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pdfa -c "PDFTron PDFA Manager User Manual.pdf"
The resulting report looks as follows:
To view simple double click on ‘report.xml’ to open it in the browser. You can find the list of all objects that were modified in the column on the right side of the table. You can obtain exactly the same info if you are using 'pdftron.PDF.PDFA.PDFACompliance' class from PDFNet SDK (as shown in PDF/A sample project - http://www.pdftron.com/pdfnet/samplecode.html#PDFA).
In case you are looking for some type of visual indicator you could do a visual diff between the source and PDF/A document.
Please keep in mind that most PDF/A error and resulting changes will not have a visual manifestation and there would not be much to see.
If you would like to determine if converted PDF/A document is
visually different from the original you could use 'pdftron.PDF.PDFDraw' in PDFNet or pdf2image (http://www.pdftron.com/pdf2image/downloads.html)
along with 'compare'
utility from imagemagic (http://www.imagemagick.org/Usage/compare/,
for your convenience you can fetch compare tool from http://pdftron.com/pub/compare.zip
… if this does not work download full ImageMagic from their site).
To
find visual differences run:
pdfa -c my.pdf
pdf2image
my.pdf
pdf2image
my_pdfa.pdf
compare
my1.png my_pdfa1.png diff.png
Attached
is the visual diff that highlights information loss due to loss of the soft
mask (e_PDFA42). The technique could be used for batch & unattended
conversion and validation. By using PDFNet SDK rather than PDF/A Manager you
could also implement something that is more interactive (i.e. without need for
command-line).
