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, DOCX, PPTX 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 or grayscale images
• resize filters (NearestNeighbor, Box, Linear, MitchellNetravali, CatmullRom, Gaussian, Lanczos)
• export covers from comics
• create thumbnails from covers by FreeDesktop specification

Download

Download the latest binaries from the releases.

Linux Flatpak is available at Flathub.

Compile

You must have CGO_ENABLED=1. Note that Go will disable cgo when cross-compiling.

Install to GOBIN (you can point GOBIN to e.g. /usr/local/bin or ~/.local/bin):

go install github.com/gen2brain/cbconvert/cmd/cbconvert@latest

For GUI app, check IUP requirements, and then install:

go install github.com/gen2brain/cbconvert/cmd/cbconvert-gui@latest

Build tags

• extlib - use external libmupdf and libunarr libraries
• pkgconfig - enable pkg-config (used with extlib)

Using cbconvert in file managers to generate FreeDesktop thumbnails

Copy/install cbconvert cli binary to your PATH, create file ~/.local/share/thumbnailers/cbconvert.thumbnailer and paste contents from thumbnailer.

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 "")
    --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 (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 from archive (glob pattern, i.e. *.xml) (default "")

  version
        Print version

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: