PNG to JPEG via CLI

Convert PNG to JPEG with ffmpeg and a quality setting.

Packages to install

Install ffmpeg — one command re-encodes PNG to JPEG.

ffmpeg

sudo apt-get update
sudo apt-get install -y ffmpeg

How to run the command

Pass the PNG to -i and set JPEG quality with -q:v: lower is better (2 is near-lossless, 5–8 is smaller).

ffmpeg -y -i photo.png -q:v 2 photo.jpg

Dockerfile example

Build a minimal Ubuntu image with the required packages and run the conversion inside the container.

FROM ubuntu:24.04

RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        ffmpeg && \
    rm -rf /var/lib/apt/lists/*

WORKDIR /work

docker build -t png-to-jpeg .
docker run --rm -v "$PWD:/work" -w /work png-to-jpeg \
  ffmpeg -y -i photo.png -q:v 2 photo.jpg

Example commands

Run these locally after installing the packages, or inside the container from the Dockerfile.

ffmpeg -y -i photo.png -q:v 2 photo.jpg

ffmpeg -y -i photo.png -q:v 5 photo.jpeg