What do automatic contrast and levels do?

Ask for help and post your question on how to use XnView MP.

Moderators: XnTriq, xnview

Post Reply
lucmv
Posts: 14
Joined: Sun Dec 06, 2015 7:42 pm

What do automatic contrast and levels do?

Post by lucmv » Fri Feb 01, 2019 12:46 am

I use these two commands — automatic contrast and automatic levels — to improve photos. I usually like the results. Sometimes, not often, they seem to have no effect at all.

Would someone be so kind to explain what exactly those two commands do? No, their names are not self explanatory, at least not to me. I would love to get a deeper insight on what they do.

Anyone?

TIA

User avatar
xnview
Author of XnView
Posts: 30627
Joined: Mon Oct 13, 2003 7:31 am
Location: France
Contact:

Re: What do automatic contrast and levels do?

Post by xnview » Mon Feb 04, 2019 11:46 am

'Auto levels' try to expand the histogram of intensity
'Auto contrast' apply brightness/contrast following histogram
Pierre.

mobi
Posts: 3
Joined: Wed Feb 06, 2019 2:12 pm

Re: What do automatic contrast and levels do?

Post by mobi » Wed Feb 06, 2019 2:16 pm

Where do I find this auto level/contrast option? :|

User avatar
xnview
Author of XnView
Posts: 30627
Joined: Mon Oct 13, 2003 7:31 am
Location: France
Contact:

Re: What do automatic contrast and levels do?

Post by xnview » Wed Feb 06, 2019 3:13 pm

mobi wrote:
Wed Feb 06, 2019 2:16 pm
Where do I find this auto level/contrast option? :|
Edit mode
Pierre.

Post Reply