Image quality when saving - no loss to the human eye

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Bosrmak
Posts: 16
Joined: Tue Nov 14, 2023 4:33 pm

Image quality when saving - no loss to the human eye

Post by Bosrmak »

Good morning, when saving a photo in JPG format - you can choose its compression (quality). 100% means no losses. However, I have a question - up to what compression level is the difference invisible to the human eye?

I initially set the compression to 80% - will this be the threshold of noticeability for humans - cutting off some details - or not yet?

What I mean is that there will be no deterioration of image quality in relation to keeping its file size as small as possible.
Classic las version of XnView
cday
XnThusiast
Posts: 4003
Joined: Sun Apr 29, 2012 9:45 am
Location: Cheltenham, U.K.

Re: Image quality when saving - no loss to the human eye

Post by cday »

Bosrmak wrote: Thu Nov 16, 2023 9:35 am Good morning, when saving a photo in JPG format - you can choose its compression (quality). 100% means no losses.
I'm not sure that is actually the case... :?:
However, I have a question - up to what compression level is the difference invisible to the human eye?
There are many posts on the forum going back a long way on that topic, if you use the forum search option at top-right and select the gear option for a Google search within the forum, and particularly include the term 'xntriq' in the search, you should find much useful discussion... :D
I initially set the compression to 80% - will this be the threshold of noticeability for humans - cutting off some details - or not yet?
That is often a reasonable compromise for many situations, but many factors can be relevant such as the required final quality depending on how the images will be used. Also, in my experience, when filesize is important as in a large archive, images with large pixel dimensions can often be compressed with surprising high compression setting without very obvious loss of quality.
Bosrmak
Posts: 16
Joined: Tue Nov 14, 2023 4:33 pm

Re: Image quality when saving - no loss to the human eye

Post by Bosrmak »

Your comment made me want to run tests with different image compressions and sizes. To see what will be the best choice. Thank you for your help.
Classic las version of XnView