PowerShell Requires Chilkat v11.7.0+

Remove a PDF's Old Revisions

See more PDF Optimization Examples

Demonstrates dropOldRevisions. A PDF that has been edited and saved several times carries every earlier revision: the superseded objects are still in the file, reachable through the older cross-reference sections. The audit reports them as "oldRevisions", and dropping them is often the single largest saving in a real document. Dropping them requires a full rewrite, which is why it invalidates existing digital signatures. PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  The PDF used in this example is available at grand_canyon_hiking_guide.pdf

$pdf = New-Object Chilkat.Pdf
$success = $pdf.LoadFile("qa_data/pdf/grand_canyon_hiking_guide.pdf")
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

#  How much of this file is superseded revisions?
$json = New-Object Chilkat.JsonObject
$jsonOut = New-Object Chilkat.JsonObject
$success = $pdf.Optimize("audit",$json,$jsonOut)
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

$("fileSize:     " + $jsonOut.IntOf("fileSize"))
$("oldRevisions: " + $jsonOut.IntOf("usage.oldRevisions.bytes"))

#  Drop them, and nothing else, so that the saving is attributable.
$json.UpdateBool("compressUncompressed",$false)
$json.UpdateBool("recompressFlate",$false)
$json.UpdateBool("replaceLegacyFilters",$false)
$json.UpdateBool("imagePredictors",$false)
$json.UpdateBool("dedupeStreams",$false)
$json.UpdateBool("dedupeObjects",$false)
$json.UpdateBool("removeUnreferenced",$false)
$json.UpdateBool("removeUnusedResources",$false)
$json.UpdateBool("removeUnusedLayers",$false)
$json.UpdateBool("coalesceContent",$false)
$json.UpdateBool("tidyContent",$false)
$json.UpdateBool("subsetFonts",$false)
$json.UpdateBool("dropOldRevisions",$true)

$success = $pdf.Optimize("optimize",$json,$jsonOut)
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

$success = $pdf.WriteFile("qa_output/grand_canyon_one_revision.pdf")
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

#  The saving is an estimate: what the old revisions occupied is known exactly, but the writer
#  decides the final layout.  Measure the written file for the real number.
$fac = New-Object Chilkat.FileAccess
$("bytesSaved (reported): " + $jsonOut.IntOf("bytesSaved"))
$("written file:          " + $fac.FileSize("qa_output/grand_canyon_one_revision.pdf"))