jimp-dev/jimp

Setting lower quality increases the file size

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#1018 opened on Jun 2, 2021

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 (0 comments) (0 reactions) (0 assignees)JavaScript (13,218 stars) (785 forks)batch import
bugfile size issuehelp wanted

Description

Expected Behavior

Decrease the file size with decrement in image quality.

Current Behavior

Increase the file size with decrement in image quality.

Code

jimp.read("./forest-patrol.jpg", (err, lenna) => {
  if (err) throw err;
  lenna
    .quality(60) // set JPEG quality
    .write("./forest-patrol-jimp-mini.jpg"); // save
});

bug-report Here, we can see that original image forest-patrol.jpg is smaller than the processed image forest-patrol-jimp.jpg

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Node.jsJimp APIBasic understanding of JPEG compression
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate why setting a lower JPEG quality (e.g., 60) results in a larger file size than the original. Start by examining the `quality` method in Jimp's JPEG plugin (likely in `/packages/plugin jpeg/src/index.js`). Check if the quality parameter is passed correctly to the underlying JPEG encoder. Compare the encoded buffer sizes at different quality levels. Look for any existing issues or PRs related to JPEG compression in the repository.