Does anyone know how to measure the color of a Post-It note?

[Sherwood Botsford]

Put out a spectrum of post-it notes.

Using even illumination, preferably direct sunlight, take a picture with a digital camera.

Using the eyedropper tool in most photo editing apps, place it's cursor over each Post-it in turn. On most when you mouse over you will get an ordered triple (r,g,b) with the first number corresponding to red, the second green, and the third blue.

Consider however is 2,0,0 is 100% red. But it has only 1/50 of the red of 100,150,200 So you need to compare the amount of red to the total luminance. This is usually calculated = 0.299 R + 0.587 G + 0.114 B as your eye is most sensitive to green and least to blue, so it takes a lot of extra blue to appear brighter.

 

[sophiecentaur]

Consider however is 2,0,0 is 100% red

I have to ask "Which Red?" Will it be the same red that there lab down the road is using?

 

[lekh2003]

You would be looking for a spectrometer. Such at this:
http://ikancorp.com/productdetail.php?id=1975&model=mk350d

This is not something that your high school is likely to have.
But the right technical college may be willing to demo one for you.
Some State labs might have one - and they are often open to demo their equipment to high schoolers.

Some private schools have them, surprisingly. I attended a private school for a few years and they had one. We even found electron guns in dusty cardboard boxes and other unused university-level equipment.

As for this crisis, I really don't think you can quantify color, especially in an art class. It's all open to interpretation. There is no universal standard for what is the reddest color, at least if it concerns artists. Wavelengths won't be able to satisfy any art student.

 

[sophiecentaur]

It's all open to interpretation.

Of course it is. But it is still possible to 'measure' two sources of light (light sources or illuminated objects) and to predict whether or not most people will say that they match. So a quantitative approach to this subject is very much worth while and allows colour TV and printing to work very well.
It is not necessary for a computer to say to itself " ah yes, that is pale pink" for it to select a set of pigments to mix you up a pot of (matching) pale pink paint.

 

[Gapster]

Hi all! I initially came here to peruse the threads about Vacuums but stumbled across this topic. Having worked in the print and reprographic industry ( specifically colour correction from computer to paper) I can offer my twopenceworth.

Taking the initial OP on a lighter note (scuse the pun)...

If it is simply a question of personal colour bias then you would both have to agree on a method of determining the colour measurement of the particular post-it that has fuelled the debate. Given that the paper colour is likely to be generated withing the print and paper industry I would suggest going to a local offset printing company and asking them if they have a colour densitometer as a benchmark (and simple) way of determining colour separation/qualities.