jpegoptim

Optimise a set of JPEG images, retaining all associated data

$ jpegoptim [image1.jpeg image2.jpeg image3.jpeg ...]

$ jpegoptim [[-s|--strip-all]] [image1.jpeg image2.jpeg image3.jpeg ...]

$ jpegoptim --all-progressive [image1.jpeg image2.jpeg image3.jpeg ...]

$ jpegoptim [[-S|--size]] [250k] [image1.jpeg image2.jpeg image3.jpeg ...]

jpegoptim [options] filename(s)

-h, --help
    Display help information and exit.

-V, --version
    Output version information and exit.

-d, --dest=dir
    Specify a destination directory for optimized files. Original files remain untouched.

-f, --force
    Force optimization even if the file size does not decrease. Overwrites the original file by default.

-n, --noaction
    Do not actually optimize files; just print statistics. Useful for testing or previewing changes.

-m, --max=quality
    Set the maximum image quality factor (0-100, default: 95). Lower values result in smaller files but lower quality.

-s, --strip-all
    Strip all markers (comments, EXIF, IPTC, etc.) from the JPEG file, achieving maximum metadata removal.

-o, --overwrite
    Overwrite the source file with the optimized version (this is the default behavior).

-p, --preserve
    Preserve the original file modification times after optimization.

-t, --threshold=size
    Optimize only if the file size is reduced by at least the specified size (in kBytes).

-v, --verbose
    Enable verbose output, showing detailed statistics for each processed file.

-q, --quiet
    Enable quiet mode, suppressing most output messages.

-b, --bits=N
    Force the file to N bits. Useful for converting to progressive JPEG by forcing 8-bit output.

-P, --preserve-perms
    Preserve original file permissions after optimization.

-T, --csv
    Output optimization statistics in CSV (Comma Separated Values) format.

-D, --pedantic
    Do not ignore non-fatal errors during processing, leading to stricter error checking.

-X, --stdout
    Output the optimized image to standard output (implies --noaction).

-S, --size=size
    Try to optimize the file to a target size (e.g., '100K'). This may involve lossy compression.

-k, --keep-meta
    Keep all metadata (EXIF, IPTC, comments, ICC profile) during optimization. Overrides stripping options.

--all-normal
    Optimize all images to normal (baseline) JPEG/JFIF format.

--all-progressive
    Optimize all images to progressive JPEG/JFIF format, which allows images to load gradually.

--all-lossless
    Optimize all images losslessly (removes unneeded data without changing quality).

--strip-comments
    Strip only JPEG comments.

--strip-exif
    Strip only EXIF (Exchangeable Image File Format) markers.

--strip-iptc
    Strip only IPTC (International Press Telecommunications Council) markers.

--strip-icc
    Strip only ICC (International Color Consortium) profile.

--enable-gamma
    Enable gamma correction during processing.

--disable-gamma
    Disable gamma correction during processing.

--gamma-factor=factor
    Set the gamma factor (default: 2.2).

--json
    Output statistics in JSON format (implies --noaction).

--stdin
    Read image data from standard input (implies --stdout and --noaction).

--use-arithmetic
    Use arithmetic coding for JPEG compression (can sometimes yield smaller files but less widely supported).

--no-arithmetic
    Do not use arithmetic coding (default is usually Huffman).

--disable-dqt
    Disable DQT (Discrete Quantization Table) optimization.

--disable-cpi
    Disable CPI (conditional progressive encoding) optimization.

--strip-jfif
    Strip JFIF (JPEG File Interchange Format) header.

jpegoptim is a command-line utility designed for optimizing and compressing JPEG image files. It can perform both lossless and lossy optimizations.

Lossless optimization removes unnecessary metadata (like comments, EXIF, IPTC, ICC profiles) and applies Huffman table optimization without altering image quality. Lossy optimization, on the other hand, allows you to reduce the image quality factor to achieve significantly smaller file sizes, though this comes at the cost of some image fidelity. The tool is highly efficient and useful for web developers, photographers, or anyone needing to reduce the file size of large collections of JPEG images for faster loading, reduced storage, or better email attachment sizes. It supports various options to control the compression level, metadata stripping, preservation of file attributes, and batch processing.

• jpegoptim specifically works with JPEG files; it cannot process other image formats like PNG, GIF, or WebP.
• While lossless optimization is safe, using lossy compression (with -m or -S) permanently reduces image quality to achieve smaller file sizes. Once quality is reduced, it cannot be fully recovered.
• When optimizing a large number of files, it's advisable to test with -n (no action) first, or create backups before running the command to ensure desired results.
• The effectiveness of jpegoptim might vary depending on the original JPEG file's quality and how it was saved. Heavily optimized JPEGs might see little further reduction.

jpegoptim is particularly effective for batch processing directories full of JPEG images, often combined with commands like find or xargs to automate optimization tasks across many files.

Users should understand the distinction between lossless optimizations (which preserve visual quality by removing unneeded data) and lossy optimizations (which reduce quality for greater file size reduction), choosing the appropriate mode based on their needs.

jpegoptim was created by Simon Peter. It has been developed and maintained over the years as a reliable tool for optimizing JPEG images, often included in Linux distributions' official repositories. Its focus on efficiency and straightforward command-line usage has made it a popular choice for scripting and automated image processing workflows.

optipng(1), pngcrush(1), gifsicle(1), cjpeg(1), djpeg(1), convert(1)