code: def wcs_pix_transform(ct, i, format=0):
      
      z1 = float(ct.z1)
      z2 = float(ct.z2)
      i = float(i)
  
      yscale = 128.0 / (z2 - z1)
      if (format == 'T' or format == 't'):
          format = 1
  
      if (i == 0):
          t = 0.
      else:
          if (ct.zt == W_LINEAR):
              t = ((i - 1) * (z2 - z1) / 199.0) + z1
              t = max(z1, min(z2, t))
          else:
              t = float(i)
      if (format > 1):
          t = (z2 - t) * yscale
      return (t)
docs: Computes the WCS corrected pixel value given a coordinate
      transformation and the raw pixel value.
  
      Input:
      ct      coordinate transformation. instance of coord_tran.
      i       raw pixel intensity.
      format  format string (optional).
  
      Returns:
      WCS corrected pixel value