<#4235#>Operations between two images or two spectra:<#4235#>
In this form, the command word is followed by the numbers of the buffers
holding the images. Examples are
The FLAT word is used in the DIVIDE command to re-scale the division by the
mean of the second image, thus preserving the mean of the first buffer.
This is typically used when dividing raw images by a flat field.
NOTE: The mean of the second image must have previously been
calculated by the MN command!
<#4236#>Operations between images and constants:<#4236#>
In this form, there is only one buffer specification on the command line.
The word CONST= (or C=) is used to specify the constant to be used.
<#4237#>Combined image and constant operations:<#4237#>
The first two forms of these commands may be combined, thus allowing you to
simultaneously operate on two images and a constant.
<#4238#>Remarks:<#4238#>
In two-image arithmetic, only those pixels common to the two images are
changed by the operation. The size of the destination image is not changed
by the operation. The DR= and DC= keywords only apply to two-image
arithmetic and specify row and column offsets between the two images. The
sense of the shift is shown in the following example: dest(C+DC,R+DR) =
dest(C+DC,R+DR) + other(C,R).
BOX limits the operation to those pixels in the destination image which are
in the specified box.
Note that the first buffer listed is the one modified by the operation.