PixInsight Forum

PixInsight => Tutorials and Processing Examples => Topic started by: Robert-Poelzl on 2012 December 03 13:01:39

Title: Smal values in Histogram Transformation Tool
Post by: Robert-Poelzl on 2012 December 03 13:01:39
Hello friends

This is my first image and i hope that i can get a little help from the group.
I m makeing astrofotography for 5 years and my workflow was ccd stack and Ps.
My english is not the best, so i hope that anybody can understand my questions  :sealed:

I visited this onlinetutorial http:// ...
 
To get a little training i opened an older picture (16bit tiff) and wonder about the little values in the histogram transformation tool.

What can be the reason for it??
I selected 16 bit - when i change to 8 bit the values looks good  - but that would be wrong.

Thanks for help.
kind regards
Robert
www.astrofotos.at

*** Edited to remove link to restricted access site.
Title: Re: Smal values in Histogram Transformation Tool
Post by: Nocturnal on 2012 December 03 13:23:00

Hi,

the 16b selector tells PI to use 64k buckets for the histogram. Pixel values are almost always normalized between 0 and 1. If Warren did not explain that in his tutorials I think you may want to ask about that :-)

Next time please post screenshots with full color resolution. Right now it looks a bit odd.
Title: Re: Smal values in Histogram Transformation Tool
Post by: pproulx on 2013 January 02 18:56:01
Robert - Please delete your post as it is a link for a paid access site.

Thank you;

Peter IP4AP.com
Title: Re: Smal values in Histogram Transformation Tool
Post by: Warhen on 2013 January 30 09:50:17
Robert, The intricacies of the HT tool will be covered in IP4AP's PI Part-2's tutorials. PI-1 concentrated on the user interface, stacking, and linear processing. As we cross into nonlinear, this and many other tools will be highlighted. Thanks- hey Sander!!
Title: Re: Smal values in Histogram Transformation Tool
Post by: Geoff on 2013 January 30 13:31:33
Hi Robert
Check out these videos http://www.harrysastroshed.com/pixinsighthomenewbie.html
You'll find details on the histogram stretch there. 
Geoff