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badbollsjoe
Participating Frequently
April 15, 2011
Question

Postscript editing with Ghostscript

  • April 15, 2011
  • 1 reply
  • 5002 views

Hi,

I am a student that is currently working with a project where we are supposed to read something from a postscript file and place it in a new postscript file.

I want to edit a postscript file with the help of ghostscript to make an output with certain values I have picked out of the original postscript file.

Right now I have a file that does this, but I want to get the fonts that are embedded in a hexadecimal string and decode it so I get the ASCII symbol from it.

The original file have objects that look something like this

/g5 <1C60D8A8C9B64EDFFB83C6241DB110BEE5AB2FAD9D94B39ED5E81E7411B

66E9361DDE78FC667AB91EF9824>

And what I want to do is to pick them out and check them against some dictionary in the postscript code (systemdict???) and pick out its value.

Does anyone have something like this or an example to do this?

Right now my code to pick out the file starts something like this:

(%stdout) (w) file def

where I get the file and now I want to search for let's say the string "<1C60D8" and copy everything that is between this and the symbol ">"

After that I want to check what the hexadecimal code hides underneath it, which in this case is a "E" in Arial.

If anyone have any info on how to do this I would be very happy.

Best regards.

This topic has been closed for replies.

1 reply

Mr__Horton
Mr__Horton
Inspiring
April 15, 2011

I'm having a little trouble following what exactly you want to accomplish and why.

Not to be critical, but in this case, it seems like you are going to a lot of trouble to access information in an odd way.

Maybe a more thorough explaination of both your starting point (why you need to search using a hexadecimal string, and where it comes from) and ending point (what you do with a resulting ascii character in the font), would set me straight on your project. I apologize if you have exactly outlined an assignment that you were given.

However:

With PostScript code the objects you referred to can be converted to strings and scanned for matching values, parsed into substrings, etc. whether you store them in a separate file or not. Using PostScript font encoding/handling procedures you can calculate/process/retrieve character parameters using ascii, or hexadecimal, or octal values as your starting point. 

B
badbollsjoeAuthor
Participating Frequently
April 18, 2011

Hi!

I want to extract the text so I can have it in a new file without the hexadecimal strings and in pure ASCII format. So <hexadecimal> becomes a "P" for example.

After that I can make a software that picks out the "P" from the new postscript file and puts it on my homepage, and the final result is a homepage with everyones test results from the last exam for example.

Right now I am using ghostscript and the following command line which I found on the internet somewhere to extract the information in the file.

gswin32c.exe -q -dNODISPLAY -dNOPAUSE -sFONTPATH=C:\WINDOWS\Fonts -dBATCH extract.ps input.ps > output.ps

where extract.ps is the file in which I need to do some encoding to retrieve the hexadecimal string and encode it and lastly output it so it becomes an "normal" font, and also write in some coordinates of where they should lie.

If you have any knowlegde of how I should start that would be awesome. Right now I am thinking that this probably wont work and I'll have to do another approach like the other students, but since I found out that PostScript is a programming language I thought I could make it.

Right now I am  thinking I probably need to do something like this in the beginning.

(%Stdout)(w)

test{

     <hexadecimal string>

     dup ????

     writestring

     check against systemdict?

     gcheck??

     <end of hexadecimal string>

    } bind def

show test???

I am currently trying to read some literature that I found on the internet but it is very difficult!

If you know how to solve the problem, with an example, please let me know

Best regards!

Mr__Horton
Mr__Horton
Inspiring
April 18, 2011

I would prefer to do what you want to do with a more general purpose language, such as "C", for instance, probably like the other students.

However, that doesn't mean it can't be done with PostScript and I think I can probably help you with your project, and broaden our understanding of PostScript and what it is capable of.

Can you post (or email) a complete input file for me to look at?

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