jpegtran — Transform and Optimize JPEG Files Losslessly

jpegtran transforms JPEG images entirely losslessly – without ever re-decoding and re-encoding them. Instead of re-rendering the picture, the tool rearranges the already-compressed DCT blocks directly: you rotate, flip, crop or optimize a file without losing a single extra bit of quality. That makes jpegtran the go-to choice when you want to slim down photos for the web or fix their orientation without introducing visible artifacts.

Optimization

jpegtran -optimize <input.jpg> > <output.jpg> — Optimize Huffman coding tables (smaller file, no quality loss).

jpegtran -optimize photo.jpg > optimized.jpg

jpegtran -progressive <input.jpg> > <output.jpg> — Convert to progressive JPEG (better for web, loads gradually).

jpegtran -progressive photo.jpg > progressive.jpg

jpegtran -optimize -progressive <input.jpg> > <output.jpg> — Optimize and convert to progressive (best lossless compression).

jpegtran -optimize -progressive photo.jpg > optimized.jpg

jpegtran -copy none -optimize -progressive <input.jpg> > <output.jpg> — Optimize, make progressive, and strip all metadata.

jpegtran -copy none -optimize -progressive photo.jpg > clean.jpg

jpegtran -arithmetic <input.jpg> > <output.jpg> — Use arithmetic coding (smaller files, limited browser support).

jpegtran -arithmetic photo.jpg > arithmetic.jpg

Rotation (Lossless)

jpegtran -rotate 90 <input.jpg> > <output.jpg> — Rotate 90 degrees clockwise (lossless).

jpegtran -rotate 90 photo.jpg > rotated.jpg

jpegtran -rotate 180 <input.jpg> > <output.jpg> — Rotate 180 degrees (lossless).

jpegtran -rotate 180 photo.jpg > rotated.jpg

jpegtran -rotate 270 <input.jpg> > <output.jpg> — Rotate 270 degrees / 90 counter-clockwise (lossless).

jpegtran -rotate 270 photo.jpg > rotated.jpg

jpegtran -rotate 90 -trim <input.jpg> > <output.jpg> — Rotate and trim partial MCU blocks at edges (avoids green edge artifacts).

jpegtran -rotate 90 -trim photo.jpg > rotated.jpg

jpegtran -rotate 90 -perfect <input.jpg> > <output.jpg> — Rotate only if it can be done perfectly (fail if dimensions not MCU-aligned).

jpegtran -rotate 90 -perfect photo.jpg > rotated.jpg

Flip (Lossless)

jpegtran -flip horizontal <input.jpg> > <output.jpg> — Mirror horizontally (lossless).

jpegtran -flip horizontal photo.jpg > mirrored.jpg

jpegtran -flip vertical <input.jpg> > <output.jpg> — Mirror vertically (lossless).

jpegtran -flip vertical photo.jpg > flipped.jpg

jpegtran -transpose <input.jpg> > <output.jpg> — Transpose (mirror along top-left to bottom-right diagonal).

jpegtran -transpose photo.jpg > transposed.jpg

jpegtran -transverse <input.jpg> > <output.jpg> — Transverse (mirror along top-right to bottom-left diagonal).

jpegtran -transverse photo.jpg > transversed.jpg

Crop (Lossless)

jpegtran -crop <width>x<height>+<x>+<y> <input.jpg> > <output.jpg> — Crop a region (coordinates must align to MCU boundaries, usually 8px or 16px).

jpegtran -crop 640x480+0+0 photo.jpg > cropped.jpg

jpegtran -crop <width>x<height> <input.jpg> > <output.jpg> — Crop from the top-left corner.

jpegtran -crop 800x600 photo.jpg > cropped.jpg

jpegtran -crop <width>x<height>+<x>+<y> -trim <input.jpg> > <output.jpg> — Crop with trimming to align to MCU boundaries.

jpegtran -crop 500x400+100+50 -trim photo.jpg > cropped.jpg

jpegtran -drop +<x>+<y> <overlay.jpg> <input.jpg> > <output.jpg> — Drop (overlay) another JPEG at a position (lossless splice).

jpegtran -drop +0+0 watermark.jpg photo.jpg > watermarked.jpg

Metadata Control

jpegtran -copy none <input.jpg> > <output.jpg> — Strip all metadata (EXIF, comments, ICC profiles).

jpegtran -copy none photo.jpg > stripped.jpg

jpegtran -copy comments <input.jpg> > <output.jpg> — Keep only comment markers (jpegtran's default), remove EXIF and other markers.

jpegtran -copy comments photo.jpg > clean.jpg

jpegtran -copy all <input.jpg> > <output.jpg> — Preserve all extra markers, including EXIF, ICC profile and thumbnails.

jpegtran -copy all photo.jpg > output.jpg

jpegtran -copy icc <input.jpg> > <output.jpg> — Keep only ICC color profile, strip EXIF and comments.

jpegtran -copy icc photo.jpg > color-preserved.jpg

Grayscale & Color

jpegtran -grayscale <input.jpg> > <output.jpg> — Convert to grayscale (lossless, removes chroma channels).

jpegtran -grayscale photo.jpg > grayscale.jpg

jpegtran -grayscale -optimize <input.jpg> > <output.jpg> — Convert to grayscale and optimize (significant size reduction).

jpegtran -grayscale -optimize photo.jpg > bw-optimized.jpg

Common Patterns

for f in *.jpg; do jpegtran -copy none -optimize -progressive "$f" > "opt-$f"; done — Batch optimize all JPEGs in a directory.

for f in *.jpg; do jpegtran -copy none -optimize -progressive "$f" > "opt-$f"; done

find . -name '*.jpg' -exec sh -c 'jpegtran -copy none -optimize -progressive "$1" > "$1.tmp" && mv "$1.tmp" "$1"' _ {} \; — Recursively optimize all JPEGs in-place.

find . -name '*.jpg' -exec sh -c 'jpegtran -copy none -optimize -progressive "$1" > "$1.tmp" && mv "$1.tmp" "$1"' _ {} \;

jpegtran -rotate 90 -copy all -optimize photo.jpg > rotated.jpg — Lossless rotate while preserving metadata and optimizing.

jpegtran -rotate 90 -copy all -optimize photo.jpg > rotated.jpg

jpegtran -copy none -optimize -progressive -outfile <output.jpg> <input.jpg> — Use -outfile flag instead of stdout redirection.

jpegtran -copy none -optimize -progressive -outfile optimized.jpg photo.jpg

Conclusion

jpegtran shines whenever every bit of quality matters: optimizing, rotating, flipping and cropping all run entirely losslessly, straight on the compressed data. Keep two things in mind, though. First, -copy none strips all metadata – including the EXIF orientation tag and the embedded ICC color profile; with smartphone photos in particular, the result can end up sideways or color-shifted. Use -copy all to keep those markers (the default -copy comments retains only comments). Second, lossless rotation only works cleanly when the image dimensions are divisible by the MCU size (8 or 16 pixels) – otherwise reach for -perfect (which aborts rather than rotating imperfectly) or -trim (which discards the incomplete edge blocks). And don't forget: jpegtran does not work in place but writes its result to stdout or via -outfile – redirect it to a different file, or you risk overwriting your original.