JPEG Archive

Utilities for archiving photos for saving to long term storage or serving over the web. The goals are:

Use a common, well supported format (JPEG)
Minimize storage space and cost
Identify duplicates / similar photos

Approach:

Command line utilities and scripts
Simple options and useful help
Good quality output via sane defaults

Contributions to this project are very welcome.

Download

You can download the latest source and binary releases from the JPEG Archive releases page. Windows binaries for the latest commit are available from the Windows CI build server.

If you are looking for an easy way to run these utilities in parallel over many files to utilize all CPU cores, please also download Ladon or GNU Parallel. You can then use the jpeg-archive command below or use ladon directly. Example:

# Re-compress JPEGs and replace the originals
ladon "Photos/**/*.jpg" -- jpeg-recompress FULLPATH FULLPATH

# Re-compress JPEGs into the new directory 'Comp'
ladon -m Comp/RELDIR "Photos/**/*.jpg" -- jpeg-recompress FULLPATH Comp/RELPATH

Utilities

The following utilities are part of this project. All of them accept a --help parameter to see the available options.

jpeg-archive

Compress RAW and JPEG files in a folder utilizing all CPU cores. This is a simple shell script that uses the utilities below. It requires:

a POSIX-compatible shell such as Bash
Ladon or GNU Parallel
dcraw
exiftool
jpeg-recompress (part of this project)

# Compress a folder of images
cd path/to/photos
jpeg-archive

# Custom quality and metric
jpeg-archive --quality medium --method smallfry

jpeg-recompress

Compress JPEGs by re-encoding to the smallest JPEG quality while keeping perceived visual quality the same and by making sure huffman tables are optimized. This is a lossy operation, but the images are visually identical and it usually saves 30-70% of the size for JPEGs coming from a digital camera, particularly DSLRs. By default all EXIF/IPTC/XMP and color profile metadata is copied over, but this can be disabled to save more space if desired.

There is no need for the input file to be a JPEG. In fact, you can use jpeg-recompress as a replacement for cjpeg by using PPM input and the --ppm option.

The better the quality of the input image is, the better the output will be.

Some basic photo-related editing options are available, such as removing fisheye lens distortion.

Demo

Below are two 100% crops of Nikon's D3x Sample Image 2. The left shows the original image from the camera, while the others show the output of jpeg-recompress with the medium quality setting and various comparison methods. By default SSIM is used, which lowers the file size by 88%. The recompression algorithm chooses a JPEG quality of 80. By comparison the veryhigh quality setting chooses a JPEG quality of 93 and saves 70% of the file size.

Why are they different sizes? The default quality settings are set to average out to similar visual quality over large data sets. They may differ on individual photos (like above) because each metric considers different parts of the image to be more or less important for compression.

Image Comparison Metrics

The following metrics are available when using jpeg-recompress. SSIM is the default.

Name	Option	Description
MPE	`-m mpe`	Mean pixel error (as used by imgmin)
SSIM	`-m ssim`	Structural similarity DEFAULT
MS-SSIM*	`-m ms-ssim`	Multi-scale structural similarity (slow!) (2008 paper)
SmallFry	`-m smallfry`	Linear-weighted BBCQ-like (original project, 2011 BBCQ paper)

Note: The SmallFry algorithm may be patented so use with caution.

Subsampling

The JPEG format allows for subsampling of the color channels to save space. For each 2x2 block of pixels per color channel (four pixels total) it can store four pixels (all of them), two pixels or a single pixel. By default, the JPEG encoder subsamples the non-luma channels to two pixels (often referred to as 4:2:0 subsampling). Most digital cameras do the same because of limitations in the human eye. This may lead to unintended behavior for specific use cases (see #12 for an example), so you can use --subsample disable to disable this subsampling.

Example Commands

# Default settings
jpeg-recompress image.jpg compressed.jpg

# High quality example settings
jpeg-recompress --quality high --min 60 image.jpg compressed.jpg

# Slow high quality settings (3-4x slower than above, slightly more accurate)
jpeg-recompress --accurate --quality high --min 60 image.jpg compressed.jpg

# Use SmallFry instead of SSIM
jpeg-recompress --method smallfry image.jpg compressed.jpg

# Use 4:4:4 sampling (disables subsampling).
jpeg-recompress --subsample disable image.jpg compressed.jpg

# Remove fisheye distortion (Tokina 10-17mm on APS-C @ 10mm)
jpeg-recompress --defish 2.6 --zoom 1.2 image.jpg defished.jpg

# Read from stdin and write to stdout with '-' as the filename
jpeg-recompress - - <image.jpg >compressed.jpg

# Convert RAW to JPEG via PPM from stdin
dcraw -w -q 3 -c IMG_1234.CR2 | jpeg-recompress --ppm - compressed.jpg

# Disable progressive mode (not recommended)
jpeg-recompress --no-progressive image.jpg compressed.jpg

# Disable all output except for errors
jpeg-recompress --quiet image.jpg compressed.jpg

jpeg-compare

Compare two JPEG photos to judge how similar they are. The fast comparison method returns an integer from 0 to 99, where 0 is identical. PSNR, SSIM, and MS-SSIM return floats but require images to be the same dimensions.

# Do a fast compare of two images
jpeg-compare image1.jpg image2.jpg

# Calculate PSNR
jpeg-compare --method psnr image1.jpg image2.jpg

# Calculate SSIM
jpeg-compare --method ssim image1.jpg image2.jpg

jpeg-hash

Create a hash of an image that can be used to compare it to other images quickly.

jpeg-hash image.jpg

Building

Dependencies

mozjpeg

Ubuntu

Ubuntu users can install via apt-get:

sudo apt-get install build-essential autoconf pkg-config nasm libtool
git clone https://github.com/mozilla/mozjpeg.git
cd mozjpeg
autoreconf -fiv
./configure --with-jpeg8
make
sudo make install

Mac OS X

Mac users can install it via Homebrew:

brew install mozjpeg

FreeBSD

pkg install mozjpeg
git clone https://github.com/danielgtaylor/jpeg-archive.git
cd jpeg-archive/
gmake
sudo gmake install

Windows

The Makefile should work with MinGW/Cygwin/etc and standard GCC. Patches welcome.

To get everything you need to build, install these:

CMake
NASM
MinGW (installed to e.g. C:\mingw)
Github for Windows

Run Github for windows. In the settings, set Git Bash as the shell. Open Git Shell from the start menu.

# Update PATH to include MinGW/NASM bin folder, location on your system may vary
export PATH=$PATH:/c/mingw/mingw32/bin:/c/Program\ Files \(x68\)/nasm

# Build mozjpeg or download https://www.dropbox.com/s/98jppfgds2xjblu/libjpeg.a
git clone https://github.com/mozilla/mozjpeg.git
cd mozjpeg
cmake -G "MSYS Makefiles" -D CMAKE_C_COMPILER=/c/mingw/bin/gcc.exe -D CMAKE_MAKE_PROGRAM=/c/mingw/bin/mingw32-make.exe  -DWITH_JPEG8=1 .
mingw32-make
cd ..

# Build jpeg-archive
git clone https://github.com/danielgtaylor/jpeg-archive
cd jpeg-archive
CC=gcc mingw32-make

JPEG-Archive should now be built.

Compiling (Linux and Mac OS X)

The Makefile should work as-is on Ubuntu and Mac OS X. Other platforms may need to set the location of libjpeg.a or make other tweaks.

make

Installation

Install the binaries into /usr/local/bin:

sudo make install

Links / Alternatives

License

Image Quality Assessment (IQA) is copyright 2011, Tom Distler (http://tdistler.com)

All are released under an MIT license.

http://dgt.mit-license.org/

jlebar / jpeg-archive