(word processor parameters LM=8, RM=75, TM=2, BM=2) Taken from KeelyNet BBS (214) 324-3501 Sponsored by Vangard Sciences PO BOX 1031 Mesquite, TX 75150 There are ABSOLUTELY NO RESTRICTIONS on duplicating, publishing or distributing the files on KeelyNet! January 14, 1991 COLOR1.ASC -------------------------------------------------------------------- Color Theory Basics Color theory explains what color is, how the human eye sees color and the methods used to create all the colors in the color spectrum. To begin learning about color, we must start with light. We must have light to see things. Light shines on an object and is reflected back to our eyes, allowing us to see the objects as they are. Objects ONLY REFLECT THE COLORS THEY ARE MADE UP OF, and it is these colors that are received by the eye. When we refer to light, we mean white light. White light is made up of EQUAL AMOUNTS of RED, GREEN and BLUE light. If we were to shine three PURE beams of red, green and blue light together and slightly overlap them, we can see that where the three overlap, the color is white. -------------------------------------------------------------------- PRIMARY COLORS RED, GREEN and BLUE are referred to as the PRIMARY COLORS of light. Because we ADD them together to create color, we call them ADDITIVE COLORS. Where two of the beams overlap, we actually create a third different color. Where we overlap the BLUE and GREEN, we create a new color known as CYAN. CYAN is a combination of blue light and green light. Where BLUE and RED overlap, we get a color called MAGENTA. MAGENTA is a combination of blue and red light. Where the RED and GREEN beams overlap, we create YELLOW! Remember, these are pure beams of colored light. YELLOW is created by combining equal amounts of red and green light. CYAN, MAGENTA and YELLOW are called the SUBTRACTIVE COLORS, because we create color by using them to SUBTRACT COLOR from WHITE LIGHT. To help us keep these colors in proper perspective with each other, we shall refer to the color triangle below. The colors at the Page 1 POINTS of the triangle are the three additive colors, RED, GREEN and BLUE. The three colors along along the SIDE of the triangle are the SUBTRACTIVE COLORS, MAGENTA, YELLOW, and CYAN. The subtractive colors are placed between the two additives that they are made up of. For example, the magenta is between the red and blue because red and blue make magenta. RED @ * * (R + B = M) MAGENTA<<<<@ @>>>>YELLOW (R + G = Y) * * * * BLUE<<<<@ * * * * @ * * * * @>>>>GREEN CYAN (B + G = C) -------------------------------------------------------------------- Up until now, we have been combining two primary colors at a time. What would happen if we add together one SUBTRACTIVE color and one ADDITIVE color of light? Red + Cyan = White Light (green + blue) Blue + Yellow = White Light (red + green) Green + Magenta = White Light (red + blue) -------------------------------------------------------------------- COMPLIMENTARY PAIRS Complimentary pairs are the combination of one additive and one subtractive color together to recreate white light. If you keep in mind that the subtractive colors are made up of two additive colors, by adding the remaining additive color we get white light again. Blue is complementary to Yellow Green is complementary to Magenta Red is complementary to Cyan In most of the situations where we find color, it has been derived through the subtractive process. Paintings, photographic prints and color negative film all rely on the SUBTRACTIVE colors to create color. The most common application of the additive colors is television. It uses a combination of red, green and blue dots to create a color picture on the screen. -------------------------------------------------------------------- Page 2 FILTERS A filter is a device that will block out certain amounts or kinds of light. A NEUTRAL FILTER ABSORBS EQUAL AMOUNTS of the red, green and blue that make up the white light. The transmitted colors, or those allowed to pass, are the same as the original colors, just not as intense. NEUTRAL FILTER WHITE RED>>>>>>>>>>>>>NNN>>>>>>>>>>RED all LIGHT RAYS GREEN>>>>>>>>>>>NNN>>>>>>>>>>GREEN colors BLUE>>>>>>>>>>>>NNN>>>>>>>>>>BLUE pass Neutral shades of sunglasses produce this effect of reducing the intensity of the colors without changing the colors themselves. -------------------------------------------------------------------- In the photographic process, subtractive colors are used to create color. Color filters are used to SELECTIVELY choose what color we want to see while eliminating other unwanted colors from light. The use of filters is basic to the understanding of how photographic film and paper are designed to reproduced the colors of the subject. -------------------------------------------------------------------- If a RED filter is placed in front of a beam of white light, you will see the color RED. Red light is allowed to pass or be transmitted through while the green and blue light are blocked or absorbed. RED FILTER WHITE RED>>>>>>>>>>>>>RRR>>>>>>>>>>RED only RED LIGHT RAYS GREEN>>>>>>>>>>>RRR passes through BLUE>>>>>>>>>>>>RRR -------------------------------------------------------------------- If a GREEN filter is placed in front of a beam of white light, you will see the color GREEN. Green light is transmitted through while the red and blue light is absorbed. GREEN FILTER WHITE RED>>>>>>>>>>>>>GGG only GREEN LIGHT RAYS GREEN>>>>>>>>>>>GGG>>>>>>>>>>GREEN passes through BLUE>>>>>>>>>>>>GGG -------------------------------------------------------------------- If a BLUE filter is placed in front of a beam of white light, you will see the color BLUE. Blue light is transmitted through while the red and green light are absorbed. Page 3 BLUE FILTER WHITE RED>>>>>>>>>>>>>BBB only BLUE LIGHT RAYS GREEN>>>>>>>>>>>BBB passes through BLUE>>>>>>>>>>>>BBB>>>>>>>>>>BLUE Remember that ANY filter TRANSMITS ITS OWN COLOR. -------------------------------------------------------------------- If you place a CYAN filter in front of a beam of white light, you will find the RED light is ABSORBED while the BLUE and GREEN light are TRANSMITTED. This is because CYAN is MADE UP of BLUE and GREEN and a CYAN filter TRANSMITS its own color. CYAN FILTER (full strength) WHITE RED>>>>>>>>>>>>>CCC only GREEN & BLUE LIGHT RAYS GREEN>>>>>>>>>>>CCC>>>>>>>>>>GREEN passes through BLUE>>>>>>>>>>>>CCC>>>>>>>>>>BLUE (absorbs RED) -------------------------------------------------------------------- If you place a MAGENTA filter in front of a beam of white light, you will find the GREEN light is ABSORBED while the RED and BLUE light are TRANSMITTED. This is because MAGENTA is a combination of RED and BLUE. MAGENTA FILTER (full strength) WHITE RED>>>>>>>>>>>>>MMM>>>>>>>>>>RED only RED & BLUE LIGHT RAYS GREEN>>>>>>>>>>>MMM passes through BLUE>>>>>>>>>>>>MMM>>>>>>>>>>BLUE (absorbs GREEN) -------------------------------------------------------------------- If you place a YELLOW filter in front of a beam of white light, you will find the BLUE light is ABSORBED while the RED and GREEN light are TRANSMITTED. This is because YELLOW is a combination of RED and GREEN. YELLOW FILTER (full strength) WHITE RED>>>>>>>>>>>>>YYY>>>>>>>>>>RED only RED & GREEN LIGHT RAYS GREEN>>>>>>>>>>>YYY>>>>>>>>>>GREEN passes through BLUE>>>>>>>>>>>>YYY (absorbs BLUE) Each subtractive filter ABSORBS ONE COLOR of light while TRANSMITTING the other TWO COLORS. -------------------------------------------------------------------- Often, it is necessary to use more than one filter at a time to obtain the desired results of blocking out ALL BUT ONE COLOR. The following diagrams illustrate how a set of two SUBTRACTIVE filters work together to filter out ALL BUT ONE COLOR from a beam of white light. Page 4 MAGENTA CYAN FILTER FILTER WHITE RED>>>>>>>MMM>>>>>>>>>CCC only BLUE LIGHT RAYS GREEN>>>>>MMM CCC passes through BLUE>>>>>>MMM>>>>>>>>>CCC>>>>>BLUE If a MAGENTA and CYAN filter are used together, you can see the MAGENTA filter ABSORBS the GREEN and TRANSMITS the RED and BLUE. Then the CYAN filter ABSORBS the RED and allows the BLUE to be TRANSMITTED. We know from our triangle that CYAN is made from GREEN and BLUE, but since the GREEN was ABSORBED earlier by the MAGENTA filter, there is NO GREEN for the CYAN filter to be TRANSMITTED, resulting in only the remaining BLUE color. -------------------------------------------------------------------- If CYAN and YELLOW are used together, you can see the CYAN filter ABSORBS the RED and allows the BLUE and GREEN to be TRANSMITTED. Then the YELLOW filter absorbs the BLUE and allows the GREEN to be TRANSMITTED. From our triangle we see YELLOW is made from RED and GREEN, but since the RED was ABSORBED earlier by the CYAN filter, there is no RED for the YELLOW filter to TRANSMIT, resulting in only the remaining GREEN color. CYAN YELLOW FILTER FILTER WHITE RED>>>>>>>CCC YYY only GREEN LIGHT RAYS GREEN>>>>>CCC>>>>>>>>>YYY>>>>>GREEN passes through BLUE>>>>>>CCC>>>>>>>>>YYY -------------------------------------------------------------------- If you use the MAGENTA and YELLOW filters together, you see the MAGENTA filter ABSORBS the GREEN and allows the RED and BLUE to be TRANSMITTED. The YELLOW filter then ABSORBS the BLUE and TRANSMITS the RED. From the triangle, we can see that YELLOW is made from RED and GREEN, but since the MAGENTA filter ABSORBED the GREEN earlier, there is no GREEN, leaving only the remaining RED color. MAGENTA YELLOW FILTER FILTER WHITE RED>>>>>>>MMM>>>>>>>>>YYY>>>>>RED only RED LIGHT RAYS GREEN>>>>>MMM YYY passes through BLUE>>>>>>MMM>>>>>>>>>YYY -------------------------------------------------------------------- With the YELLOW filter first, we see the BLUE is ABSORBED and TRANSMITS the RED and GREEN. When the RED and GREEN reach the MAGENTA filter, the GREEN is ABSORBED and the RED light is transmitted. Page 5 From the triangle, we know MAGENTA is made from RED and BLUE, but since the YELLOW filter ABSORBED the BLUE earlier, only the RED component remained to be transmitted. YELLOW MAGENTA FILTER FILTER WHITE RED>>>>>>>YYY>>>>>>>>>MMM>>>>>RED only RED LIGHT RAYS GREEN>>>>>YYY>>>>>>>>>MMM passes through BLUE>>>>>>YYY MMM As this comparison showed, it really isn't important in which order the two filters are used, the single color that remains is ALWAYS the same. Referring to the color triangle will help keep the color relationships straight for you. -------------------------------------------------------------------- Now, what would happen if you put ALL THREE SUBTRACTIVE filters in front of a light beam? As you can see, the combination of all THREE FILTERS TOTALLY ABSORBS ALL of the light and NO COLORS are allowed to pass through. Equal intensity filters of CYAN, MAGENTA and YELLOW make up what is called a NEUTRAL FILTER. This means that the color of light seen will be NEUTRAL or HAVE NO COLOR. MAGENTA CYAN YELLOW FILTER FILTER FILTER WHITE RED>>>>>MMM>>>>>>>CCC YYY NO LIGHT LIGHT RAYS GREEN>>>MMM CCC YYY passes through BLUE>>>>MMM>>>>>>>CCC>>>>>YYY Up to this point, we have been talking about FULL STRENGTH filters. In other words, a full strength CYAN filter would ABSORB all RED light and TRANSMIT GREEN and BLUE light. It is possible to VARY THE INTENSITY of the filter so that SOME amount of colored light will be ABSORBED. This means that a LOWER INTENSITY CYAN filter would ABSORB some RED and TRANSMIT some RED light alown WITH the GREEN and BLUE light. CYAN FILTER WHITE RED>>>>>>>>>>>>>CCC> > > > > RED only some RED LIGHT RAYS GREEN>>>>>>>>>>>CCC>>>>>>>>>>GREEN FULL GREEN BLUE>>>>>>>>>>>>CCC>>>>>>>>>>BLUE FULL BLUE If we CHANGE THE INTENSITY OF A NEUTRAL FILTER, we will vary the intensity of RED, GREEN, and BLUE light TRANSMITTED. Since the filter is NEUTRAL, the RED, GREEN, and BLUE light will be in EQUAL AMOUNTS causing the light to APPEAR NEUTRAL in color. The table below will serve as a reference to the three SUBTRACTIVE colors that are most commonly used as filters in color film and paper construction. Always keep in mind the COMPLEMENTARY PAIRS. Page 6 Filter Color Light Transmitted Light Absorbed CYAN GREEN & BLUE RED (CYAN) MAGENTA RED & BLUE GREEN (MAGENTA) YELLOW RED & GREEN BLUE (YELLOW) It is important to mention here that so far we have been discussing filters that are ideal, or perfect, meaning they absorbe the complimentary color completely. In reality, this is not so. The filters are NOT PERFECT, so a small amount of the complimentary color does get transmitted, and a small amount of the other two colors are absorbed. However, it should be noted that the change in intensity will not create a problem. One must remember that we are dealing with PURE colors. Shades of pure and complimentary colors arise from the action of imperfect filtering. Therefore, color correction/compensation must ultimately be decided by the viewer. -------------------------------------------------------------------- A REVIEW WHITE LIGHT is comprised of EQUAL AMOUNTS OF RED, GREEN and BLUE light added together. Thus, red, green and blue are called the PRIMARY COLORS of light. We can also create color by ABSORBING RED, GREEN or BLUE from white light using SUBTRACTIVE COLOR filters, CYAN, MAGENTA, and YELLOW. ANY FILTER TRANSMITS ITS OWN COLOR AND ABSORBS ITS COMPLIMENTARY COLOR. CYAN absorbs RED light and allows BLUE and GREEN light to pass. MAGENTA absorbs GREEN light and allows BLUE and RED light to pass. YELLOW absorbs BLUE light and allows RED and GREEN to pass. When two or more filters are used together, it doesn't matter in which order they are placed, the result will be the same. When all three subtractive filters of equal intensity are combined, the result is a NEUTRAL FILTER. When placed in front of a beam of white light, the light transmitted will be NEUTRAL in color and its BRILLIANCE depends on the intensity of the filter. Filters are not perfect in design, so a very small amount of the color of light that should be absorbed actually does pass through the filter. -------------------------------------------------------------------- Page 7 If you have comments or other information relating to such topics as this paper covers, please upload to KeelyNet or send to the Vangard Sciences address as listed on the first page. Thank you for your consideration, interest and support. Jerry W. Decker.........Ron Barker...........Chuck Henderson Vangard Sciences/KeelyNet -------------------------------------------------------------------- If we can be of service, you may contact Jerry at (214) 324-8741 or Ron at (214) 242-9346 -------------------------------------------------------------------- Page 8