The PDF/A-1 standard does not specify how compression is performed. What are the permitted compression techniques for PDF/A-1?
The information I have gathered (not sure if all are true)
Also, how to figure out whether a particular file is PDF/A-1a or PDF/A-1b and what kind of compressions are used in that file?
Thanks in advance.
Adobe Acrobat Pro provides preflight profiles for testing whether a PDF file conforms to any of PDF/A or PDF/X standards. There are also options for converting a non-compliant PDF file to any one of those standards if such fixups are possible.
FYI, there are specifications for the different PDF/A and PDF/X specifications that you may purchase (either hardcopy or downloadable PDF files) from ISO.
Thanks for your reply. I have just found out about it few mins ago and I have used acrobat to verify my file and it was successful.
Another follow up question, it would be really helpful if you can shed some light on it.
How do we know which compressions are used for contone images or monochrome images or text in a particular file? After the verification is done is acrobat, is it possible to have a look at the process (like log file) it has gone through?
Thanks in advance.
Another trick in Acrobat Pro is to invoke the Output Preview tool (under “print production”) and choose the Object Inspector instead of the Separations function. Then click on a particular image. You will see what type of compression is used, the image resolution, the color space (including ICC profile if appropriate), etc. That same tool also shows what font a text is formatted in and point size as well as attributes of other PDF objects as well. It is exceptionally useful in determining what you have in a PDF file.
If you want to look at everything at once, under Preflight, pull down Options and invoke Create Inventory. That function will create a monstrous PDF detailing all the objects and features of the PDF file in question!
Had a look at it. It was really helpful.
In page 26 of ISO 19005-1:2005(E), the second last line goes like this, "Writers of conforming files should not use lossy compression, subsampling..."
If this is true, then lossy compression should not be allowed right?
But JPEG is a lossy compression technique and my file uses JPEG compression.
How is this possible? Am I missing something?
Thanks in advance once again...
For better or worse, ISO specifications are written in a language from a parallel universe. After dealing with ISO standards for a while, you learn what specific words really mean. I should know - I am chair of the ISO PDF/X task force and co-chair of the PDF/VT task force.
The word should does not specify a requirement. PDF/A does not prohibit lossy compression.
JPEG is always a lossy compression. There is a mode of JPEG2000 compression that is indeed lossless. Note that JPEG and JPEG2000 are totally different compression schemes. (I believe that PDF/A-1 as well as PDF/X-1a and PDF/X-3, based on older versions of the PDF specification do not permit JPEG2000. PDF/A-2 based on ISO32000-1 and PDF/X-4 based on PDF 1.6 do allow for JPEG2000.)
ZIP compression is lossless.
I have a file in the format of PDF/A-1B created using a MFD. When u click the info button it says "The file you have opened complies with the PDF/A standard and ....."
Then I wanted to verify the standards of the file, but it failed.
Is there any way to find out which feature or thing that made the file verification to reach a failed state?
As PDF/A-2 has only been a standard for about 6 months now, I am not aware of any scanners that are producing PDF/A-2. However, the only advantage of PDF/A-2 for scanning – which is important – is support for JPEG2000.
I have few more questions on preflight.
1. I have created a PDF/A-1B file using an MFD. The verification fails in acrobat 9 but passes in 10.
2. I have created a PDF/A-1A file using an omnipage OCR engine. The verification fails in acrobat 10 but passes in 9.
I can't figure out whether my files actually complying with the standards or not? I am confused.
Thanks in advance.
I have created a file using JBIG2 arithmetic compression, Flate and MRC highcompression is turned off in 300dpi.
The colour and grayscale file gives me "zlib/deflate, JPEG" as filters
The black & white file gives me "JBIG2" as filter.
Is JPEG compression being used in my file?
If yes, Why JPEG compression is used when I specificly selected Flate?
I hope you can help me with this question.
I have 2 files. one uses MMR compression and the other uses MH compression.
But if I check using output preview, they both show the filter as CCITT Group 4 (FAX)
Using which particular tool in adobe I can figure out exactly what compression is being used?