jimp-dev/jimp

Can Jimp write a jpg file which exactly have the same color which I set?

Open

#685 opened on Dec 31, 2018

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

Description

Expected Behavior

I used setPixelColor to operate the color of each pixels.

I used this to save the jpg file:

picture.quality(100).writeAsync(path);

I wish that Jimp can write a jpg file which exactly have the same color which I set.

Current Behavior

When I used getPixelColor to read the saved jpg, I found that the colors are a little bit different with what I operated.

But this seems only effected with saving jpg.

After I saved the picture as bmp, I read the bmp file. I got the colors I wanted.

Steps to Reproduce

  1. Use Jimp.read to read the jpg file.
  2. Use setPixelColor to edit a color of a pixel.
  3. Use quality(100).writeAsync to save the file as a new jpg.
  4. Use Jimp.read to read the new jpg file.
  5. Use getPixelColor to get the color which I edited.
  6. Compare the color with what I set before.
  7. They are different a little.

Context

  • Jimp Version: 0.6.0
  • Operating System: Windows 10 Pro 64bit
  • Node version: 111.6.0

So, may I save the color into jpg strictly as what I want?

Thank you for checking this.

Failure Logs

Nope.

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
needs maintainer response
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with JavaScriptUnderstanding of JPEG lossy compression
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate whether Jimp's JPEG encoder supports lossless compression or if color shifts are inherent. Check the write method in the Jimp source code (e.g., /packages/jimp/src/index.js) and review the README for image format limitations. If lossless JPEG is not supported, propose adding a documentation entry explaining that JPEG is a lossy format and colors may differ slightly from what was set. Reference similar issues or comments in the repository.