The Scale Menu

The scale menu displays a list of available scaling algorithms. Each frame can have a separate scale algorithm, with initialization controlled by the -scale [scalename] command option. Choosing a new scaling algorithm in a frame that is displaying an image causes that image to be rescaled and redisplayed. The new scale algorithm also becomes the default scale for new images in that frame (until changed by choosing another scale option).

Currently, the following scales are supported in the core SAOtng system:

• linear
• log
• wrap
• sqrt
• no scaling
• histogram equalization

All but the last are supported as internal scaling algorithms, i.e., they are integrated into the SAOtng rather than being called as external scaling programs. See Mapping Pixel Values to Screen Intensity for more information.

Users can set the scaling limits for the current frame using the "Set Min/Max for Scaling" menu option. Choices are:

• data scaling: min and max taken from data
• zscale: min and max calculated by IRAF zscale algorithm
• user scaling: min and max entered by the user via a dialog box

The current scale value is displayed below the menu.

Users can add their own scaling algorithms. See Adding Scaling Algorithms to SAOtng.

Last Updated June 14, 1997