Public Lab Research note

Color perception: influence of an different colored object

by Joeri2 | December 31, 2014 02:53 | 22 views | 2 comments | #11501 | 22 views | 2 comments | #11501 31 Dec 02:53

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What I want to do

I use the spectrometer as a relative reflectance spectrometer to measure the change in color when a 3d-object is placed in front of a card. The question is how will an object with a different color than a painted surface influence the perception of color. I don't have the time to fully research this, but I will try to measure a difference in the reflected spectrum.

I know now from one of (I think) Warren's notes that the webcam sensor is not capable to measure intensity's accurately. But I hope that by comparing value's I get a relative difference.

I use a matte black paper box and place a strong halogen light source parallel to the old videocassette style spectrometer inside. Both of them face a Matte black cardholder. This holds an A6 sized card. I start with a white colored card and place a smaller colored card near the first.

Instead of images I try to capture the combined values and compare the graphs to find estimate the difference with or without a different colored object in a near region.

My attempt and results

This variable/command will deliver the valuables for R, G, B and the medium or combined value. I'm looking for a way to get online the combined value. Also I have no idea how to get the wavelength value's of the x-axle.

Macro: setup: function() { // code to run on startup $W.mode = "average"
alert($W.full_data) }, draw: function() { // code to run every frame

} end macro

Questions and next steps

How do I get the combined values only? How do I get the average combined values over a small time period?

How do I get the corresponding wavelength values?

Why I'm interested


I'm not at all sure you can measure what you seem to be talking about, or at least not in the way you seem to be going about it. As far I know the effect of the perceived colour of an object being modified by surrounding colours in the visual field is a feature of the human visual system, including processing in the visual centres of the brain. It is a visual illusion.

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I read that. I tried anyway just to check if there was anything perhaps a small difference. And so far I noticed a completely different problem.

I was as it turns out not thinking this through. By placing a different colored in front of the card the spectrum changes but it's more like cutting the spectrum in halve.

Originally I wanted to see if I could find a match when different colored cards were measured under different kind of lightsource. But theorie already provided the answer for that. Which is the same as you just described. The color interpretation is based on brightness, hue and the color of the surrounding within the field of vision. I hoped to see the effect of the surrounding in the spectrum.

Originally, I had a serious sign in problem. I couldn't save the captures in the normal way and tried to collect data in a way that I could copy it into a spreadsheet.

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