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Watch imgp resize a directory of images in lightning speed!

imgp is a command line image resizer and rotator for JPEG and PNG images. It can resize (or thumbnail) and rotate thousands of images in a go, at lightning speed, while saving significantly on storage.

Powered by multiprocessing, SIMD parallelism (thanks to the Pillow-SIMD library), an intelligent adaptive algorithm, recursive operations, shell completion scripts, EXIF preservation (and more), imgp is a very flexible utility with well-documented easy to use options.

imgp intends to be a stronger replacement of the Nautilus Image Converter extension, not tied to any file manager and way faster. On desktop environments (like Xfce or LxQt) which do not integrate Nautilus, imgp will save your day. File manager nnn provides a script to batch resize images with imgp.


  • resize by percentage or resolution
  • rotate clockwise by specified angle
  • adaptive resize considering orientation
  • brute force to a resolution
  • optimize images to save more space
  • limit processing by minimum image size
  • convert PNG to JPEG
  • erase exif metadata
  • specify output JPEG image quality
  • force smaller to larger resize
  • process directories recursively
  • overwrite source image option
  • completion scripts for bash, fish, zsh
  • minimal dependencies

Adaptive mode

  • If the specified and image orientations are same [(H >= V and h > v) or (H < V and h < v)], the image is resized with the longer specified side as reference.
  • In case of cross orientation [(H >= V and h <= v) or (H < V and h >= v)], the image is resized with the shorter specified side as reference. Same as non-adaptive.

For example, if an image has a resolution of 2048×1365 and is being resized to 1366×768:

  • In regular mode (default), output image resolution will be 1152×768
  • In adaptive mode, output image resolution will be 1366×910


imgp could resize 8823 images (approx. 4.5GB in size) of mixed resolutions (high to regular) stored in a USB 2.0 external hard disk at an adaptive resolution of 1366×1000 in around 8 minutes. The resulting size was 897MB (approx. 20%).

imgp uses Python PIL/Pillow library. Nautilus Image Converter calls the convert utility from ImageMagick. For a comparative benchmark, head here.



imgp requires Python 3.6 or later.

To install PIL library on Ubuntu, run:

$ sudo apt-get install python3-pil

or, using pip3:

$ sudo pip3 install pillow

pillow can be replaced by pillow-simd on SIMD processors.

From a package manager

Install imgp from your package manager. If the version available is dated try an alternative installation method.

Packaging status (expand)

Packaging status

Unlisted packagers:

Homebrew TAP (brew install jarun/imgp/imgp)
PyPI (pip3 install imgp)
Source Mage (cast imgp)

Release packages

Packages for Arch Linux, CentOS, Debian, Fedora, openSUSE Leap and Ubuntu are available with the latest stable release.

From source

If you have git installed, clone this repository. Otherwise download the latest stable release or development version (risky).

Install to default location (/usr/local):

$ sudo make install

To remove, run:

$ sudo make uninstall

PREFIX is supported, in case you want to install to a different location.

Running standalone

imgp is a standalone utility. From the containing directory, run:

$ ./imgp

Shell completion

Shell completion scripts for Bash, Fish and Zsh can be found in respective subdirectories of auto-completion/. Please refer to your shell’s manual for installation instructions.


cmdline options

usage: imgp [-h] [-x res] [-o deg] [-a] [-c] [-e] [-f] [-H] [-i] [-k] [-m] [-M res]
            [-n] [-N] [-O] [-P] [-q N] [-r] [-s byte] [-w] [-d] [PATH [PATH ...]]

Resize, rotate JPEG and PNG images.

positional arguments:
  PATH                  source file or dir [default: current dir]

optional arguments:
  -h, --help            show this help message and exit
  -x res, --res res     output resolution in HxV or percentage
  -o deg, --rotate deg  rotate clockwise by angle (in degrees)
  -a, --adapt           adapt to resolution by orientation [default: off]
  -c, --convert         convert PNG to JPG format [default: off]
  -e, --eraseexif       erase exif metadata [default: off]
  -f, --force           force to exact specified resolution [default: off]
  -H, --hidden          include hidden (dot) files [default: off]
  -i, --includeimgp     re-process _IMGP files. * RISKY: refer to docs
  -k, --keep            skip (honors -c or --pr) images matching specified
                        H or V or --res=100 [default: off]
  -m, --mute            operate silently [default: informative]
  -M res, --minres res  min resolution in HxV or percentage of --res to resize
  -n, --enlarge         enlarge smaller images [default: off]
  -N, --nearest         use nearest neighbour interpolation for PNG [default: antialias]
  -O, --optimize        optimize the output images [default: off]
  -P, --progressive     save JPEG images as progressive [default: off]
  -q N, --quality N     quality factor (N=1-95, JPEG only) [default: 75]
  -r, --recurse         process non-symbolic dirs recursively [default: off]
  -s byte, --size byte  minimum size to process an image [default: 1024]
  -w, --overwrite       overwrite source images [default: off]
  -d, --debug           enable debug logs [default: off]

Operational notes

  • Multiple files and directories can be specified as source. If PATH is omitted, the current directory is processed.
  • Output image names are appended with _IMGP if --overwrite option is not used. By default _IMGP files are not processed. Doing so may lead to potential race conditions when --overwrite option is used.
  • PNG files with lower target hres/vres are not converted (even if --convert is used). Run imgp --convert (*.png) separately to convert those.
  • Resize and rotate are lossy operations. For additional reductions in size try --optimize and --eraseexif options.
  • Option --optimize is slower, the encoder makes an extra pass over the image in order to select optimal encoder settings.
  • Progressive JPEG images are saved as progressive.


  1. Convert some images and directories:

    11104999 bytes -> 1486426 bytes

    2048×1365 -> 1152×768
    224642 bytes -> 31421 bytes

    1920×1080 -> 1365×768
    2811155 bytes -> 1657474 bytes

    2048×1365 -> 1152×768
    224642 bytes -> 31421 bytes

    $ imgp -x 1366x768 ~/ ~/Pictures/image3.png ~/Downloads/
    3840x2160 -> 1365x768
    11104999 bytes -> 1486426 bytes
    2048x1365 -> 1152x768
    224642 bytes -> 31421 bytes
    1920x1080 -> 1365x768
    2811155 bytes -> 1657474 bytes
    2048x1365 -> 1152x768
    224642 bytes -> 31421 bytes
  2. Scale an image by 75% and overwrite the source image:

    120968 bytes -> 45040 bytes

    $ imgp -x 75 -w ~/image.jpg
    1366x767 -> 1025x575
    120968 bytes -> 45040 bytes
  3. Rotate an image clockwise by 90 degrees:

    72038 bytes

    $ imgp -o 90  ~/image.jpg
    120968 bytes -> 72038 bytes
  4. Adapt the images in the current directory to 1366×1000 resolution. Visit all directories recursively, overwrite source images, ignore images with matching hres or vres but convert PNG images to JPEG.

    $ imgp -x 1366x1000 -wrack
  5. Set hres=800 and adapt vres maintaining the ratio.

    69022 bytes -> 35123 bytes

    1050×1400 -> 800×1067
    458092 bytes -> 78089 bytes

    $ imgp -x 800x0
    Source omitted. Processing current directory...
    1366x911 -> 800x534
    69022 bytes -> 35123 bytes
    1050x1400 -> 800x1067
    458092 bytes -> 78089 bytes
  6. Process images greater than 50KiB only:

    $ imgp -wrackx 1366x1000 -s 51200
  7. Generate a 64px adapative thumbnail of the last modified file in the current dir:

    #!/usr/bin/env sh
    thumb64 ()
        pop=$(ls -1t | head -1)
        imgp -acx 64x64 "$pop"


  1. Copyright © 2016-2021
  2. Ananya Jana