FUNCTION DSKC,sphe,xdiam,ydiam,shft,xc,yc
;
; Rectification of a spectroheliogram SPHE, using input parameters
; xdiam,ydiam,shft,xc,yc, calculated by DISKCOR3.
; Returned: Corrected spectroheliogram
; M. Sobotka, ASU ASCR, 2017
;
si=size(sphe)
sph=sphe
aspect=float(ydiam)/float(xdiam)   ;current aspect ratio

; making the Sun roundish - correction of the x-diameter
sph=congrid(sph,round(si(1)*aspect),si(2),cubic=(-0.5))
si=size(sph)    ; new size

; correction for entrance slit curvature
sph2=sph
for j=0,si(2)-1 do begin
    xx=findgen(si(1))+shft(j)
    rect=interpolate(sph(*,j),xx)
    sph2(*,j)=rect
endfor

; shift the centroid to the centre of image
sphcor=shift(sph2,si(1)/2-xc,si(2)/2-yc)

RETURN,sphcor
END