Author Topic: How to create mask from luminance data ? (Read 833 times)

rs.sowa · **on:** April 22, 2019, 11:01:34 am

Hello guys.
I'm new to Designer but recently i wanted to create filter. Something similar to PBR Validation tool but im strugling with creating mask that is made from luminence values. I want to make a gradient from one color to another which depends on luminence values i take from input node. how to achive that ?
For eg. I want that one color will start gradient from 35 luminence value and end on 85 with different color.

michael_11 · **Reply #1 on:** April 22, 2019, 06:05:38 pm

did you try using a histogram scan or histogram range node?

rs.sowa · **Reply #2 on:** April 24, 2019, 09:20:32 pm

But how can i get luminence values into another node or any function. I suspect it can be done in many ways but i can't figure out how to get only V from HSV in base color input node. It drive me crazy because it is (i think) so simple and i can't make it.

divi.cig · **Reply #3 on:** April 25, 2019, 07:29:06 am

inside a pixel processor

michael_11 · **Reply #4 on:** April 27, 2019, 01:03:05 pm

isn´t the luminance value just the (desaturated) grayscale value of an image?

divi.cig · **Reply #5 on:** May 14, 2019, 12:39:08 pm

Quote from: michael_11 on April 27, 2019, 01:03:05 pm

isn´t the luminance value just the (desaturated) grayscale value of an image?

if it's a greyscale image, yes.

for color images it isn't.

michael_11 · **Reply #6 on:** May 16, 2019, 09:28:43 am

interesting, I had no idea

http://www.workwithcolor.com/color-luminance-2233.htm

michael_11 · **Reply #7 on:** May 16, 2019, 09:31:36 am

to better illustrate my misconception, I am adding a grayscale version of the previous image: