Default value: Varies according to scanner model. See Appendix B for details.
Explanation:
This command specifies the scanning area as a rectangle measured from the origin, with lengths for the main scan and sub scan. The setting is made in units of dots (pixels).
The maximum values are determined by the current resolution (ESC R) and zoom (ESC H) settings. The values available for the scanning area depend on the scanner model, and can be calculated using the maximum scannable area and the maximum resolution values obtained with the ESC I command.
The values for parameters denote:
n1: main scan offset length (2 bytes)
n2: sub scan offset length (2 bytes)
n3: main scan reading length (2 bytes)
n4: sub scan reading length (2 bytes)
Offset lengths and scanning length
The offset lengths determine the offsets of the starting point of the specified scanning area, as measured from the origin. When these values are 0, the scanning area starting point is the origin. When they are specified as 10 dots each, the scanning area starts from dot 11 for the main scan and sub scan.
The scanning length determines the length and width of the scanning area, starting from the origin or from the offset position.