# phpman > perldoc > Image::ExifTool::Fixup

## NAME
    [Image::ExifTool::Fixup](https://www.chedong.com/phpMan.php/perldoc/Image%3A%3AExifTool%3A%3AFixup/markdown) - Utility to handle pointer fixups

## SYNOPSIS
        use [Image::ExifTool::Fixup](https://www.chedong.com/phpMan.php/perldoc/Image%3A%3AExifTool%3A%3AFixup/markdown);

        $fixup = new [Image::ExifTool::Fixup](https://www.chedong.com/phpMan.php/perldoc/Image%3A%3AExifTool%3A%3AFixup/markdown);

        # add a new fixup to a pointer at the specified offset in data
        $fixup->AddFixup($offset);

        # add a new Fixup object to the tree
        $fixup->AddFixup($subFixup);

        $fixup->{Start} += $shift1;   # shift pointer offsets and values

        $fixup->{Shift} += $shift2;   # shift pointer values only

        # recursively apply fixups to the specified data
        $fixup->ApplyFixups(\$data);

        $fixup->Dump();               # dump debugging information

        $fixup->IsEmpty();            # return true if no offsets to fix

## DESCRIPTION
    This module contains the code to keep track of pointers in memory and to shift these pointers as
    required. It is used by ExifTool to maintain the pointers in image file directories (IFD's).

## NOTES
    Keeps track of pointers with different byte ordering, and relies on
    [Image::ExifTool::GetByteOrder](https://www.chedong.com/phpMan.php/perldoc/Image%3A%3AExifTool%3A%3AGetByteOrder/markdown)() to determine the current byte ordering when adding new pointers
    to a fixup.

    Maintains a hierarchical list of fixups so that the whole hierarchy can be shifted by a simple
    shift at the base. Hierarchy is collapsed to a linear list when ApplyFixups() is called.

## AUTHOR
    Copyright 2003-2022, Phil Harvey (philharvey66 at gmail.com)

    This library is free software; you can redistribute it and/or modify it under the same terms as
    Perl itself.

## SEE ALSO
    Image::[ExifTool(3pm)](https://www.chedong.com/phpMan.php/man/ExifTool/3pm/markdown)