.

S Toggle the step size between 1 and 16 pixels per step.

M Set the cursor coordinates manually. The cursor position may be specified in either the Pixel or World coordinate system.

T Toggle cursor on/off. The display of the cursor may be suppressed or enabled with this option.

V Enable mouse <=> no VTR control. This option will disable the VTR control (if currently active), allowing the use of a serial mouse, if such a mouse is fitted.

I A limited form of pixel-by-pixel editting is available within the cursor menu. This option allows the intensity of the Z option plotting to be specified. The chosen intensity may be used to set the pixel value, or to And, Or or XOr with the value already there.

Z This option will set the intensity of the current pixel to that specified by the I option above. Note that if a point is changed using this option, and an offboard buffer is being used, both the temporary onboard and permanent offboard copies will be modified.

MOUSE - Available only if Video routines not enabled:

Left button - Exit and restore previous zoom Middle button - Change zoom Right button - Exit and maintain present zoom Left+Right - Exit and reset to no zoom Left+Middle+Right - As for left button.

P Exit and maintain present zoom.

Q Exit and restore previous zoom.

R Exit and reset to no zoom.


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DigImage User Documentation


Stuart Dalziel, last page update: 19 February 1996