Essay on Chapter 11

Essay on Chapter 11 Essay on Chapter 11 Chapter 11 Preparing a Document for Prepress and Printing Objectives Explore color theory and resolution issues Work in CMYK mode Specify spot colors Create crop marks Create bleeds Save file as a PDF Explore Color Theory and Resolution Issues Energy from the sun hits the earth in waves: X-rays Gamma rays Ultraviolet rays Visual light rays (white light) Explore Color Theory and Resolution Issues White light broken down into seven distinct colors (as seen in a rainbow) Red Orange Yellow Green Blue Indigo Violet Explore Color Theory and Resolution Issues Colors in visible spectrum can be broken into red, green, and blue (primary colors). – Primary colors cannot be reduced – Additive refers to the fact that the primary colors combine to produce other colors – Red, green, and blue, when combined equally, produce white light – True black is the absence of all light Explore Color Theory and Resolution Issues White light Explore Color Theory and Resolution Issues Subtractive primary colors Three things can happen when light strikes an object: – Reflection – when light ‘bounces’ off the object – Absorption – when light is not reflected – Transmission – when light passes through an object Explore Color Theory and Resolution Issues Depending on physical properties of object, varying amounts of light are reflected, absorbed, and transmitted. Red, green, and blue light not reflected in equal amounts. Color is based on percentages of red, green, and blue reflected, and the color that combination of light produces. Explore Color Theory and Resolution Issues Explore Color Theory and Resolution Issues Cyan, magenta, and yellow are called subtractive primary colors. Each is produced by removing or subtracting one of the primary colors completely. Overlapping all three pigments would absorb all colors. Explore Color Theory and Resolution Issues Cyan is â€Å"minus red† Magenta is â€Å"minus green† Yellow is â€Å"minus blue† Explore Color Theory and Resolution Issues Color printing uses the three subtractive primary colors plus black to produce a color image or tint. The standard color for paper is white. Cyan, magenta, and yellow are manufactured to be transparent. The color you see on a printed page is light reflected off the page. Explore Color Theory and Resolution Issues The color of the printed image is reflected off the paper, not the inks Explore Color Theory and Resolution Issues CMYK inks (process inks) are not perfect. Ability to transmit light not perfect. In theory, overlapping all three inks should produce black because no light would be reflected. Explore Color Theory and Resolution Issues The image on the left was printed with only CMY inks Black inks add contrast and depth to image on the image on the right Explore Color Theory and Resolution Issues Illustrator is a vector-based drawing program. Graphics you create are called vector graphics. Vector graphics are resolution independent because they are not comprised of pixels. You can resize vector graphics without any concern for quality. Explore Color Theory and Resolution Issues You can convert vector graphics to bitmap graphics by a process called rasterization. Bitmaps are comprised of a rectangular grid of colored squares called pixels. Pixels is short for picture elements. Explore Color Theory and Resolution Issues Images composed of pixels include: Scanned images Digital images Rasterized Illustrator graphics Explore Color Theory and Resolution Issues The number of pixels in a given inch is referred to as the image’s resolution. To be effective they must create the illusion of continuous tone. Explore Color Theory and Resolution Issues Effective resolution refers to the resolution of a placed image based on its size in the layout. Relevant only to bitmap graphics because vector graphics do not have pixels. Explore Color Theory and Resolution