9 ms·

What’s the point of this in 2018 - now that PDF is an open ISO standard?

zeth___ 8y ago
It is much better optimized for scanned documents than PDF.
xelxebar 8y ago
Djvu are often a lot smaller in size than the corresponding PDF. I have a lot of math texts in electronic form and the difference is pretty dramatic.
mindslight 8y ago
From my own playing around figuring how I wanted to archive scanned documents, it's both smaller and much quicker to load. But going out on a limb with a format doesn't instill confidence for long term. It's great there's one "perfect" implementation that seems to just work, but perceived lack of an ecosystem is still worrying. Not that looking through the source of say libjpeg instills confidence either! I was also considering JP2 for nicer-looking artifacts, but couldn't bring myself to go that route. I eventually just increased my size budget (because disappearing a ream into 5GB is still damn useful!), and decided to just store lossless FLIF at 300dpi. I statically compiled the flif binary, do a test decode to make sure the bits round trip, and store checksums of the decoder binary and raw raster alongside. I then stuff this into a zip container (aka .cbz), along with some really poor jpg thumbnails so present evince can view it. I still need to write the transcoder to .djvu - when I'm no longer buried under piles of paper!
gwern 8y ago
I've been scanning a lot of books and switched over a while ago - you get books which can be 10x smaller, and which load and display faster too. And if you desperately need a PDF for some reason, they can be converted back easily.
mnl 8y ago
I've been using it for years. For scanned materials it's simply better: files are smaller, rendering is snappy, and if you're into old books its background/foreground model really pays off. Quite strange this scepticism here about good old djvu. Better fetch a book from the Internet Archive in both formats and check for yourselves why it's a thing.
- CamperBob2 8y ago
  There's just no need for it. 50 years from now, you are not going to have any trouble finding a .PDF viewer, but DjVu is a different question entirely.
  - milesokeefe 8y ago
    Your chances of things working would be much better with PDF as well given that the PDFA version is sometimes used.
  - mnl 8y ago
    Tell me how I can remove the background of a yellowed old book I have to read or print for my research side-project with a PDF file. I don't understand dismissive generalisations about a tool coming from people that don't use it. For the purpose it was designed for it does the job better than a format designed for an entirely different thing. Frankly I don't expect having to read PDF files 50 years from now, but if I were thinking about preservation, the timeproof archiving medium still is acid-free paper –better yet, vellum– and probably India ink. As for the need of any technology, beyond stone tools and fire nobody really needs anything, it's just convenient.
    - CamperBob2 8y ago
      Tell me how I can remove the background of a yellowed old book I have to read or print for my research side-project with a PDF file. I think you may be confusing tools with file formats. There are any number of ways to do this with .PDFs, none of which I've personally had to explore. Frankly I don't expect having to read PDF files 50 years from now, but if I were thinking about preservation, the timeproof archiving medium still is acid-free paper –better yet, vellum– and probably India ink. As for the need of any technology, beyond stone tools and fire nobody really needs anything, it's just convenient. Meanwhile, back on this planet...
      - mnl 8y ago
        I just can open this djvu file with a viewer and display foreground, done. I can focus on reading it, which is the whole point of me accessing this file. I don't have to process a bloated PDF version with any other tools you just don't even know, me neither. Exactly, in this planet we still can read, for instance, books printed by Gutenberg, yet try to convert some Word files rotting in a low-density macintosh floppy from 25 years ago. Paper beats everything else because it's a passive medium that lasts centuries and comes with all the hardware you need. A computer file needs a whole ecosystem and being copied around often. Will we even use files in 2068? I don't know. Maybe in 2047 PDFs will be out of mainstream support because 99% of customers will be using the next better format or workflow.
bsaul 8y ago
i don't know about djvu format, but being in the process of writing a pdf parser atm i can tell you there's definitely some room for a simpler file format than pdf. The size of the specification is daunting, and i still encounter weird behaviors for some documents on some major platform's reader ( and now that i've read part of the spec i definitely understand why). Something a little more up to date and more focused on today's technologies would be really nice.
- jacquesm 8y ago
  Interesting, are you starting from scratch or building on poppler or something like it? I am writing a PDF parser too and am building on top of poppler to do the heavy lifting.
  - bsaul 8y ago
    I’m building something on ios to extract text only from pdf along with some basic rendering features ( text position and font info, something that big commercial libraries don’t provide curiously ). So i’m using apple core foundation lib to do the basic parsing and use a project called pdfkitten as a starting point for font to unicode decoding and text positionning. I also plan to add obvious heuristics for « words » building later on as well as a global index for all the rendered blocks ( all done in swift). Images, forms, etc, are completely out of the scope. It’s a very specific and ( hopefully) narrow need and is the only reason i’m starting this project in the first place.
    - magduf 8y ago
      This is a little off-topic but you seem like a good person to ask: Do you know a way to crop a PDF? Basically, if I have a PDF of a single letter-size page with a 6x9 label on it, and I'd like to crop it down to that 6x9 label only, is there a way to do this? I've been looking into this with, for instance, the poppler library, and haven't found anything.
      - bsaul 8y ago

It is much better optimized for scanned documents than PDF.

Djvu are often a lot smaller in size than the corresponding PDF. I have a lot of math texts in electronic form and the difference is pretty dramatic.

mindslight 8y ago

From my own playing around figuring how I wanted to archive scanned documents, it's both smaller and much quicker to load. But going out on a limb with a format doesn't instill confidence for long term. It's great there's one "perfect" implementation that seems to just work, but perceived lack of an ecosystem is still worrying. Not that looking through the source of say libjpeg instills confidence either! I was also considering JP2 for nicer-looking artifacts, but couldn't bring myself to go that route. I eventually just increased my size budget (because disappearing a ream into 5GB is still damn useful!), and decided to just store lossless FLIF at 300dpi. I statically compiled the flif binary, do a test decode to make sure the bits round trip, and store checksums of the decoder binary and raw raster alongside. I then stuff this into a zip container (aka .cbz), along with some really poor jpg thumbnails so present evince can view it. I still need to write the transcoder to .djvu - when I'm no longer buried under piles of paper!

gwern 8y ago

I've been scanning a lot of books and switched over a while ago - you get books which can be 10x smaller, and which load and display faster too. And if you desperately need a PDF for some reason, they can be converted back easily.

mnl 8y ago

I've been using it for years. For scanned materials it's simply better: files are smaller, rendering is snappy, and if you're into old books its background/foreground model really pays off. Quite strange this scepticism here about good old djvu. Better fetch a book from the Internet Archive in both formats and check for yourselves why it's a thing.

CamperBob2 8y ago
There's just no need for it. 50 years from now, you are not going to have any trouble finding a .PDF viewer, but DjVu is a different question entirely.
- milesokeefe 8y ago
  Your chances of things working would be much better with PDF as well given that the PDFA version is sometimes used.
- mnl 8y ago
  Tell me how I can remove the background of a yellowed old book I have to read or print for my research side-project with a PDF file. I don't understand dismissive generalisations about a tool coming from people that don't use it. For the purpose it was designed for it does the job better than a format designed for an entirely different thing. Frankly I don't expect having to read PDF files 50 years from now, but if I were thinking about preservation, the timeproof archiving medium still is acid-free paper –better yet, vellum– and probably India ink. As for the need of any technology, beyond stone tools and fire nobody really needs anything, it's just convenient.
  - CamperBob2 8y ago
    Tell me how I can remove the background of a yellowed old book I have to read or print for my research side-project with a PDF file. I think you may be confusing tools with file formats. There are any number of ways to do this with .PDFs, none of which I've personally had to explore. Frankly I don't expect having to read PDF files 50 years from now, but if I were thinking about preservation, the timeproof archiving medium still is acid-free paper –better yet, vellum– and probably India ink. As for the need of any technology, beyond stone tools and fire nobody really needs anything, it's just convenient. Meanwhile, back on this planet...
    - mnl 8y ago
      I just can open this djvu file with a viewer and display foreground, done. I can focus on reading it, which is the whole point of me accessing this file. I don't have to process a bloated PDF version with any other tools you just don't even know, me neither. Exactly, in this planet we still can read, for instance, books printed by Gutenberg, yet try to convert some Word files rotting in a low-density macintosh floppy from 25 years ago. Paper beats everything else because it's a passive medium that lasts centuries and comes with all the hardware you need. A computer file needs a whole ecosystem and being copied around often. Will we even use files in 2068? I don't know. Maybe in 2047 PDFs will be out of mainstream support because 99% of customers will be using the next better format or workflow.

bsaul 8y ago

i don't know about djvu format, but being in the process of writing a pdf parser atm i can tell you there's definitely some room for a simpler file format than pdf. The size of the specification is daunting, and i still encounter weird behaviors for some documents on some major platform's reader ( and now that i've read part of the spec i definitely understand why). Something a little more up to date and more focused on today's technologies would be really nice.

jacquesm 8y ago
Interesting, are you starting from scratch or building on poppler or something like it? I am writing a PDF parser too and am building on top of poppler to do the heavy lifting.
- bsaul 8y ago
  I’m building something on ios to extract text only from pdf along with some basic rendering features ( text position and font info, something that big commercial libraries don’t provide curiously ). So i’m using apple core foundation lib to do the basic parsing and use a project called pdfkitten as a starting point for font to unicode decoding and text positionning. I also plan to add obvious heuristics for « words » building later on as well as a global index for all the rendered blocks ( all done in swift). Images, forms, etc, are completely out of the scope. It’s a very specific and ( hopefully) narrow need and is the only reason i’m starting this project in the first place.
  - magduf 8y ago
    This is a little off-topic but you seem like a good person to ask: Do you know a way to crop a PDF? Basically, if I have a PDF of a single letter-size page with a 6x9 label on it, and I'd like to crop it down to that 6x9 label only, is there a way to do this? I've been looking into this with, for instance, the poppler library, and haven't found anything.
    - bsaul 8y ago