Open again the http://Z4/CIV , choosing the option CIV2. Keep the same image pair (dt) as in CIV1. Activate the decimal shift and deformation options. The other options are not implemented, and Hart has no effect. The search zone is set by the programme to 2 pixels around the previous estimate (so the Isx,Isy and shift parameters have no effect).
Then you can check the results with uvmat, option CIV2. Bad vectors are now indicated by the flag vec_F=4, stating that the programme did not find a correlation maximum inside the search region. You can remove these bad vectors by fix_vel, and then use patch as for CIV1.