PP and numbers

[rickp1]

Hey guys and gals,
I;ve seen a couple of references to PP and along with that some numerical values.

Can someone explain that to me?
Are there a set of numbers for exposure, color, contrast etc....

Thanks
R.

[i speak in math]

In photoshop, the sliders for contrast, saturation, etc... have numerical values. For instance, the contrast slider starts at 0 and you can add or remove contrast by consecutive integers from there. So, +1, +2 or -1, -2 or you can slide it all the way up to +100 if you want.

[rickp1]

I speak in math,
I'm familiar with the sliders and the corresponding numbers, but the numbers I'm talking about are different.
I watched a tutorial where a guy used some numbers to get the tone in a picture right. He also mentioned a formula for figuring out the correct numbers too. He didn't use the formula just mentioned it. The numbers he was adjusting were in the 200's and 300's, and again if I remember right he was adjusting tone or contrast.

I know this is VERY vague, but I'm hoping it's enough that someone will know what I'm referring to and can explain it better and more clearly.


Thanks
R.

[i speak in math]

do you have a link to said tutorial or know where you saw it?

[rickp1]

I did a search in youtube and saw it there. I just looked in my history but no luck. At the time I pretty much just dismissed the the whole thing and kept looking for what I was looking for.

R.

[Sterling]

RGB numbers (0-255)?

[LeeR]

He was most likely refering to RGB numbers (Red, Blue, Green). They run from 0 to 255 and the values are critical for getting for skin tones right.

[teaking]

Because you mention tone correction I would take a guess the numbers he is referring to are colour values either RGB (red green and blue) or CMYK (cyan magenta yellow and key) for exambple R128 G128 B128 is gray.

By the way a great tip I read for advanced skin tone colour correction once you have corrected your white point, the formula: R(ed) is greater G(reen) and G is greater than B(lue) and the difference between R and G is greater than or double the difference of G and B.

Sounds complicate but works pretty good there no set numbers as they are different in each photo its more to do with the ratios.

[rickp1]

Hey guys,
That sounds about right.
So how do these numbers work to get the right colors right?

[OsmosisStudios]

If youre talking about RGB colours, then its easy.

Pixels are made up of 3 dots: A red, a Green, a Blue.

What youre seeing in these numbers is the value given to each dot. So if you have a pixel that is (255,255,255), it means that each dot is at maximum. If the pixel is (0,0,0) then each dot is at its minimum. In these cases you have white and black respectively.

If you have (255,0,0) then the red is at maximum, but blue and green are at their minimum: this gives you pure red. Pure green is (0,255,0) and Pure blue is (0,0,255).

Different colours are obtained through altering these numbers. For instance, (200,25,150) is a purple colour.