Hello!
I'm in real trouble, and I think that the answer is very close to me, but I can't get it by myself...
Here is my problem:
I'm currently improving the PDF parser that I've made, adding support for cross reference streams. After a careful reading of the ISO 32000 specification (with PDF 1.7 in background), I've wrote a piece of code that decode the stream and build the corresponding objects (I use Java).
But the decoded values are meaningless, and I don't understand why!
The data are like that:
filter predictor: 12
encoding : Flate
fields length : 1 2 1 (this is the W entry values)
column size : 4
I assume that there is one color per pixel formed by one byte.
First, I 'deflate' the data, then 'unfilter' them. Both operations look ok as I've made test for the Flate encoding (ok), and the for the filter I've use it with PDFBox source (and my work unfiltered well what PDFBox filtered...).
Note that I compared my outputs with those produced by PDFBox, and they are the same... Something may be wrong in the parameters I use, but I no idea now...
I think I missed out something as I read incorrect data as entry type 18...
I don't know where to go now, after a whole week of work!
If any have an idea, I'd be grateful to hear it!
I'm in real trouble, and I think that the answer is very close to me, but I can't get it by myself...
Here is my problem:
I'm currently improving the PDF parser that I've made, adding support for cross reference streams. After a careful reading of the ISO 32000 specification (with PDF 1.7 in background), I've wrote a piece of code that decode the stream and build the corresponding objects (I use Java).
But the decoded values are meaningless, and I don't understand why!
The data are like that:
filter predictor: 12
encoding : Flate
fields length : 1 2 1 (this is the W entry values)
column size : 4
I assume that there is one color per pixel formed by one byte.
First, I 'deflate' the data, then 'unfilter' them. Both operations look ok as I've made test for the Flate encoding (ok), and the for the filter I've use it with PDFBox source (and my work unfiltered well what PDFBox filtered...).
Note that I compared my outputs with those produced by PDFBox, and they are the same... Something may be wrong in the parameters I use, but I no idea now...
I think I missed out something as I read incorrect data as entry type 18...
I don't know where to go now, after a whole week of work!
If any have an idea, I'd be grateful to hear it!