jimp-dev/jimp

Convert BMP to JPG and resulted image has incorrect color

Open

#975 opened on Jan 5, 2021

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

Description

Expected Behavior

The converted JPG image should maintain the same color scheme.

Current Behavior

The colors of the converted JPG image fall in the red spectrum

Failure Information (for bugs)

Screenshots

Original image original-image

Outputted image lena-small-bw4-1609828096077

Steps to Reproduce

  • Jimp Version: 0.16.1
  • Operating System: Unbuntu
  • Node version: v10.18.1

Failure Logs

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.js basicsBMP/JPG color handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Examine the BMP decoder in Jimp's source code to verify that pixel data is being read in the correct byte order. BMP files store pixels in BGR format, while JPG expects RGB. Check if there is a color conversion step. Reproduce the bug using the provided code and add debugging to log the pixel values before and after reading the BMP. Look for any existing tests for BMP to JPG conversion to understand expected behavior. Consider if the issue is specific to certain BMP images (e.g., those generated by online convert.com).