Re: [pdf-devel] Hello

[Abhishek Mishra]

I have read the the filters section of the ISO pdf document, and
looked at the source code as well as the gnupdf documentation on
filter streams.
I've listed my findings in brief below (I've also attached a text file
which contains the same info).
Please look at it and let me know if my approach is correct, there's
anything missing/incorrect etc.

Thanks,
Abhishek

Documentation for filter parameters
------------------------------------

1. ASCII Hex encoder (PDF_STM_FILTER_AHEX_ENC)
--
The ascii encoder uses no parameters.

2. ASCII Hex decoder (PDF_STM_FILTER_AHEX_DEC)
--
The acsii decoder uses no parameters.


3. Run-Length encoder (PDF_STM_FILTER_RL_ENC)
--
The run-length encoder uses no parameters.

4. Run-Length decoder (PDF_STM_FILTER_RL_DEC)
--
The run-length decoder simpy uses the encoder, therefore it uses no parameters.


#########
NOTE:

Parameters specified in the ISO PDF document for the flate and lzw
decoders are given below:
(Mentioned here separately, as the source does not seem to use all the
parameters.)
All parameters are optional.

Param name                    Type
=================    ==================================
Predictor                           integer
Colors                               integer (Maybe used if Predictor > 1)
BitsPerComponent        integer (Maybe used if Predictor > 1)
Columns                          integer (Maybe used if Predictor > 1)
EarlyChange                   integer (LZW only)

#########

5. Flate (zlib) encoder (PDF_STM_FILTER_FLATE_ENC)
--
The flate encoder uses no parameters currently.

6. Flate (zlib) decoder (PDF_STM_FILTER_FLATE_DEC)
--
The flate decoder uses no parameters currently.

7. LZW encoder (PDF_STM_FILTER_LZW_ENC)
--
The LZW encoder uses the following optional parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
EarlyChange                    pdf_char_t *                                   1

8. LZW decoder (PDF_STM_FILTER_LZW_DEC)
--
The LZW decoder uses the following optional parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
EarlyChange                    pdf_char_t *                                   1


#########
NOTE:

Parameters specified for the jbig2 decoder in the iso pdf document.

Param name                    Type
           Default Value
=================    =====================        ==================
JBIG2Globals                  stream
         N/A

#########

9. JBIG2 decoder (PDF_STM_FILTER_JBIG2_DEC)
--
The JBIG2 decoder uses the following optional parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
GlobalStreamsSize        pdf_size_t *                                    N/A
GlobalStreamsBuffer     pdf char t **                                    N/A

#########
NOTE:

The ISO pdf document does not discuss the aesv2 and v2 encoder/decoder
in the filters section.
Although, there is a crypt filter mentioned which uses two parameters
- Name & Type.

#########

10. AESV2 encoder (PDF_STM_FILTER_AESV2_ENC)
--
The AESV2 encoder uses the following mandatory parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
KeySize                             pdf_size_t *
             N/A
Key                                     pdf char t **
                  N/A

11. AESV2 decoder (PDF_STM_FILTER_AESV2_DEC)
--
The AESV2 decoder uses the following mandatory parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
KeySize                             pdf_size_t *
             N/A
Key                                     pdf char t **
                  N/A

12. V2 encoder (PDF_STM_FILTER_V2_ENC)
--
The V2 encoder uses the following mandatory parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
KeySize                             pdf_size_t *
             N/A
Key                                     pdf char t **
                  N/A

13. V2 decoder (PDF_STM_FILTER_V2_ENC)
The V2 decoder uses the following mandatory parameters.

Param name                    Type
           Default Value
=================    =====================        ==================
KeySize                             pdf_size_t *
             N/A
Key                                     pdf char t **
                  N/A

14. MD5 encoder (PDF_STM_FILTER_MD5_ENC)
--
The md5 encoder uses no parameters.

15. A85 encoder
--
This encoder exists only in the source code and is not mentioned in
the documentation.
Although it seems to be related to the ASCII85 filter mentioned in the
ISO PDF document.




2009/9/20 <address@hidden>
>
>   Please ignore the question in my email, I am now able to generate a
>   pdf from the texi document.
>
> Ok.  Note that you can use the build-aux/gendocs.sh script.
>
> --
> Jose E. Marchesi  <address@hidden>
>                  http://www.jemarch.net
> GNU Project       http://www.gnu.org

gnupdf_filters_scratch.txt
Description: Text document