DDJVU(1)

💅 DDJVU(1) — the DjVu decoder, but make it a group chat

okay so bestie, sit down, hydrate, because we're about to talk about ddjvu — that's the Command line DjVu decoder from the DjVuLibre era, and she is lowkey iconic. this is the ddjvu(1) manual page, rewritten with love, but every single fact is still in here. no cap. 🫶

✨ SYNOPSIS ✨

ddjvu -format=fmt [options] [djvufile] [outputfile]

like, that's the whole vibe. one format, some options, a file in, a file out. slay.

🌸 DESCRIPTION 🌸

So what she does is: decode the DjVu file djvufile, and produce the image file outputfile. that's the whole job. she's a decoder, she's booked and busy. ✨

Now, the tea about where the data comes from:

• The DjVu data is read from standard input when the argument djvufile is not specified, or when it's equal to a single dash. 😌
• Same energy for output: the output data is written to standard output when the argument outputfile is not specified, or equal to a single dash.

but bestie, listen — a valid output file name is always required when you're producing a TIFF or PDF file. no exceptions, no vibes-based workarounds. 🚫

👑 MAIN OPTIONS 👑

these are the main character options. the ones that actually run the show. 💅

• -format=fmt — this one sets the output file format, and honestly? she's the moment. The recognized file formats are pbm, pgm, ppm, pnm, rle, tiff, and pdf. here's the breakdown, no skimming:
  • Formats pbm, pgm, and ppm respectively produce a Portable Bitmap (PBM), Portable Graymap (PGM), or Portable Pixmap (PPM) file. Format pnm is the flexible queen — she produces a PBM, PGM, or PPM output file according to the color content of the output image. 🎨
  • Format rle produces a compact run length encoded bitonal file that is understood by the DjVuLibre commands cjb2 and csepdjvu. iykyk. 🍓
  • Format tiff produces a Tagged Image Format (TIFF) file using lossless compression. Enabling lossy JPEG compression (see option -quality below) often produces much smaller files. Commands tiffcp(1) and tiffsplit(1) are useful for manipulating the resulting TIFF files. teamwork makes the dream work. 🫶
  • Format pdf produces a Portable Document Format (PDF) file. Each page in the resulting file is represented by an image at the specified resolution, using lossless compression. Enabling lossy JPEG compression (see option -quality below) often produces much smaller files. An alternate way to produce PDF file consists in first using djvups(1) and convert the resulting PostScript file to PDF. Which method gives better results depends on the contents of the DJVU file and on the capabilities of the PS to PDF converter. two paths, both valid, choose your fighter. ⚔️

okay and this part matters: when option -format is not specified, the extension of argument outputfile has no influence on the default output format. Instead the program behavior is modified to ensure backward compatibility with previous versions of ddjvu. We recommend to always specify the output format using this option. fr fr, just say the format. 💀

• -page=pagespec — tells her which pages should be decoded. When this option is not specified, all pages of the documents are decoded and concatenated into the output file. The page specification pagespec contains one or more comma-separated page ranges. A page range is either a page number, or two page numbers separated by a dash. For instance, specification 1-10 outputs pages 1 to 10, and specification 1,3,99999-4 outputs pages 1 and 3, followed by all the document pages in reverse order up to page 4. she can go backwards, she's talented like that. 🔥
• -eachpage — When this option is specified, program ddjvu generates one separate file per page, named by replacing the %d specification in outputfilename by the page number in a manner simular to the printf(3) function. yes, it says "simular" in the original. we keep it. 💖
• -mode=mod — Selects which layers of the DjVu image should be rendered. Valid rendering modes are color, black, mask, foreground, and background. the lineup:
  • Rendering mode color is the default mode. When the DjVu file is bitonal, bitonal or gray-level output is produced depending on the subsampling factor. Otherwise a color image is produced. 🌈
  • Rendering mode black is useful to extract a meaningful black and white image. bitonal or gray-level output is produced depending on the subsampling factor. 🖤
  • Rendering modes mask, foreground, and background select specific layers of a DjVu image. These modes can fail if the DjVu image does not contain the selected layer. so, gentle heads up. 😭
• -skip — Instead of aborting when encountering a corrupted page, this option causes ddjvu to simply skip the corrupted page and continue with the next. This is useful for processing certain damaged files. she's resilient, she's healing, she moves on. 🧚

📐 RESOLUTION OPTIONS 📐

The following options control the resolution of the output image. The default resolution is the native resolution of the DjVu file, equivalent to selecting -1. so if you say nothing, she gives you the real thing, untouched. 💅

• -n — Specify an integer sub-sampling factor. The dimensions of the full output image will be n times smaller than the DjVu image size. The legal values for argument n range from 1 to 12. Option -1, for instance, produces an output image whose resolution is equal to the resolution of the input DjVu image file. (yes, -1 and -n collide a lil bit. it's fine. it's a whole thing. 🙈)
• -subsample=n — This is equivalent to option -n. same girl, different name. 💅
• -scale=mag — Specify a magnification factor relative to the resolution stored in the DjVu image. Specifying magnification of 100 produces an image suitable for displaying on a 100 dpi device such as a computer screen. The magnification factor mag can also be interpreted as the resolution of the output image expressed in dot per inch. it's giving "screen-ready". ✨
• -size=wxh — Specify the size of the full output image. Rendering the full DjVu image would create an output image whose width and height would not exceed w and h. To change the aspect ratio, you must also use option -aspect=no. they're a package deal bestie. 🎀
• -aspect=yesno — This option indicates whether the image aspect ratio should be preserved. The defaults is to preserve the aspect ration. (yes, "ration". we're keeping the typo, it's part of the lore. 💀) This option permits changes in the aspect ratio when used in combination with option -size.

🦋 OTHER OPTIONS 🦋

the little extras. the accessories to the outfit. 💜

• -verbose — Display informational messages describing the structure of the DjVu image and the format of the output file. she'll tell you everything, she's an open book. 🫶
• -segment=wxh+x+y — Specify an image segment to render. Program ddjvu conceptually renders the full page using the specified resolution, and then extracts a sub-image of width w and height h, starting at position (x,y) relative to the bottom left corner of the page. Both operations of course happen simultaneously. Rendering a small sub-image is much faster than rendering the complete image. The output file will always have size wxh when this option is specified. efficiency queen. ⚡
• -quality=factor — Enables lossy JPEG compression for TIFF and PDF files. This option only affects images that cannot be encoded using the preferred TIFF/G4 compression. Argument factor is a quantization factor ranging from 25 to 150. See command cjpeg(1) for more information on JPEG quantization factors. Value 80 is a good starting point. 🌸
• -quality=uncompressed — Completely disables compression in TIFF and PDF files. Although the resulting files are often huge, this is sometimes useful for maximal compatibility with hastily written software. (we've all met that software. 👀)
• -quality=deflate — Enables DEFLATE compression for TIFF files. Images that cannot be encoded using the preferred TIFF/G4 compression will be encoded with DEFLATE compression if available. Otherwise the more portable PACKBITS compression is used. Specifying this option is not necessary for PDF files because this is the default behavior. ✨

💀 DEPRECATED OPTIONS 💀

Various options have been maintained to ensure backward compatibility with previous versions of ddjvu. Here's the lore, and here's why you should NOT touch it:

• When option -format is not specified, the program only decodes the first page of the document and the default resolution becomes -scale=100.
• Options -size, -scale, -segment, and -page accept an argument separated by a space.
• Options -foreground, -background, and -black are shorthands for the -mode=mod option.

Please do not rely on these features. like, genuinely. they're legacy. let them rest. 🪦

🌈 EXAMPLES 🌈

Command

ddjvu -format=tiff myfile.djvu myfile.tif

decodes all pages and produces a multipage TIFF file. multipage!! she ate. 👑

Command

ddjvu -format=ppm -page=1-10 -eachpage -size=100x100 myfile.djvu
thumb%03d.ppm

produces 100x100 thumbnails for the first ten page of a document and outputs them as PPM files named thumb001.ppm to thumb010.ppm. thumbnail factory, honestly. 🎀✨

🫶 CREDITS 🫶

The new version of this program was written by Léon Bottou <leonb@users.sourceforge.net>. legend behavior. 💖

This program includes code derived from program tiff2pdf, written by Ross Finlayson and released under a BSD license. credit where credit is due, always. 🌸

👀 SEE ALSO 👀

djvu(1), djview(1), pnm(5), pbm(5), pgm(5), ppm(5), cjpeg(1), tiffsplit(1), tiffcp(1), printf(3)

go read those too, bestie, the whole family is iconic. 📚

and that's the page!! this was DjVuLibre-3.5, dated 10/19/2002, and she's still serving after all these years. mwah. 💅✨🎀