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HowcanIextractembeddedfontsfromaPDFasvalidfontfiles?
31
1
c:\> mutool.exe extract filename.pdf
OnLinux,Unix,MacOSX:
1
$>
mutool
extract filename.pdf
8.4 Method 4: Using
gs
(Ghostscript)
Finally,Ghostscript⁴canalso extractfontsdirectlyfromPDFs.However,itneedsthe help ofaspecial
utilityprogram named
extractFonts.ps
,writteninPostScriptlanguage,whichisavailablefromthe
Ghostscriptsourcecoderepository⁶.
Now use it, you needto run both, thisfile
extractFonts.ps
andyour PDF file. Ghostscriptwillthen
usethe instructionsfromthe PostScriptprogramtoextractthefontsfromthe PDF.Itlookslikethison
Windows(yes,Ghostscriptunderstandsthe‘forwardslash’,/,asapathseparatoralsoonWindows!):
1
gswin32c.exe
^
2
-q -dNODISPLAY
^
3
c:/path/to/extractFonts.ps ^
4
-c "(c:/path/to/your/PDFFile.pdf) extractFonts quit"
oronLinux,UnixorMacOSX:
1
gs
\
2
-q -dNODISPLAY
\
3
/path/to/extractFonts.ps \
4
-c "(/path/to/your/PDFFile.pdf) extractFonts quit"
I’vetestedthe Ghostscriptmethodafewyearsago.Atthetime itdidextract*.ttf(TrueType)justfine.I
don’tknowifotherfonttypeswillalsobeextractedatall, andifso,inare-usableway.Idon’tknowif
theutilitydoesblockextractingoffontswhicharemarkedasprotected.
http://www.ghostscript.com/releases/
http://git.ghostscript.com/?p=ghostpdl.git;a=blob_plain;f=gs/toolbin/extractFonts.ps
http://git.ghostscript.com/?p=ghostpdl.git;a=tree;f=gs
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HowcanIextractembeddedfontsfromaPDFasvalidfontfiles?
32
8.5 Caveats:
• Inanycaseyouneedtofollow thelicensethatapplies tothefont.Some fontlicences do
notallowfreeuseand/ordistribution.Piratingfontsislikepiratinganysoftwareorother
copyrightedmaterial.
• Most PDFs which are inthe wild out there donot embed the fullfont anyway, but only
subsets.Extractingasubsetofafontisonlyusefulinaverylimitedscope,ifatall.
PleasedoalsoreadthefollowingaboutProsand(more)Consregardingfontextractionefforts:
• http://typophile.com/node/34377
How to C#: Preview Document Content Using XDoc.Word
How to C#: Preview Document Content Using XDoc.Word. Get Preview From File. You may get document preview image from an existing Word file in C#.net.
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How to C#: Preview Document Content Using XDoc.PowerPoint
How to C#: Preview Document Content Using XDoc.PowerPoint. Get Preview From File. You may get document preview image from an existing PowerPoint file in C#.net.
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9How can I get Ghostscript to use
embedded fonts in PDF?
HereisthecommandIuse:
1
gs
\
2
-o output.pdf
\
3
-dCompatibilityLevel=1.4 \
4
-dPDFSETTINGS=/screen
\
5
-sDEVICE=pdfwrite
\
6
-sOutputFile=output.pdf \
7
input.pdf
Iamusing(tryinganyway)touseGhostscripttoreducemyPDFfilesize.Thecommandabove
lookslikeitworks,itreducesfilesizegreatly,butthenseveralofthefieldsaregarbled.Asforas
Icantrackitdown,it’sdoingfontsubstitution.IE,thesametext=samegarbledtext.
ThefontsareembeddedinthePDFwhenitgetstome.Additionally,Ihavetriedtoaddallthe
fontstotheFontmap.
Anyideas,IdeallyIwouldlikeittousetheembeddedfontswithoutmehavingtoupdatethegs
systemfonts/editfontmap,etc.I’musingUbuntu9.10andtheFontsembeddedarewindowsfonts,
Arial/TimesNewRoman.
9.1 Answer
EmbeddingfontsretrospectivlywhichwerenotembeddedintheoriginalPDFdoesincreasethefilesize,
notdecreaseit.
However,theremaystillbeachancetoreducetheoverallfilesizebyreducingtheresolutionofembedded
images…dependsonyourpreferencesandneeds.
Youcan trywith variationsofthe following commandline. Itwill embedall fonts (eventhe “Base 14”
ones),butembedrequiredglyphsonly(a“subset”oftheoriginalfont),andalsocompressthefonts:
1
gs
\
2
-o output.pdf
\
3
-dCompatibilityLevel=1.4 \
4
-dPDFSETTINGS=/screen
\
5
-dCompressFonts=true
\
6
-dSubsetFonts=true
\
7
-sDEVICE=pdfwrite
\
33
VB.NET PDF File Compress Library: Compress reduce PDF size in vb.
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C# WinForms Viewer: Load, View, Convert, Annotate and Edit PDF
Add text to PDF document in preview. • Add text box to PDF file in preview. • Draw PDF markups. Search PDF text in preview. • View PDF outlines.
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HowcanIgetGhostscripttouseembeddedfontsinPDF?
34
8
-c ".setpdfwrite <</NeverEmbed [ ]>> setdistillerparams" \
9
-f input.pdf
YouwillhavenoticedthatIdidusethe
-o output.pdf
conventioninsteadof
-sOutputFile=output.pdf
.
Ialsodidn’tinclude
-dBATCH -dNOPAUSE
inmycommand.Thereasonisthatbothmethodsareequivalent,
since
-o ...
silentlyalsosets
-dBATCH -dNOPAUSE
:
‘Traditional’Ghostscriptoption:
1
-sOutputfile=output.pdf -dBATCH -dNOPAUSE
‘Modern’Ghostscriptoptions
1
-o output.pdf
However,themodernshortcutwayofwritingthecommanddoesnotworkforolderGhostscriptversions.
Ifyoulookintoreducingthe filesizeofPDFsonlyandhavenowparticularlycompellingreasontoset
-dPDFSETTINGS=/screen
,thenthe chapter“HowcanIconvertacolorPDFintograyscale?”mayalsobe
somethingtoconsider.
C# WinForms Viewer: Load, View, Convert, Annotate and Edit
PowerPoint Conversion. • Convert Microsoft Office PowerPoint to PDF (.pdf). Delete annotations from PowerPoint. Select PowerPoint text contents for edit.
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C# PDF insert text Library: insert text into PDF content in C#.net
Supports adding text to PDF in preview without adobe reader installed in ASP.NET. Powerful .NET PDF edit control allows modify existing scanned PDF text.
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III Scanned Pages and PDF
How to C#: Preview Document Content Using XDoc.excel
How to C#: Preview Document Content Using XDoc.Excel. Get Preview From File. You may get document preview image from an existing Excel file in C#.net.
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C# PDF replace text Library: replace text in PDF content in C#.net
Description: Delete specified string text that match the search option from specified PDF page. Parameters: Name, Description, Valid Value.
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10 How can I make the invisible OCR
information on a scanned PDF page
visible?
IhaveaPDFwhichistheresultofscannedpages.Itcontainslotsofnumbers.
Inourorganization’sworkflow,weusuallyscanincomingmaildeliveredbythepostalservice,
archivethemandthenscraptheoriginalpapers.
Havingreadsome recentnewsaboutPDFsresulting fromscansmadewithacertainbrandof
scannersmanglingnumbersbadly,IwanttocheckifthiscanhappenwithOCRtoo.
MyknowledgeaboutOCRofscannedpagesisratherlimited.Myonlyinfoaboutitisthatituses
somehiddenlayertostorethetext.HowcanIun-hidethishiddenlayer?
10.1 Answer
No, OCRinformationaboutscannedpagesisnotstoredinahiddenlayer. LayersinaPDF are quitea
differentconcept.
ButOCR-edtextneverthelessis‘hidden’– buthiddenalongside thesame layer astherestofthe page
content.
Isuggestyoureadthechapterofthisbooknamed“HowcanIuseinvisiblefontsinaPDF?”first.Itgives
youashorttheoreticalbackgroundof“invisibletext”regardingPDF.
TheOCRtextinyourPDFusesTextRenderingMode3(‘Neitherfillnor stroke glyphshapes’).Inorder
tomakethistextvisible,youhavetochangethistextrenderingmodetooneoftheothermodes:
0 Tr
(filltext)
1 Tr
(stroketext)
2 Tr
(fill,thenstroketext)
4 Tr
(filltextandaddtopathforclipping)
5 Tr
(stroketextandaddtopathforclipping)
Myfavorite modeforthisjobwouldbe
1 Tr
.Itwilljustdrawthe outline shape oftheglyphswithout
fillingthem.Irecommendtodothisusingaverythinredline.Thiswayyouwillbeabletoseetheexact
positioningofthetextrelativetothescannedimagewhenyouzoomintothepage.
UnfortunatelyIdonotknowofanycommandlinetoolthatcanachievethis.You’llhavetodiveintothe
PDFsourcecodeandmanipulateitwithatexteditor.
Fortunatelythisismuchmoreeasythanitsoundsatfirst.Wewillusethreestepsforthis:
1. ExpandtheoriginalPDFsourcecodeoftheOCR/scannedPDFusing
qpdf
¹.
¹
http://qpdf.sf.net/
36
HowcanImaketheinvisibleOCRinformationonascannedPDFpagevisible?
37
2. OpentheexpandedPDFsourcecodeinasimpletexteditorandmanipulateit.
3. ‘Repair’the PDF sourcecode (whichhasbecome ‘corrupted’ through our editing)andcopressit
again.
Step1:Expand theoriginalPDF
LookingatthescannedPDFpagemayshowaviewliketheoneinthefollowingimage.
Screenshotshowingtheoriginalscanned/OCR-edPDFpageopenedinAcrobat.
Ifyou’ve readother chaptersofthisbook already, youmaybe familiar with
qpdf
.ItcanexpandPDF
sourcecodeandtransformitintoamodethatmakesitmoreeasytoprocessforhumanbrains(ifthese
brainshaveacquiredsomePDFknowhowbeforehand,oriftheyareguidedwiththehelpofabooklike
thisone).Hereisthecommandtouse:
1
qpdf --qdf --object-streams=disable original-scan.pdf qdf---original-scan.pdf
ThiscreatedanewPDFfilenamed
qdf---original-scan.pdf
whichcaneasilybeopenedandmanipu-
latedbyatexteditor.
Note,incaseyouroriginalPDFhadbinarydatasections(suchasimages,fontsorcolorprofiles),
thesewillnotbeexpandedandwillstillbecontainedinbinaryforminyourexpandedPDF.It
isonlytheothercomponentswhichwereexpanded.Soyourtexteditorshouldbeabletonot
getahangoverfromthesebinarypartsandsaveyoureditedversionwithoutdamagingthese.
HowcanImaketheinvisibleOCRinformationonascannedPDFpagevisible?
38
Step2:OpentheexpandedPDFwithatexteditor
NowopenthenewPDFfileinyourfavoritetexteditor.Searchforallspotswhereyoufindthetextstring
3 Tr
.Itcouldlooklikethis:
1
[....]
2
/F16 7.500 Tf
3
3 Tr
4
1.180 Tc
5
[....]
Modifythesetextstringsandreplacethembythefollowing:
1 0 0 RG 0.1 w 1 Tr
.TheresultingPDF
codecouldthenlooklikethis:
1
[....]
2
/F16 7.500 Tf
3
1 0 0 RG 0.1 w 1 Tr
4
1.180 Tc
5
[....]
Thismodificationwillhavethefollowingeffects:
1 Tr
:thisswitchesthetextrenderingmodeto‘Stroketext’.
0.1 w
:thissetsthestrokinglineforthetextrenderingmodetoaverythinone,0.1pointsonly.
RG
:thissetstheRGBcolormodeforstrokingoperations.
1 0 0 RG
:thissetsthecolorto‘red’forRGBcolors.
NowsavethismodifiedPDFunderanewnamelike
qdf---edited-scan.pdf
.
Step3:‘Repair’themodifiedPDFandcompress itagain
Our editing manipulations will very likely have ‘corrupted’ the PDF. Because we inserted some 15
additionalcharacters(*100RG0.1w*),thePDF’scrossreferencetable(whichholdsalistofallobject
addressesbasedasbyte offsetsfromthefilesstart)willnolongerbe correct.Youcanuse
qpdf
tocheck
forthisproblem:
1
qpdf --check qdf---edited-scan.pdf
Theoutputwillbesimilartothis:
HowcanImaketheinvisibleOCRinformationonascannedPDFpagevisible?
39
1
WARNING: qdf---edited-scan.pdf: file is damaged
2
WARNING: qdf---edited-scan.pdf (file position 717011): xref not found
3
WARNING: qdf---edited-scan.pdf: Attempting to reconstruct cross-reference table
4
checking qdf---edited-scan.pdf
5
PDF Version: 1.3
6
File is not encrypted
7
File is not linearized
Fortunately,manyPDFviewerswillnothavemajorproblemswiththis–they’llautomatically(andoften
silently)calculate anew
xref
sectionforthe PDFanduse thatinsteadofthe oneembeddedinthe file.
YoucantrytoopenthefileasiswithyourPDFviewerandseeifitdoesordoesnotcauseaproblem.
Butto playitsave andmakesure thateach andeveryviewer will openthe manipulatedPDF without
choking,wewilluse
qpdf
againinordertofixthisproblem:
1
qpdf qdf---edited-scan.pdf ocr-made-visible-in-scan.pdf
Ifyoulookattheresultingfile,
ocr-made-visible-in-scan.pdf
,youshouldseesomethinglikethisnow:
Screenshotshowingthemanipulatedscanned/OCR-edPDFpageopenedinAcrobat.ThehiddenOCRtextisnowmade
visibleasthinredoutlines.Zoomingintotheimagewillrevealmoredetails.
HowcanImaketheinvisibleOCRinformationonascannedPDFpagevisible?
40
Zoomingintothemanipulatedscanned/OCR-edPDFpageat800%inAcrobat.
Nice,isn’tit?You’vejustearnedyouryellowbelt inPDF-KungFoomastership.;-)
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