# Changing the brightness of purple stimuli

**URL:** <https://psychtoolbox.discourse.group/t/changing-the-brightness-of-purple-stimuli/611>\
**Category:** Uncategorized\
**Created:** [October 24, 2009, 12:42pm UTC](https://psychtoolbox.discourse.group/t/changing-the-brightness-of-purple-stimuli/611 "2009-10-24T12:42:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [October 24, 2009, 12:42pm UTC](https://psychtoolbox.discourse.group/t/changing-the-brightness-of-purple-stimuli/611/1 "2009-10-24T12:42:30Z")

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Dear all,  
  
I'm new to psychtoolbox and MATLAB in general so forgive the simple question. What I would like to do is make purple lines of the same brightness as the background (medium gray). My program will display the purple lines, but how can I make them lighter or darker?  
  
Thanks,  
Elaina