0 Replies Latest reply on Jan 22, 2015 5:10 AM by drewgill

    Lens Correction Profile ImageYCenter

    drewgill

      The short:

      Where does an Adobe lens correction profile place the principal point (u0,v0) for a 1920x1080 pixel image (width x height), an ImageXCenter of 0.5, and an ImageYCenter of 0.5?

       

      The long:

      This question concerns placement of the principal point when using an Adobe lens correction profile. 

       

      As described in Rectilinear Geometric Distortion Model Descriptors for the Adobe Camera Model (page 13),

      • Let Dmax be the maximum of the reference image width or height in the number of pixels.
      • ImageXCenter = u0 / Dmax. (If absent, default to 0.5. Need to be multiplied by the Dmax of the target image when applying the model for lens correction.)
      • ImageYCenter = v0 / Dmax. (If absent, default to 0.5. Need to be multiplied by the Dmax of the target image when applying the model for lens correction.)

       

      Consider a 1920x1080 pixel image, with row & column zero at the upper left of the image.  By the definitions above:

      • Dmax is 1920
      • ImageXCenter = 0.5 would place u0 at column 0.5*1920 = 960
      • ImageYCenter = 0.5 would place v0 at row 0.5*1920 = 960

       

      Is this understanding correct?  Further, would v0 be placed at the bottom of the image (row 960) or the top of the image (row 1080-960 = 120)?

       

      Thanks in advance for the help!