Using Photoshop s GUI


A Graphical User Interface or GUI (pronounced gooy) is a software program s way of communicating with you. The computer is really not much more than a machine that does really fast math, and each operation is a series of mathematical calculations. Imagine how labor- intensive it would be if you had to perform that math yourself. For example, suppose you had to change the RGB values of the pixels in 1 square inch of an image to be printed in a magazine. You would have to perform 90,000 calculations by hand. Talk about mathaphobia! Fortunately, software designers have set up an environment ”the GUI ”that makes it easy for you to perform complex calculations quickly and without even having to add 2 + 2. In fact, when you work in a program such as Photoshop, the GUI is so seamless that when you change the color of pixels, it feels as though you re working in a studio environment.

Photoshop s GUI is easy to use after you learn what the tool icons, menus , and floating palettes represent and how they perform. The Photoshop GUI provides tools and operations that are used by many professionals who work with images, including designers, architects , photographers, artists , printers, and scientists. These virtual tools simulate the processes and operations performed by their real-life counterparts, and furnish a comfortable, familiar working environment.

The Photoshop interface, as shown on Mac OS X, looks like Figure 4.3. The Tool palette is displayed on the left side of the screen, and four palette clusters are displayed on the right side. At the top of the screen are the menus. From these three areas, you will access all of Photoshop s image-editing tools and operations.

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Figure 4.3: The Photoshop workspace in Mac OS X, showing default settings

Touring the Image Window

When you open or create an image, it is displayed in the image window (shown in Figure 4.4). To change the window s size , place your cursor on the lower-right corner, click the mouse button, and drag while holding it down.

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Figure 4.4: The image window labeled
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In the Windows interface, you can also enlarge or reduce any resizable window or palette by dragging any corner or edge.

To move the window, click the bar at the top of the window and drag. The scroll bars to the right and at the bottom enable you to scroll around images that appear larger than the size of the window.

The image window contains information about the document. The title bar gives the document s name , the percentage of the image s full size in pixels that you are viewing, the current layer and channel or mask, the color mode and the number 8 or 16 to indicate the image s bit depth. In the lower-left of the image window (on the Macintosh) or the Photoshop application window (in Windows) is the status bar. The leftmost field of the status bar shows, again, the view size as a percentage of the image, but this field is the magnification box where you can enter a specific percentage ”to the hundredth of a percent ”in which to view the image.

The second field at the bottom of the window shows, by default, two numbers divided by a slash, which is the document file size. The number to the left of the slash represents the base amount of uncompressed space that the file consumes on your disk, or the size of a flattened, uncompressed TIFF image. When you save the image in another format, the file size might shrink, because many formats use a compression scheme to consolidate data. The number to the right of the slash indicates the size of the image with the addition of any alpha channels, paths, spot color channels, or layers you might have created. The second number, of course, better represents the actual size of the image.

Getting Information about Your Documents

Photoshop has options that show you important information about your document, your computer, and the program s current state of operation. All of this information is useful in determining how efficiently your file will process and print.

Clicking the Status Bar

You can quickly view information about your document when you click the Status Bar.

Image Position Simply clicking the Status bar displays a diagram of the image as it will appear on the paper, as specified in File Page Setup (see Figure 4.5). Use this to ensure that the image will fit on your paper before you print it.


Figure 4.5: Click the Status bar to show the position of your image on the paper size that you designated in Page Setup.

Size and Mode Info Option-click (Mac) or Alt-click (Win) the Status bar to display the image s size, resolution, color mode, and number of channels.

Tile Info -click/Ctrl-click to display the tile sizes of the document. Photoshop uses tiles to display and process images. When you display an image or when the image refreshes, you can sometimes see the image appear progressively as it tiles on-screen. This window tells you the number of tiles comprising the image and is of little practical use to most users.

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CALCULATING FILE SIZE

A document s file size is calculated by multiplying its height and width in pixels by its bit depth, or the amount of memory each pixel consumes. For example, a full-color document that is 5 ³ tall by 7 ³ wide and has a resolution of 72 ppi (pixels per inch) is 504 pixels by 360 pixels.

Because the image is in full color, each pixel consumes 24 bits of space on the disk. For this information to be of use, you must convert it into bytes; there are 8 bits in a byte, so you divide 24 by 8 and get a factor of 3. You then multiply the height by the width by the bit-depth factor, or 504 — 360 — 3 = 544,320 bytes. Because there are 1024 bytes in a kilobyte, you divide 544,320 by 1024 to get 531.56, or 532 kilobytes when rounded off to the nearest whole number.

The value derived from this formula is the raw file size. The file size might be further reduced when the image is saved to an image format with a compression scheme such as JPEG, TIFF, or PSD.

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Clicking the Status Bar Pop-Up Menu

The status bar, by default, displays the current size of your document. But if you click the small black arrow at the right end of the bar, a pop-up menu enables you to select other information to be displayed:

Document Profile This option displays the name of the color profile with which the image was saved or assigned when opening. The color profile affects how the image appears on-screen (see Chapter 15). In the case of untagged images (an image without a profile), the word Untagged will appear next to the color mode of the file.

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Document Dimensions Here, the physical width and height of the document is displayed in the current units specified in the preferences.

Scratch Sizes The number to the left of the slash indicates the amount of memory needed to hold all current images open in RAM. The number to the right indicates the amount of memory Photoshop has been allocated (see the section on allocating memory in Chapter 5, Setting Up the Program ). Because of Photoshop s capability to record events in its History palette, the number on the left grows every time you perform an operation, as RAM is being consumed. (See Chapter 11, Altered States: History, to learn more about Photoshop s History features.)

Efficiency This option indicates what percentage of the last operation was performed in RAM. If this percentage drops below 80%, you might want to consider allocating more memory to Photoshop or installing more physical RAM. (See the section titled Allocating Memory in Chapter 5).

Timing If you select Timing, the information field tells you how long the last operation took to perform to the tenth of a second.

Current Tool This option displays the name of the currently selected tool.




Photoshop CS Savvy
Photoshop CS Savvy
ISBN: 078214280X
EAN: 2147483647
Year: 2004
Pages: 355

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