function norh_ext_subimg,index_in,data_in,index_out $
   ,corner,nsize

;+
; NAME:
;       norh_ext_subimg
;
; PURPOSE:
;       extract a sub-image
;
; CALLING SEQUENCE:
;       data_out=norh_ext_subimg(index_in,data_in,index_out,corner,nsize)
;
; INPUTS:
;       index_in: index structure
;       data_in: data
;       index_out: index structure of the extracted data
;       corner: left-bottom corner pixel coordinate
;               of the extracted data
;       nsize: shape of extracted data
;
; OUTPUTS:
;       data_out: extracted data
;
; HISTORY:
;       Writtern 1998-05-29 TY
;-

mx=n_elements(index_in)

x0=corner(0) & y0=corner(1)
x1=x0+nsize(0)-1 & y1=y0+nsize(1)-1

data_out=data_in(x0:x1,y0:y1,*)

index_out=index_in
sunc=norh_cen(index_in)
index_out.norh.solcen(0,*)=sunc(0,*)-corner(0)
index_out.norh.solcen(1,*)=sunc(1,*)-corner(1)
index_out.norh.shape(0,*)=nsize(0)
index_out.norh.shape(1,*)=nsize(1)


return,data_out
end