Scale Menu

The Scale Menu is used to set the upper and lower limits and the distribution of colors, based on pixel values.

Min Max

Set the upper and lower limits to the min and max values. The image may be scanned to determined these values, based on the Min Max Options.

IRAF ZScale

Set the upper and lower limits base on the IRAF ZScale algorithm. ZScale parameters may be configured via the preference menu. see ZScale Parameters.

User Limits

Set the upper and lower limits via a interactive dialog box. The user may specify the limits manually. A histogram function is also available, to help determine optimal limits.

Scope

For FITS Mosaics, scope specifies if the limits are applied global across each FITS Mosaic segment, or on a per segment basis.

Min Max Options

Specify the method to be used to determine the min and max data values.

Scan Data-- scan the entire image to determine the min and max values.

Sample Data-- sample the entire image to determine the min and max values. Parameters to control this process can be configured via the preferences menu. See MinMax Parameters.

DATAMIN DATAMAX-- use the DATAMIN DATAMAX keywords, if present to determine min and max values.

IRAF-MIN IRAF-MAX-- use the IRAF-MIN IRAF-MAX keywords, if present to determine min and max values.

Sample Parameters

Select the increment  interval for determining the min and max data values. The larger the interval, the quicker the process is.

ZScale Parameters

Select the parameters for the IRAF ZScale algorithm.

Linear

Set the colors distribution to Linear.

Log

Set the colors distribution to Log.

Squared

Set the colors distribution to Squared.

Square Root

Set the colors distribution to Square Root.