Wright Field Scale Modelers. Color Mixing: Everything you thought you knew about color is wrong.

Transcription

1 Wright Field Scale Modelers Color Mixing: Everything you thought you knew about color is wrong.

2 Sources Written by a color scientist, Dr. Briggs. It is a bit technical. Principles of Color Technology, 3 rd ed, Roy S. Berns, John Wiley & Sons (2000) Handprint website by Bruce MacEvoy. Very comprehensive and at times extremely technical. MacEvoy is not a scientist, but much of his writing has been approved by Briggs. MacEvoy paints with watercolors, so some of his advice does not apply to us.

3 What is Color? Color is a sensation created in the mind in response to light. Color is not in the object, it is not in the light, it is only in our minds. Even though light does not have color, we often say green light because it is easier than saying light of a wavelength that triggers the sensation of green.

4 Spectrum Newton observed that a prism will refract sunlight into different wavelengths, which appear as different colors. (Rainbow)

5 Color Wheel If the spectrum is linear, how do we get a color circle?

6 Cone response

7 Opponent Model

8 Full circle

9 Reflectance Curve What object is this?

10 Metamerism

11 Factors that affect color appearance Change in illumination (daylight vs many types of indoor lighting) Change in environment (simultaneous contrast) Change of observer Change in media (photograph, printing, computer monitor) It is rare that a color reproduction actually matches an original object (Berns, p. 29)

12 Describing color Hue circular scale of colors, red, orange, yellow, etc Value lightness or darkness (aka tone) Chroma Color strength. Refers to the visual difference from a gray of the same value. Saturation is a similar, related concept.

13 Munsell Color Page

14 Hue Families Forget about primary and secondary colors for a moment. Those listed here are wrong.

15 What are the primary hues? Ask a traditional artist, they will tell you the 3 primaries are red, yellow, and blue. Ask someone who makes TVs and monitors, they will tell you red, green, and blue. Ask a printer, they will tell you cyan, magenta, and yellow. Ask a neuropsychologist, they will tell you red, green, blue, and yellow. In truth, there is no set of universal primary colors.

16 Misconceptions about color theory The follow statements are false All color is created by the mixture of three "primary" colors. You cannot mix a primary red, yellow or blue using any other colors. Fact: there is no set of three paint colors that can mix all other colors. Fact: there are many colors that are not mixable in paint. Fact: the ideal subtractive primaries are cyan, yellow, and magenta. Even though the RYB primaries are outdated, many artists still prefer them over the CMY primaries.

17 Temperature No one can agree on where the warm colors end and where the cool colors begin. In general, reds, yellows, oranges are considered warm. Green and Blue are considered cool.

18 Hue Bias Each hue family contains countless individual hues. A single hue leans to one side or another The following slides shows various shades of the basic hue families.

19 Yellows

20 Greens

21 Blues

22 Violets

23 Reds

24 Oranges

25 A true neutral gray has no hue at all. But hues with a very low chroma are still called gray. Usually the hue isn t specified, but a near gray is often referred to as warm or cool. Neutral Gray Reds Oranges Yellows Greens Blues Violets

26 Describe the hue

27 Describe the hue

28 Describe the hue

29 Describe the hue Be careful on this one. We have trouble distinguishing the hue when the chroma is low. The lower the chroma, the tougher it is to distinguish the hue.

30 If you are having trouble figuring out the hue of a certain color, you can use a computer or smartphone to help. Use the color picker tool to select a color in a photo, and turn the S(saturation) and V(value) all the way up. The new color will show you the hue. Original Color Hue

31 Value

32 Value For 2D artists, value is the most important of the 3 aspects of color

33 How to see a color s value The artist s squint Close your eyes halfway to ¾. This will blur the image and remove detail. It will also remove much of the hue information.

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38 Muted Dull Gray De-saturated Pale Neutral Muddy Bright Pure Clear

39 Putting it all together To mix colors, you must know Where you are Where you want to go The color wheel is Only a rough guide Neutral point

40 Color Space

41 Whichever wheel you pick, make sure it has Cyan and Magenta. Which color wheel is correct??

42 This is my favorite color wheel, by Bruce MacEvoy, available here Note this wheel lists artist watercolor paints, but it is still helpful.

43 Here, I have plotted two different colors on the color wheel.

44 In theory, when these two colors are mixed, the resulting color will fall along a line between the two colors. This is called a mixing path. The real world isn t so perfect.

45 In the real world, mixing paths rarely fall on a straight line. Here are some real world mixing paths mapped onto a color wheel. Note how on the top image, the mixing paths tend to curve inward. While the bottom image shows mixing paths that curve outward. The exact mixing paths are not predictable. That is the nature of paint and the imperfect nature of the color wheel. Images Dave Briggs,

46 I ve added a third color to the previous two. The mixing paths between all three colors form a triangle. Any color inside the triangle can be mixed with the three corner colors in some proportion. But remember, the mixing lines are rarely straight and the color wheel is not perfectly accurate.

47 Note that the farther apart two paints are, the duller their mixture will be. If you want to mix a bright color, you will need to mix two bright colors that are close together on the color wheel. Image by Bruce MacEvoy, d.html#step4

48 If the colors are far enough apart, the mixing path will go through the neutral point in the center. Such colors are called mixing complements. An example of such complements is Ultramarine Blue and Burnt Sienna. Note that mixing complements are pigment specific, not hue specific. Two paints of similar hues may have different mixing complements. Due to the inaccuracies of the color wheel, many mixing complements are directly across from each other on the wheel. See picture. Image by Bruce MacEvoy, Also note that some pigments, such as Viridian, have multiple mixing complements, while others have only one complementary pair or none at all.

49 Basic Mixing method The next series of slides is taken from the Handprint web site I suggest you read this page for a more thorough explanation.

50 Let s say we are starting with the following six colors (represented by circles): Hansa Yellow Cadmium Red Magenta Ultramarine Blue Phthalo Blue Phthalo Green From these, how would we go about mixing burnt sienna? (square)

51 First, we find a pair of paints that will give a mixing path through or close to our target color. None of the four possible mixing paths pass through the target. But four come somewhat close. This illustrates that many colors can be mixed more than one way.

52 Lets say the path we chose is Hansa yellow and Cadmium Red. But because our target does not fall exactly one the mixing path, we need to choose a third color to adjust the mixture. The three colors form a triangle that encloses the mixing paint. In this case, we could use Ultramarine Blue. See the handprint website for an explanation on how to estimate the proportions of the three paints om/hp/wcl/mix.html

53 How to match a color Learning to match a specific color is not hard, it can be learned in about an hour. Mark Carder describes the method using three traditional primary colors plus brown and white. Pyrole Rubine (crimson) Ultramarine blue (a violet-blue) Cadmium Yellow (orangish-yellow) Burnt Umber (brown) Titanium White You don t need to use these exact colors, get the closest you can of the bright colors. Use single pigment colors if available.

54 Summary of steps 1. Pick a paint that you have that is closest to the color you want to match. (In the video, Mark starts with a random color. This works as an exercise, but I don t recommend it for real life). 2. Match the value first. Adjust your paint to match the value of the target. Remember to use the artist s squint. To lighten the color, mix yellow or white or both. To darken the color, add blue or brown or both. If using acrylics, let the paint dry before you compare to your target. 3. Once the value matches the target, you can adjust the hue. Ask yourself one of the following questions. If you can t answer a question, move onto the next one. The order does not matter. Which color is more red? Which color is more orange? Which color is more yellow? Which color is more green? Which color is more blue? Which color is more purple/violet? 4. If the mixture needs more red, add red. If the mixture is too red, add the color opposite red on the color wheel (green). The complementary color will kill its opposite color.

55 Color matching, continued 5. After you adjust the hue in this manner, re-check the value and readjust if necessary. 6. Readjust hue and repeat until you get a match. In this video, Mark seems to combine hue and chroma into one step. But his method still works.

56 Hobby Paint vs Artists paint Hobby Paint Secret pigments Hodge-podge of pigments Formulated to be opaque Artist s paint Disclose pigments Many single pigment colors (such as the brightest colors. Tend to be transparent

57 Shading series As color moves from light into shadows, the saturation of the color remains constant. That is, the chroma changes at the same rate as the value. This assumes that the color of the object is constant and a single light source.

58 Once again, our computers can help us out here. Most graphics programs support HSV, HSB, HSL. Just change the value parameter (or brightness/lightness) and keep the H(hue) and S(saturation) the same.

59 Mixing Shadows How do we darken a color while keeping the saturation constant? Mixing just black will desaturate the color. Mixing a complementary color sometimes works, but only to a point. It will also desaturate the color. Options 1. Add a darker color of the same hue. 2. Add a darker color of an adjacent hue. 3. Add a similar color with a higher saturation, then darken with black or a complement. 4. Add black, then resaturate using bright colors (single pigment colors). Some shifting of hue in shadows is acceptable.

60 Paint Mixing Tips Both black and white paint have a tendency to shift the hue of mixtures toward blue. Thus, when mixing a gray from black and white, you get a bluish gray. If you want a neutral gray, add a bit of brown (such as burnt umber) to the mix. When you add black to yellow, you get green because of the blue-shift. (yellow and blue make green). You can compensate by adding a touch of red. Keep a record of mixtures you use on each model along with a sample of each mixture. I use an index card. Keep your mixtures to three colors or less (plus white). This makes it easier to remix the same color later. To reduce the chroma of a mixture, you can mix in a neutral gray of the same value. You can also use a complementary color, but only mix in small amounts. Mixing all your colors with a 3 primary palette is tedious. I don t recommend it for everyday use. Instead, I find a hobby paint that is as close as I can get to the desired color. Then I tweak the paint to achieve the desired color.

61 Some helpful websites The virtual Munsell color wheel--isn t exactly true to the Munsell system, but gets you in the ballpark. Enter a hex code and it will give you some technical information about the color and gives you matches to some brands of paints, including some hobby paints. Has information on many art and hobby colors. Gives hex codes for all colors (I don t know how accurate these are).

62 Android Apps Color Grab Real Color Mixer