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Lecture Comments (2)

1 answer

Last reply by: Professor Brown
Mon Jun 10, 2013 5:18 AM

Post by tori choi on June 9, 2013

i thought the higher temp. the reddish and the cooler the blueish.. ???

Light & Color

  • "Light is Everything". Without good lighting, photographs have no soul. Good composition with bad lighting = poor photo.
  • There are basically two types of light: Transmitted (monitors) and Reflected (Print - ink and paper)
  • Transmitted light is made up of Red, Green, and Blue.
  • Reflected light is Cyan, Magenta, Yellow and Black.
  • A Color Space is a range of color called a Gamut
  • The three primary gamuts are Adobe RGB, sRGB, and CMYK.
  • Use Adobe RGB because it covers both sRGB and CMYK, and has a little bit of extra color in its range.
  • Set your camera and Photoshop to default at Adobe RGB.

Light & Color

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Lesson Overview 0:06
  • A Simple Lesson in Light & Color 1:07
    • What is Light?
    • Brightness
    • Color
    • Transmitted Light vs. Reflected Light
    • Transmitted Light is Additive
    • Reflected Light is Subtractive
    • Why Is This Important In Photoshop?
  • Color Spaces 7:48
    • Visible Spectrum of Color
    • ProPhoto RGB
    • Adobe RGB
    • sRGB
    • CMYK
    • Set Camera to Adobe RGB and Photoshop Default to Adobe RGB
    • RGB vs. CMYK

Transcription: Light & Color

Hi everyone, Mike Brown here again, welcome back to educator.com's Adobe Photoshop CS6 course.0000

In this lesson, we're going to talk about light and color spaces, and what's the value of light.0006

We were talking in the last lesson of quality, starting with the settings in your camera, and then the picture comes out and how we work it and make it correct and improve it in Photoshop, but what did you take a picture of?0014

You took a picture of a scene or a person or something that is all light, and in photography, light is everything--the quality level, the intensity level, the color of the light, the way light works on a subject is of vital importance, and especially with Photoshop we want to get the correct light, so it's valuable to understand what light is.0028

Color spaces are ranges of color, and there are different color spaces in Photoshop, that we can (and our camera for that matter) that we can work in so it's valuable for me to explain what those are.0050

Once you understand these, it will help you as we move into Photoshop, so let's go to it!0063

A simple lesson in light and color, what is light?0069

Technically, it's electromagnetic radiation that our eyes can interpret, and that's called vision.0072

We perceive light as a range of brightness and color, brightness being the intensity of the light, and let me give you an example of how that works...0079

Bright sunny day, noon, stop sign, very brilliant red, clouds move in, it's still red but it's a different shade of red--it's a little darker and a different shade of red--it's still that same red, it's just got darker because the intensity level of the light went down when the clouds covered the sun.0090

Same thing as the sun goes down in the afternoon, as it begins to angle through the atmosphere, it gets a little darker, the color of the light (which is what we're going to talk about in a moment) changes because now the light goes through a lot more of the atmosphere and the particles inside the atmosphere bounce around the rays of light and change the wavelengths.0111

So brightness...exposure by the way, in the world of Photoshop, exposure affects color, color does not affect exposure.0135

Color is the temperature of the light--the actual color temperature of the photons, that's what creates the entire spectrum of color.0147

An example of this, is when you look up at night, at a clear night, and you see stars--you see white, blue, yellow, red stars, what you're seeing is higher temperatures or lower temperatures of light.0155

The higher temperature stars are more bluish, the lower temperature stars are more reddish and everything in between creates the spectrum, so the two features of light are brightness and color.0169

Now we also see light in our world two different ways; there's transmitted light and reflected light.0181

Transmitted light is our monitor or TV set or your smartphone, for example, the screens are actually projecting the light directly into your eye--that's where beams of light are broadcast directly to your eyes, that's transmitted light.0190

Reflected light is...everything you see by the way, even in the daytime, you're walking on the street and you're looking at that Stop sign, that's reflected light--the light source was the sun, and it hit the Stop sign and reflected into your eye.0210

In our case, the two things that we work with in Photoshop are either preparing things for the internet or to be seen on a computer or smartphone, something that's a transmitted light, or we go out to print, where the light is reflected and the difference is they're two different types of light.0224

Reflected light, transmitted light--where light is absorbed by the ink and paper, and the color that you see is the remaining reflected wavelengths.0244

When you see the Stop sign for real, you're seeing reflected light--that Stop sign absorbed every wavelength of light except the red and it bounced at you, whereas when you look at red here on a monitor that's being transmitted directly to you and that's a combination of colors and we'll go on and talk about that right now.0252

Transmitted light--it's what's called additive light; red, green and blue combine to make the entire spectrum.0276

Here in a monitor or the iPhones or your television screen, it actually has red, green and blue, if you could blow up these little pixels in here there are red, green and blue pixels, and they light up and combine to make the entire range of color.0288

Pure red, pure green and pure blue is white...nothing is black--let me actually give you an example of that very simply--right here we have white, red and black.0306

I'm going to pull up the Info panel, here you can see that in the corner, and I'm going to take my color picker, and as I move it around, look--I'm moving in white, look at the R, G and B values.0319

Zero is nothing, 255 is pure, so you notice when it moves on the white, that it's 255, 255, 255.0332

If I go over the black letters, notice over there?0342

It's changed to zero, zero and zero, so you're not seeing anything being transmitted at all, here, pure red, pure green and pure blue.0346

Now here I have pure red on the type--watch this--take a look at the RGB, what do you think's going to happen?0355

If it's pure red, it should be 255, zero, zero, watch...there you go, pure red, 255, zero, zero.0361

That's how transmitted light works...additive and subtractive, that's the additive light of our monitor, reflective light is subtractive, and it's made up of cyan, magenta, yellow and black so you can see already that it's a little difficult for reflected prints to create pure red--there is no red, it has to be a combination of cyan, magenta, yellow and black.0372

Same with green, where's the green in here?0402

Blue is not too bad, cyan and a little bit of black can make the blues change--it's not too bad but it has a problem too, you have different colors creating what we see.0405

Additive, and the difference here, white is everything, in subtractive or print world, white is just nothing, all the wavelengths are being absorbed by a piece of white paper, you see no reflection whatsoever, a black piece of paper, everything is coming back at you and combining, and why is this important in Photoshop?0416

Your photographs or graphic art will be output either for the web or other places which are all perceived either on a computer monitor, a television screen or a smartphone which are transmitted light, and the other way is it's going out to print, which works with CMYK, and it's reflected color, two different worlds.0438

Alright, so that explains a little about light and color, and let's go a little bit deeper and talk about color spaces.0463

Now, I have a turn off layer, a color space is a range of color.0473

It's called a gamut, you will see that word appear in a lot of places--now you know gamut is simply a range of color, and there are different gamuts that we are dealing with in the world of Photoshop.0480

First of all, if you look at this graph over here (let me pop it up one more for you) what you're seeing are one, two, three, four, five color spaces.0493

The one that's underneath that has this curve around the side, flat edge and flat up here, is the visible spectrum of color, and what that is, this is the range of color that our human eyes can perceive.0505

You notice it's fairly large.0519

Pro photo color space, pro color RGB is the big triangle, and you'll notice interestingly enough, that in pro photo RGB, it has more blue than the actual eye can see, also green, so there are actually colors in the pro photo's color space that you can't see and can't reproduce at all.0522

Now, if this is the largest working color space, and it's used primarily for very high end professional work, most of the time the images are worked in what's called a 16 bit color mode which has gazillions of colors as you can see by the color space.0546

We work mostly in Photoshop and with our imaging and graphics in 8 bit color, which has 16.7 million colors, and I'll show you the difference in just a moment.0565

Pro photo, we're not going to use it, it takes up a lot more space, the files are huge, if your computer doesn't have enough RAM and memory, it's going to work a lot slower.0577

We work in other color spaces--I just wanted to identify that for you.0588

The other three are what we're going to be dealing with; Adobe RGB, SRGB and CMYK.0593

Adobe RGB is a color space that is, in this case, the bold triangle, and you notice that this corner of the triangle is right on the edge of visible color, on the blue spectrum over here, it loses just a little bit in the reds and purples, up a little bit, a little bit of yellow, and a significant amount of green over either the visible spectrum or the pro photo RGB.0599

But, this color space is a larger color space than either of the other two that we're involved with--let me explain further, so there's your Adobe RGB color space.0627

The fourth one is SRGB, this is the default color space for your cameras, and for Photoshop.0640

It's also the default color space that a jpeg is automatically going to shoot if you shoot it in your camera, and that's the smaller triangle--let me zoom that up a little bit so you can see it better.0650

Here's Adobe RGB...the bold triangle, SRGB is this smaller triangle and you notice a lot less green, pretty much the same in the blues but shades of blues are dropped as well, purples are dropped, not too much--purples are fine, reds dropped just a little bit, as you come up mostly in the yellows, greens, and down a little bit in the blue shades.0664

It's a little bit smaller but it's not horrendously small.0690

Now...the other color space, the last one, is the color space for printing ink on paper, and this color space is the kind of curved triangle if you will right here, and if you'll notice that I identified that as CMYK.0694

Notice our SRGB color space, there are more colors up in the green and light blues available than SRGB, also the colors fall on the reds compared to either Adobe or SRGB, and there's significant fall off in the blues compared to either SRGB or Adobe RGB and why is this all important?0713

Since Adobe RGB is an available color space for every camera and in Photoshop, it's the best color space for you to shoot in, because SRGB is the color space that's our monitor color space, CMYK is printing color space and if you look at the Adobe RGB broad triangle, except for a little in the yellows with the CMYK, it has more color than either of the other two.0738

So if we work in Adobe RGB and output either to a monitor with SRGB, or to CMYK, we are ensured that...every color that's available in those two color spaces, we can fit it in there, that's the reason we want to use it.0771

So, to make this simple, for consistency and to give yourself plenty of color range, set your cameras to shoot Adobe RGB--go into your menu, find the color spaces and change it from SRGB to Adobe RGB, and life will be just fine.0790

Set your Photoshop default to Adobe RGB under the color settings, and that's under your Edit menu, right down here at color settings, and here's the box, and under the working spaces at RGB, you will see by default it will say SRGB, click the button, run it up, and use...0809

You could do pro photo, but it's going to take a lot of space, go ahead and set it at Adobe RGB--that way your camera matches Photoshop, and you're ready to rock and roll.0830

OK, always use Adobe RGB even for printing unless a client or a printer requests a CMYK file, and a final thought, I want to show you the difference between the RGB color space, either one of them, and CMYK in printing to show you how different it is and you have to be thinking about this when you're working.0842

This is RGB, Adobe RGB, we're looking in the bold triangle color.0866

Under the View menu, I can view what it will look like when it's printed in CMYK.0872

I'm going to move this over so you can see this happen, View, Proof Colors--watch the greens and blues, and look what happened--they got very, very dull, not so much in the reds but very, very dull.0879

Come back, there's RGB, and there is CMYK--the difference between transmitted light and reflected light shows you right there.0892

So there you have a lesson in light and color spaces, and like I said, the big thing to get out of this lesson is set your camera and Photoshop to default at Adobe RGB color space.0905

I'll see you in the next lesson.0925