Trim To Size
The Trim To Size method is used to crop the images to a smaller size. Trimming, or "cropping" occurs after all quantitative changes (i.e., bias, dark correction, etc.) have been made to the images. This method is part of the Image Calibration pipeline.
The trimming region may be explicitly specified in the dialog or it may be obtained from the image header, as follows:
To let the image header declare the trimming region, check the Use Trim Keyword option and enter the name of the keyword to use. The name TRIMSEC is commonly used for this quantity but there is no standard keyword for this purpose. The name DATASEC is also sometimes used.
To specify the trim region explicitly, uncheck the Use Trim Keyword option and enter the column and row limits. Remember that Mira uses 1-based pixel coordinates so that pixel (1,1) is the origin of the image array.
Calibrate Images, Methods Page, Crop Image, Image Coordinate System