CBconvert
Introduction
CBconvert is a Comic Book converter.
It can convert comics to different formats to fit your various devices.
See more screenshots.
Features
- reads CBR (RAR), CBZ (ZIP), CB7 (7Z), CBT (TAR), PDF, XPS, EPUB, MOBI and plain directory
- saves processed files in ZIP archive format or TAR
- images can be converted to JPEG, PNG, TIFF, WEBP, AVIF, JXL, or 4-Bit BMP (16 colors) image format
- rotate, adjust brightness/contrast, adjust levels (Photoshop-like) or grayscale images
- resize filters (NearestNeighbor, Box, Linear, MitchellNetravali, CatmullRom, Gaussian, Lanczos)
- export covers from comics
- create thumbnails from covers by FreeDesktop specification
Download
Using cbconvert in file managers to generate FreeDesktop thumbnails
Copy cbconvert cli binary to your PATH and create file ~/.local/share/thumbnailers/cbconvert.thumbnailer:
[Thumbnailer Entry]
TryExec=cbconvert
Exec=cbconvert thumbnail --quiet --width %s --outfile %o %i
MimeType=application/pdf;application/x-cb7;application/x-cbt;application/epub+zip;application/vnd.comicbook-rar;application/vnd.comicbook+zip;application/x-mobipocket-ebook;application/vnd.ms-xpsdocument;
This is what it looks like in the PCManFM file manager:
Using command line app
  Usage: cbconvert <command> [<flags>] [file1 dir1 ... fileOrDirN]
  Commands:
   convert
      Convert archive or document
    --width
      Image width (default "0")
    --height
      Image height (default "0")
    --fit
      Best fit for required width and height (default "false")
    --format
      Image format, valid values are jpeg, png, tiff, bmp, webp, avif, jxl (default "jpeg")
--archive
Archive format, valid values are zip, tar (default "zip")
    --quality
      Image quality (default "75")
    --filter
      0=NearestNeighbor, 1=Box, 2=Linear, 3=MitchellNetravali, 4=CatmullRom, 6=Gaussian, 7=Lanczos (default "2")
    --no-cover
      Do not convert the cover image (default "false")
    --no-rgb
      Do not convert images that have RGB colorspace (default "false")
    --no-nonimage
      Remove non-image files from the archive (default "false")
    --no-convert
    Do not transform or convert images (default "false")
    --grayscale
      Convert images to grayscale (monochromatic) (default "false")
    --rotate
      Rotate images, valid values are 0, 90, 180, 270 (default "0")
    --brightness
      Adjust the brightness of the images, must be in the range (-100, 100) (default "0")
    --contrast
      Adjust the contrast of the images, must be in the range (-100, 100) (default "0")
    --suffix
      Add suffix to file basename (default "")
    --levels-inmin
      Shadow input value (default "0")
    --levels-gamma
      Midpoint/Gamma (default "1")
    --levels-inmax
      Highlight input value (default "255")
    --levels-outmin
      Shadow output value (default "0")
    --levels-outmax
      Highlight output value (default "255")
    --outdir
      Output directory (default ".")
    --size
      Process only files larger than size (in MB) (default "0")
    --recursive
      Process subdirectories recursively (default "false")
    --quiet
      Hide console output (default "false")
   cover
      Extract cover
    --width
      Image width (default "0")
    --height
      Image height (default "0")
    --fit
      Best fit for required width and height (default "false")
    --format
      Image format, valid values are jpeg, png, tiff, bmp, webp, avif, jxl (default "jpeg")
    --quality
      Image quality (default "75")
    --filter
      0=NearestNeighbor, 1=Box, 2=Linear, 3=MitchellNetravali, 4=CatmullRom, 6=Gaussian, 7=Lanczos (default "2")
    --outdir
      Output directory (default ".")
    --size
      Process only files larger than size (in MB) (default "0")
    --recursive
      Process subdirectories recursively (default "false")
    --quiet
      Hide console output (default "false")
   thumbnail
      Extract cover thumbnail (freedesktop spec.)
    --width
      Image width (default "0")
    --height
      Image height (default "0")
    --fit
      Best fit for required width and height (default "false")
    --filter
      0=NearestNeighbor, 1=Box, 2=Linear, 3=MitchellNetravali, 4=CatmullRom, 6=Gaussian, 7=Lanczos (default "2")
    --outdir
      Output directory (default ".")
    --outfile
      Output file (default "")
    --size
      Process only files larger than size (in MB) (default "0")
    --recursive
      Process subdirectories recursively (default "false")
    --quiet
      Hide console output (default "false")
meta
CBZ metadata
--cover
Print cover name (default "false")
--comment
Print zip comment (default "false")
--comment-body
Set zip comment (default "")
--file-add
Add file to archive (default "")
--file-remove
Remove file(s) from archive (glob pattern, i.e. *.xml) (default "")
Examples
- Rescale images to 1200px for all supported files found in a directory with a size larger than 60MB:
cbconvert --recursive --width 1200 --size 60 /media/comics/Thorgal/
- Convert all images in pdf to 4bit BMP images and save the result in ~/comics directory:
cbconvert --format bmp --outdir ~/comics /media/comics/Garfield/Garfield_01.pdf
BMP format is a very good choice for black&white pages. Archive size can be smaller 2-3x and the file will be readable by comic readers.
- Extract covers to ~/covers dir for all supported files found in the directory, Lanczos algorithm is used for resizing:
cbconvert cover --outdir ~/covers --filter=7 /media/comics/GrooTheWanderer/
- Convert all images to AVIF format:
cbconvert --format avif --quality 50 --width 1280 --outdir ~/comics /media/comics/Misc/
Quality settings
This table maps quality settings for JPEG to the respective AVIF and WEBP quality settings:
| JPEG quality | 50 | 60 | 70 | 80 |
| AVIF quality | 48 | 51 | 56 | 64 |
| WEBP quality | 55 | 64 | 72 | 82 |
Compile
Install ImageMagick7 (with libheif/libjxl support) and MuPDF libraries and headers and then install to GOBIN:
go install -tags extlib github.com/gen2brain/cbconvert/cmd/cbconvert@latest
For GUI app, check IUP requirements, and then install:
go install -tags extlib github.com/gen2brain/cbconvert/cmd/cbconvert-gui@latest