Cleaning metadata affecting image quality?

[Xavier.png]

Hello!

I have recently scrubbed all my images (mostly JPG's) of metadata using the feature under 'tools > metadata > clean' in the browser. It all went smoothly, but after the operation, I noticed that all my files had a smaller file size than before. Between 5 - 25KB less, on average. Now, I'm afraid that cleaning the metadata somehow has affected the quality of my images. I checked again and again, but did not find a single difference in quality, but I'm still a bit worried about it.

After looking around on the forums, I think I don't have to be worried. But I could not find a definite answer to this. Could anyone explain to me how the cleaning tool works and should I be worried about it affecting my image quality?

Thanks in advance

[Xavier.png]

I understand it’s a bit of a simple question that might easily be looked up, but the answer depends on how the cleaning tool in XnviewMP works. An answer or even a link to something would be very helpful!

[michel038]

As far as I know, XnViewMP reads/writes only headers of jpg pictures when working on metadata
Decoding /coding the picture is not needed

If metadata are cleaned, obviously the size of the file decreases ...

[XnTriq]

Optimize Huffman table also reduces file size.

The three types of JPEG are Baseline, Baseline Optimized, and Progressive.

• Baseline (Standard)
  All web browsers recognize this JPEG format.
• Baseline Optimized
  This JPEG format option provides an optimized color and slightly better compression. All modern browsers support it, but earlier ones didn't. It's your best choice for JPEG files today.
• Progressive
  Creates a JPEG file that displays as it downloads, starting blocky, and getting progressively clearer as it downloads. It doesn't make the image download any faster, but it can give the illusion of speed since the blocky image loads right away on a slow connection. With the majority of internet users on high-speed connections today, Progressive JPEG is rarely used.

• RIOT – Radical Image Optimization Tool
  • JPEG Optimization
• ImpulseAdventure
  • JPEG Huffman Coding Tutorial
  • What is an Optimized JPEG?
• YUIBlog
  • Progressive JPEG… Hot or Not?
• XnView Forum
  • progressive to baseline jpeg
  • More explanations for simple users
  • JPEG Lossless question. Why is the file size smaller?
  • Cleaning Metadata Without Altering Image
  • Clean Metadata re-encodes JPEGs?
  • Basic understanding of "JPEG Quality"?