Smally

• How to Compress
  • JPEG
  • PNG
  • GIF
• How to Install
• How to Use
• APIs
• Showcase

Smally is a simple tool to compress JPEG, PNG and GIF files losslessly, by invoking the famous jpegtran, optipng and gifsicle tools, in batch mode, in-place and keep mtime unchanged. It is written in Python, but heavily rely on shell.

How to Compress

JPEG

1. Using jpegtran to remove all metadata, create a baseline version and a progressive version.
2. To compare among the original file, baseline and progressive files, choose the smallest one in size.
3. Whenever possible, choose progressive version.

PNG

Calling optipng to compress PNG, in the most crazy -o7 -zm1-9 level.

GIF

Calling gifsicle to compress GIF, by using -O3 --color 256.

How to Install

# install tools on Fedora
$ sudo dnf install libjpeg-turbo-utils optipng gifsicle
# install tools on Ubuntu
$ sudo apt install libjpeg-turbo-progs optipng gifsicle
# install smally
$ pip install smally

How to Use

# inline help
$ python -m smally -h
# to compress a single file, if option is not presented,
# smally will use file command to get file type info.
$ python -m smally [-j|-p|-g] <pathname>
# to compress a directory
$ python -m smally -r -P<N> <pathname>
# to compress all png file in a directory
$ python -m smally -r -P<N> -p <pathname>

-r, recursively, it's a command line convention and normally you should use it when deal with a directory.

-P<N>, parallel process number, if it is missing, the logical cpu count number will be used.

APIs

4 APIs provided by smally:

# import
from smally import (jpegtran,
                    optipng,
                    gifsicle,
                    is_jpeg_progressive)
# signature
def jpegtran(pathname: str) -> tuple[int,int]: ...
def optipng(pathname: str) -> tuple[int,int]: ...
def gifsicle(pathname: str) -> tuple[int,int]: ...
def is_jpeg_progressive(pathname: str) -> bool: ...

The first int in returned tuple is the byte number saved. It could be zero, which means no save. The second int is the original file size.

Showcase

$ python -m smally -r smally/tpic -P4
# parallel process number:  4
smally/tpic/102.jpg -24157 -16.38% [p]
smally/tpic/302.gif -333056 -19.67%
smally/tpic/testpic/302.gif -333056 -19.67%
smally/tpic/testpic/102.jpg -24157 -16.38% [p]
smally/tpic/201.png -548 -26.37%
smally/tpic/testpic/201.png -548 -26.37%
smally/tpic/testpic/testpic/102.jpg -24157 -16.38% [p]
smally/tpic/testpic/testpic/302.gif -333056 -19.67%
smally/tpic/testpic/testpic/201.png -548 -26.37%