CODEWITHSUNDEEP
pdf
Юрий Кот
Юрий Кот

Reputation: 139

Understand pdf structure with flatedecode

Good day!

I read documentation on pdf, but I have some global problems.

https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf

I need xref table from pdf file with Cross-Reference Streams.

This is pdf file https://ufile.io/q77el

Part of pdf file: startxref 22827515 %%EOF

This is this part:

6628 0 obj
<<
/W [1 4 1]
/Info 1 0 R
/Root 2 0 R
/Size 6629
/Type /XRef
/Filter /FlateDecode
/Length 3996
/DecodeParms <<
/Columns 6
/Predictor 12
>>
>>
stream
  xÚí]{|ŽåŸç=ïÝf6­LNIŒ³ŒeHŽ;ÙæÜÁ!D¥ƒèWé...
endstream

I found this text, use function gzucompress and have this

$a = gzuncompress(substr($match[2][0],1,-1));

0200 0000 0000 ff02 0200 0000 0301 02ff
0000 000c 0002 0000 000f 7e00 0201 0000
f176 0102 ff00 0000 c2ff 0201 0000 003e
0202 0000 0000 0001 0200 0000 0000 0102
0000 0000 0001 0200 0000 0000 0102 0000
0000 0001 0200 0000 0000 0102 ff00 000d
3bf8 0201 0000 f3c5 0902 0000 0000 0001
0200 0000 0000 0102 0000 0000 0001 0200
0000 0000 0102 0000 0000 0001 0200 0000
0000 0102 0000 0000 0001 0200 0000 0000

txt file

But what this mean? I see /W [1 4 1] means that i need to split the string into 3 parts : 1 byte 4 bytes 1 byte

02 00000000 00 ff 02020000 00 03 0102ff00 00 00 0c000200 00

But this does not work. please, tell me what my next step. Thank you!

Upvotes: 1

Views: 2316

Answers (1)

Юрий Кот
Юрий Кот

Reputation: 139

Answer - predictor information. /Columns 6 - mean that splin on n+1 /Predictor 12 - mean that this is png algoritm

Upvotes: 2

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