IT154 Midterm Study Guide

Transcription

1 IT154 Midterm Study Guide These are facts about the Adobe Photoshop CS4 application. If you know these facts, you should be able to do well on your midterm. Photoshop CS4 is part of the Adobe Creative Suite 4. As shown in the accompanying figure, the gray work area and the panels are referred to collectively as the workspace. When you point to many objects in the Photoshop window shown in the accompanying figure, such as a tool or button, Photoshop displays a tool tip. A shortcut menu sometimes is known as a context menu. To open a photo, you bring a copy of the file from the storage location to the screen where you can make changes to the photo. When you have a print copy of a picture that you wish to use in Photoshop, rather than a digital file stored on your computer, it sometimes is necessary to digitize the picture using a scanner. Each menu contains a list of commands you can use to perform tasks such as opening, saving, printing, and editing photos.

2 As shown in the figure above, the Photoshop workspace consists of a variety of components to make your work more efficient and to make your photo documents look more professional. A check mark in a Photoshop menu like the one in the accompanying figure means the setting is currently used or displayed. When an ellipsis follows a menu command like those shown in the figure above, clicking that command will display a dialog box. As shown in the previous figure, if you point to a command on a menu that has an arrow to its right edge, a submenu displays another list of commands.

3 If a command does not immediately appear on a menu like the one in the accompanying figure, it is referred to as a hidden command. If you press and hold the CTRL key when you click the menu name like those shown in the accompanying figure, all menu commands including hidden ones will display. The options bar shown in the accompanying figure displays below the menu bar, and contains buttons and boxes that allow you to perform tasks more quickly than using the menu bar and related menus. The item shown in the accompanying figure is sometimes called the Control panel. You can dock the item in the accompanying figure at the top or bottom of the screen, or float it in any other location in the workspace. You can move the item in the accompanying figure by using the gray gripper bar located on the left of the options bar. The item in the accompanying figure changes to reflect the tool currently selected on the Tools panel. The Tools panel is a group of buttons, similar in general purpose, organized into a movable toolbar. The document window is the light gray area within the workspace that displays the active file or image. The light gray title bar at the top of the document window displays the name of the file, the magnification, and the color mode. The display area is the portion of the document window that show the photo or image. Pressing the TAB key toggles the display of panels on and off. A period separates a file name and its extension. EPS files can contain both bitmap and vector graphics. The default setting for file extensions in Photoshop is to use a three -letter extension. PDF (Portable Document Format) is a flexible file format based on the PostScript imaging model that is cross-platform and cross-application. JPG is a standard format used by photo hardware devices that supports many different color modes, and one that can be used on the Web. Zooming allows you to focus on certain parts of a photo. The rectangle with the red border in the Navigator panel is called the proxy view area. If you make a mistake while dragging the cropping area and want to start over, you can press the ESC key, which cancels the selection. Photoshop keeps track of all your edits in the History panel. A border is a decorative edge on a photo or a portion of a photo. A pixel is an individual dot of light that is the basic unit used to create digital images.

4 Blending modes are the ways in which pixels in an image are affected by a color. Photoshop uses a mathematical process called interpolation when it changes the number of pixels. The resampling process adds new pixels to a photo to match those already there. The GIF format is a compressed graphic format designed to minimize file size and electronic transfer time. Metadata is divided into several categories: file information, creation data, image usage being among them. Adobe Bridge is like a database for all your photos. As shown in the accompanying figure, perspective is the technique photographers, designers, and artists use to create the illusion of three dimensions on a flat or two-dimensional surface. The status bar of the document window shows the current document size. Marquee tools are useful when the part of an image or photo that you wish to select fits into rectangular or elliptical shapes. The New selection button allows you to start a new marquee. To activate the Subtract from selection button, you can click it on the options bar or hold down the ALT key while dragging.

5 If you press the ALT key while drawing a selection using a tool shown in the figure above, the marquee is created from the center. The Single Row Marquee tool shown in the figure above allows you to select a single row of pixels. Pressing SHIFT+ALT while drawing a selection using one of the tools in the figure above starts from the center and constrains the proportions. If you press the SHIFT key while dragging a marquee using one of the tools in the figure above, Photoshop creates a perfect square or circle from a shape. To activate the Add to selection button, you can click it on the options bar or hold down the SHIFT key while dragging a second selection. Selecting the inverse means selecting everything in the image except the previous selection. On the Style box arrow, the Normal style sets the selection marquee proportions by dragging. On the Style box arrow, the Fixed Ratio style sets a height-to-width ratio using decimal values. When using the Rectangle Marquee tool or the Elliptical Marquee tool, you can click the Style box arrow to choose how the size of the marquee selection is determined. When the Refine Edge button is clicked, it opens a dialog box in which you can make adjustments to how the edge is selected, by changing the contrast or the radius of the marquee, or by smoothing the selection border.

6 As shown in the figure above, feathering softens the edges of a selection. In traditional photography, the effect shown in the top right of the above figure is called vignetting. When using the Elliptical Marquee tool, you can further specify blending by selecting the Anti-alias check box to adjust the block-like, staircase look of rounded corners, resulting in the effect in the bottom-right corner of the above figure. If you delete a selection by accident, press CTRL+Z to bring the selection back. A layer is a portion of the image that is superimposed or separated from other parts of the document. Activating the Move tool by pressing the V key on the keyboard allows you to move the selection border and its contents by dragging them in the document window. Available on the Move options bar, the Auto-Select check box is used to select layer groupings or single layers. The Magic Wand options bar has a Tolerance box that allows you to enter a value that determines the similarity or difference in the color of the selected pixels. When you use the Magic Wand tool and click in the image, Photoshop selects every pixel that contains the same or similar colors as the location you clicked.

7 When you choose to transform or when you click the Show Transform Controls check box on the Move options bar, Photoshop displays a bounding box like the one in the accompanying figure. As shown in the accompanying figure, a small reference point is displayed in the center of a selection when you choose a transformation. To choose a transformation command, click the Edit menu, point to Transform, and then click the desired transformation. Using the mouse in conjunction with the Skew command on the Transform options bar allows you to drag a side of the bounding box. Using the mouse in conjunction with the Distort command on the Transform options bar allows you to drag a corner sizing handle to stretch the bounding box. To display the Transform options bar, create a selection and then press CTRL+T. After you are finished making transformations, you commit changes by pressing the ENTER key or clicking the commit button, which is a checkmark at the top right. On the left side of the Transform options bar, Photoshop displays the Reference point location button; each of the button s nine squares corresponds to a point on the bounding box. When you click the Maintain aspect ratio button on the Transform options bar, the aspect ratio of the selection is maintained. On the Reference point location button, the middle square is selected by default. The History panel records each change or new state of the file on which you are working.

8 Each time you apply a change to an image, the new state of that image is added to the bottom of the History panel shown in the figure above. By default, the panel in the accompanying figure lists the previous 20 states. If you select a state and change the image by accident, you can use the Undo command on the Edit menu to restore the eliminated states. You can give a state a new name called a snapshot. The term snapping refers to the ability of objects to attach, or automatically align with a grid or guide. When a layer is as shown in the figure above, you can see through it to the layers below.

9 Unlike the layer shown in the figure above, opaque layers are solid and eclipse lower layers. On most layers, the Eraser tool simply erases the pixels or changes them to transparent, as shown in the figure above. Layers can be copies, merged with other layers, or flattened into one layer. A layer is a section within a Photoshop document that you can manipulate independently from the rest of the document. As shown in the two figures below, a hollow lock indicates that a layer is partially locked.

10 The Panel Options command allows you to change the view and size of the small preview corresponding to each layer on the Layers panel, as shown in the above figures. As shown in the accompanying figure, a thumbnail is a small visual preview of the layer on the Layers panel. The name of the active layer displays on the title bar in Photoshop. If you have more than seven layers the number of reserved colors for coding layers you can group layers that have similar characteristics with one color. White is NOT a color that Photoshop reserves for color coding layers. Layer groups help you manage and organize layers in a logical manner. The Anti-alias check box creates a smooth edge that can apply to both selecting and erasing. To turn the visibility for layers on and off, you can press ALT+click on the visibility icon for the layer you wish to view. The Eraser tool options bar displays a Mode box in which you can choose a shape for erasure. The Eraser tool options bar displays an Opacity box in which you can specify the depth of the erasure. The Eraser tool options bar displays a Flow box in which you can specify how quickly the erasure is performed. A mask is used to show or hide portions of a layer or protect areas from edits. A layer mask is a grayscale image, which means each pixel in the mask is represented by a single sample value.

11 To cancel a selection like the one shown in the accompanying figure, you can press the ESC key. You can press the CTRL + Z key(s) to undo an erasure. To access the eraser tools after using a different tool, press the E key. A higher tolerance erases pixels within a broader range of color values similar to the selected pixel. The ] key on your keyboard is used to increase the size of the eraser. The three sampling buttons found on the Background Eraser Tool options bar are used to erase colors continuously as you drag, only the areas containing the color you first click, and only areas containing the current background color. Vector masks are resolution independent and are created with a pen or shape tool. To create a layer mask, Photoshop provides an Add layer mask button on the status bar of the Layers panel. Pressing the B key on the keyboard will activate the brush to paint in a layer. If you make a mistake while creating a mask, you can press the X key on the keyboard to toggle to the default foreground color and paint to unmask the error. You can duplicate a layer by right-clicking a layer on the Layers panel, and then clicking Duplicate Layer on the shortcut menu. Tonal adjustments affect the tonal range of color, lighting, opacity, level, or fill. Style adjustments include special effects or blends. Filter adjustments let you apply predetermined pictures, tiles, or patterns.

12 A level adjustment is one way to make tonal changes to the shadows, midtones, and highlights in a layer or to the entire image. A pattern is an image that is repeated when you use it to fill a layer or selection. A flattened file is easier to work with, as far as printing, displaying it on the web, or exporting it to other uses. If you flatten an image and then change your mind, if the file still is open, you can click the previous state on the History panel to restore all of the layers. When working with composite objects, to maintain the integrity of each element and to provide maximum flexibility in future editing, it is a good idea to save the file in PSD format. A raster image is a digital image represented by a matrix of pixels. Because TIF files are supported by virtually all paint, image-editing, and page-layout applications, it is a versatile format for cross-platform applications. When setting the resolution of an image, you can specify the number of pixels per inch, or per centimeter. CMYK images use 33 percent more file space than RGB images. A color mode determines the number of colors and combinations of colors used to display and print the image. Each color mode uses a numerical method called a color space, which describes the color. A gamut is the range of colors that can be displayed or printed. In Photoshop, you will see an out of gamut warning if you select colors that have to be converted from RGB used in editing, to CMYK used in printing. Three basic parameters make up the LAB color mode: lightness of the color, the color's position between magenta and green, and the color's position between yellow and blue. RGB is considered an additive color mode because its colors are created by adding together different wavelengths of light in various intensities. When converting to Indexed color, Photoshop builds a CLUT, which stores and indexes the colors in the image. The Indexed color mode is a color mode that limits the panel of colors in order to reduce file size yet maintains some visual quality. Given a bit depth of 8 in a given color mode, Photoshop assigns 8 binary settings for each color. CMYK is ideal for print media. Photoshop s CMS translates color from the color space of one device into a device-independent color space. The process of translating colors from the color space of one device into a device-independent color space is called gamut mapping. The word bit stands for binary digit. A printing press can reproduce about 50 levels of gray per ink. Hexadecimal is a numbering system based on groups of 16.

13 The background color commonly is used with fills and masks. A colorcast is a shade in a photo that should not exist. Use black backgrounds sparingly they are most effective for starkness and special effects. Created using the options bar in the accompanying figure, the Radial gradient style creates shades from the starting point to the ending point in a circular pattern. Available on the options bar in the accompanying figure, the Angle gradient style creates shades in a counterclockwise sweep around the starting point. On the right side of the Gradient options bar shown in the accompanying figure, Photoshop includes a Dither checkbox to create a smoother blend with less banding. One hundred percent as a smoothness setting for a gradient indicates an equally weighted transition between color pixels. If Photoshop displays an exclamation point inside a triangle in the dialog box in the accompanying figure, it means that the chosen color is out of gamut, meaning it is out of range for the color settings. You use the Only Web Colors check box shown in the dialog box in the accompanying figure to only display only those 216 colors that appear solid, non-dithered, and consistently on any computer monitor. The dialog box in the accompanying figure can be used with various tools to set target colors such as gradients, fill layers, and filters. To constrain a line angle to a multiple of 45, hold down the SHIFT key as you drag.

14 As you create a gradient, the rate of transition is dependent on the settings in the Gradient Editor dialog box with its color stops and midpoint. The Eyedropper tool samples an existing color in a graphic or panel to assign a new foreground or background color. Pressing ALT+click on the Eyedropper Tool button on the Tools panel assigns the color to the background. Sampling a color (with the Eyedropper tool) guarantees that you will match the color without having to reenter color values on the Colors panel. A typeface defines the appearance and shape of the letters, numbers, and special characters used in text. If you create a shape and later decide it should be larger or smaller, simply press CTRL+T to display the shape s bounding box, resize the shape by dragging the sizing handles and then press the ENTER key. With respect to lines, Photoshop allows you to set several options: the thickness of the line, the concavity of the arrowhead (how indented it is), and the length of the line. To view the Info panel, you can press the F8 key on the keyboard. The Info panel displays information about the color values beneath the mouse pointer and other useful information depending on the tool that you use. Photoshop uses a percentage value, called hardness, to denote how solid the edge of the brush stroke is displayed. Pressing the SHIFT key while dragging with a brush creates straight lines, freehand. If you make changes to a preset brush size, shape, hardness, etc. - the change is temporary.