lvtilt(3)              C LIBRARY FUNCTIONS              lvtilt(3)



LIBRARY ROUTINE
     lvtilt - Adds a  specified  plane  to  the  input  image  to
     correct for a tilt in the image luminance.

LIBRARY CALL
          #include "vinclude.h"
          int
          lvtilt(img1,img2,mflg,xslope,yslope)
          struct xvimage  *img1, *img2;
          int             mflg;
          float           xslope, yslope;

INPUT
     img1           (struct xvimage) - input/output image xvimage
                    structure

     img2           (struct xvimage) - input mask image

     mflg           (int) - set to one if img2 to is to  be  used
                    as a mask image

     xslope & yslope
                    (float) - specify the characteristics of  the
                    plane and must be given in units per pixel.

OUTPUT
     img1           (struct xvimage) - input/output image xvimage
                    structure

     lvtilt will return a value of one upon success and a zero on
     failure.

MODIFICATIONS
     John Rasure, Marcelo Teran, Donna Koechner
     Mon Jun 11 16:53:44 MDT 1990 Donna  Koechner  -  updated  to
     ghostwriter
     Fri Jun 28 16:43:19 MDT 1991 Scott  Wilson  -  Fixed  bogous
     pointer increment in float loop with mask

DESCRIPTION
     _l_v_t_i_l_t adds a specified plane to the input image to  correct
     for a tilt in the image luminance.  Often an image will have
     a skew in the grey level values that represents a plane with
     a  certain  slope.  The tilt takes the form of a plane which
     has a X and Y zero crossing at the center of the input image
     with xslope and yslope as specified in the argument line.

     img1 is the input and output xvimage structure. This is done
     to  save  space,  but  you  must be careful not to overwrite
     important data.  img2 is the mask image, if mflg is set then
     the  mask  image  is used to gate the operation.  A non-zero
     mask pixel enables  the  ouput  pixel  to  contain  adjusted



University of New MexicoLast change: 06/28/91                     1






lvtilt(3)              C LIBRARY FUNCTIONS              lvtilt(3)



     values.  A  zero  mask pixel just transfers the value of the
     corresponding pixel in the input image to the output  image.
     The input images must be of the same data type and size.

     xslope and yslope specify the characteristics of  the  plane
     and must be given in units per pixel.

     The output image data type is the same  as  the  input  data
     type.

     _l_v_t_i_l_t returns a value of one upon success  and  a  zero  on
     failure.

SEE ALSO
     vtilt(1),  intro(3),  vipl(3),  verror(3),  vutils(3)  vget-
     tilt(1), lvgettilt(3), vdetilt(1), vdetilt(3)

RESTRICTIONS
     _l_v_t_i_l_t will not operate on COMPLEX or BIT data storage  type
     images.

AUTHOR
     Scott Wilson, Donna Koechner


COPYRIGHT
     Copyright  1991,  University  of  New  Mexico.   All  rights
     reserved.



























University of New MexicoLast change: 06/28/91                     2