WINDOW AND LEVEL **************************************************************



This button opens a dialog box for adjusting the grey mapping of the image.

The control allows several choices to be made.  The usual mode of operation is

to use the sliders to adjust the tonal mapping.  There are three types of

curves available:  Window and Level (W&L), Brightness and Contrast (B&C) and

what we term Arizona Contrast (AzC).  These curves are selective using the

corresponding radio buttons.  Another way to select the curve parameters,

besides using the sliders, is to enter the desired values in the edit boxes at

the top of the dialog box. The Window and the Level edit controls accept entries.

The First and the Last greylevel are calculated from those entries. Although the

resolution of the controls are only 256 steps, the values entered correspond to

the bit-depth of the images. For example, a 16-bit image will have a mid-level

of 32768. This option makes it possible to exactly repeat adjustements.



The two, non-editable boxes grouped under statistics show the results of a

realtime calculation of the Mean and Standard Deviation over the entire image.

The values are limited to eight-bit precision and are intended only for non-

quantitative usage.  For quantification, use the image and display statistics

under the analysis button.



The RESET button returns the palette to the standard mapping. The Apply button

functions only when W&L is selected.  It causes the Original Image to be mapped

to the Processed Image using a lookup table corresponding to the palette

adjustment.



The check box for 'Hard Palette', whe checked, causes the hardware palette to be

manipulated.  If this box is not checked, the adjustment is done by software.

Naturally, the manipulation using hardware is much faster.



The  button, located near the bottom of the dialog box  labeled 'Sixteen Bit'

lauches another dialog box that does a mixed hardware-software manipulation to

a sixteen-bit depth.  That dialog box has two buttons, a coarse and a fine

adjustment.  The buttons move in two-directions controlling the brightness and

contrast respectively. The Reset-Coarse button sets the tonal mapping to linear

over the full gray range and eresets foth the Coarse and Fine controls.

The Reset-Fine button remaps only the fine-portion of the tonal transfer

curve.  The apply button maps the Original image through a lookup table into

the processed image and then copies the Processed image into the Original image.

The lookup table performs the mapping that had been selected by the Window

and Level operation and makes the change permanent.  The Goto Soft (Hard) button

toggles between the hardware and software lookup tables.  When the hardware

palette is unavailable, the button is disabled.



At the very bottom of the WindowAndLevel dialog box is the 8-bit two-

dimensional control.  It is a single button whose vertical motion controls the

level setting and horizontal motion controls the window setting.





This help file was updated on October 27, 2000.