jpegtran

performs lossless transformations on JPEG images

TLDR

Mirror an image horizontally or vertically

$ jpegtran -flip [horizontal|vertical] [path/to/image.jpg] > [path/to/output.jpg]

Rotate an image 90, 180, or 270 degrees clockwise

$ jpegtran -rotate [90|180|270] [path/to/image.jpg] > [path/to/output.jpg]

Transpose across upper-left to lower-right axis

$ jpegtran -transpose [path/to/image.jpg] > [path/to/output.jpg]

Convert to grayscale

$ jpegtran -grayscale [path/to/image.jpg] > [path/to/output.jpg]

Crop to specified dimensions

$ jpegtran -crop [W]x[H]+[X]+[Y] [path/to/image.jpg] > [path/to/output.jpg]

Crop and save to specific file

$ jpegtran -crop [W]x[H] -outfile [path/to/output.jpg] [path/to/image.jpg]

jpegtran performs lossless transformations on JPEG images. Unlike re-encoding, these operations work directly on the DCT coefficients, preserving image quality completely.Supported lossless operations include rotation (in 90-degree increments), flipping, transposition, grayscale conversion, and cropping (on MCU boundaries). The tool can also optimize or convert between baseline and progressive formats.

PARAMETERS

-flip horizontal|vertical

Mirror the image

-rotate 90|180|270

Rotate clockwise by specified degrees

-transpose

Transpose across main diagonal

-transverse

Transpose across anti-diagonal

-grayscale

Convert to grayscale

-crop WxH+X+Y

Crop to width W, height H, at offset X,Y

-outfile FILE

Write output to specified file

-optimize

Optimize Huffman tables

-progressive

Create progressive JPEG

INSTALL

sudo apt install libjpeg-turbo-progs

sudo dnf install libjpeg-turbo-utils

sudo apk add libjpeg-turbo-utils

CAVEATS

Crop dimensions may be adjusted to MCU (Minimum Coded Unit) boundaries. Some transformations may require -trim to discard partial edge blocks. Output goes to stdout by default; redirect or use -outfile.

HISTORY

jpegtran is part of libjpeg/libjpeg-turbo, the reference JPEG library. The original libjpeg was developed by the Independent JPEG Group starting in 1991.