You (or third) can now develop custom comparators for HP QTP bitmap checkpoints. A comparator is a COM object that helps in performing the bitmap comparison for the Quicktest checkpoint to suit your testing requirements. For example, you could define a customized comparator that allows a bitmap checkpoint to pass, even if the image changes in the application of a specified amount when the checkpoint is set.

After you install and register a comparator on the computer QTP, your comparator is available for selection in the Properties dialog box Bitmap Checkpoint. The dialog box provides a space to indicate preferences for additional configuration expected by your comparator.

When QTP Bitmap checkpoint using a comparator, it provides bitmaps expected and achieved the purpose comparator. It then receives & reports the results that the custom compares returns.