Image Scanning Basics with Adobe Photoshop Elements 4.0 Project I. A Simple Scan
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Project II. Common Image Enhancement
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Project III. Color Changes, Bleed-Through Background Removal
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Project IV. Layers, Erasing, Adding Text
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Project V. Portrait Enhancements
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Project VI. Insert Images into PowerPoint
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Project VII. Scanning 35mm Slides
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Project VIII. Solo Practice Exercise
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Resources:
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Image File Formats
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Glossary of Scanning Terms
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Online Information
University of Virginia Claude Moore Health Sciences Library 1 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Notes:
University of Virginia Claude Moore Health Sciences Library 2 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Introduction All brands of scanners come with their own software programs that operate the scanner, enabling it to communicate with the computer. These scanning software programs operate as a “plug-in” inside a graphic enhancement program like Adobe Photoshop. Scanning can be done directly from Microsoft word or PowerPoint also (versions 2000 and up). The scanning software program is often referred to as the “TWAIN” program. In this class we will work with the Epson TWAIN inside Adobe Photoshop Elements 4. The class is constructed as a series of hands-on projects which demonstrate common scanning and enhancement skills.
Image Copyright Information Scanning images from books or journals and downloading images from the Web are common practice. Be aware that almost all images are copyrighted, whether or not they have copyright information on them. Asking permission for using images is the only way to insure that you are not abusing the privilege of using images created by someone else. Some publishers and authors are agreeable to the use of images “for educational purposes”, but checking with the publisher or author first is advisable. Always give credit to the source of the image in your presentation. Information about the University of Virginia’s copyright policy can be found here: http://www.lib.virginia.edu/acquisitions/copyright/
University of Virginia Claude Moore Health Sciences Library 3 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Project I: A Simple Scan Objectives: • Choose the correct scanning software settings for different types of images; photographs, document or film. • Choose the appropriate file type to save your scanned image according to its planned use. • Identify the different parts of the Photoshop Elements desktop. A. Preview the image scan: 1. Open the Adobe Photoshop Elements 4.0 program: From the Start button, select Programs > Adobe Photoshop Elements 4. 2. Place your image to be scanned face down, aligned with the upper right hand corner of the scanner bed. 3. Adobe Photoshop Elements: select Start from Scratch from the opening dialog box. 4. Click Cancel on the dialog box. 5. From the File menu select Import > Epson Perfection 4180. 6. Click the Preview button to pre-scan your image. B. Choose scanner settings for your image: The following settings are recommended for color photographs for PowerPoint. Options for other types of images, as well as a screen capture of the TWAIN settings window, are on the following page. 1. Document Type: Photo 2. Image Type: 24-bit Color 3. Target Size: Original 4. Resolution: 96 dpi C. Save your image 1. From the File menu choose: Save As 2. Choose location you will save the file: Save In 3. Type name of the image file: File Name 4. Choose the appropriate image file type: Format. The most commonly used formats and their uses are: • JPEG file format for images going to the web, PowerPoint, e-mail attachments • TIFF file format for images to be printed • PSD file format for images you plan to work with again in Photoshop (this file format is only compatible with Adobe Photoshop).
University of Virginia Claude Moore Health Sciences Library 4 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
TWAIN Settings Dialog Box Professional Mode should be selected Original Document Type choices: • Reflective for images on paper (photo, journal, book etc.) • Film for 35mm slides or film negatives. Document Source: • Document Table for images on paper. • Positive Film, Color or B&W Negatives for 35mm slides or film. Auto Exposure Type: • Document for images on “plain” paper or • Photo for photographs (hi-quality paper) • No choice for Film Destination Image Type: • 24-bit color for color film or paper images • 8-bit Grayscale for black & white images or film Resolution: • 72-96 dpi for images to be viewed on a computer monitor (PowerPoint, Web, e-mail) • 300 dpi (or higher) for images to be printed >Draw a marquee around image area to be scanned. This cropped area can be viewed larger by clicking the Zoom button. Document Size: • Width and Height of cropped image given in inches, millimeters. Target Size: Original scans the image at 100%. To change the size of the image, click the + button next to Target Size. You can select a preset size from the list under Original, or use the sizing feature to increase or decrease the size of your image. Adjustments: • Click on the tools to make corrections in contrast, brightness, colors. These types of adjustments can also be done in Photoshop Elements. Scan your image when ready by clicking the Scan button. Your scanned image will appear in the Photoshop Elements program. Close the Epson Scan program.
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To preview your image, click the Preview button. To view your image enlarged, click the Zoom button in the Preview window.
University of Virginia Claude Moore Health Sciences Library 5 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Image Types and Suggested Scanning Resolutions. Image Type
Image Type Selection
Resolution for Print
Photograph
Color or Grayscale Photo
300 dpi
Magazine or Book
Document: Color or Grayscale
300 dpi
Text without images
Black & White Document
Resolution for PP, Web, E-mail 72-96 dpi
300-400 dpi
Set dpi to 300-400. Use Adobe Acrobat or ABBYY FineReader for best results with text scanning
Text with images (black & white/grayscale)
8-bit Grayscale
300-400 dpi
Text with color images
24-bit Color
300-400 dpi
Film Scanning
Film Type - Image Type
35 mm slide – color
Positive - 24-bit Color
35mm slide – grayscale
Positive - 8-bit Grayscale
Increase target size as needed.
Increase image target size 400% or more
Gel stains, x-ray – grayscale
B&W Negative – 8-bit grayscale
300 to 2400 dpi
72-96 dpi
Color Negative – 24-bit Color
Increase image target size as needed.
Increase image target size as needed.
Color negative film
University of Virginia Claude Moore Health Sciences Library 6 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Resolution for Print 300 dpi*
Resolution for PP, Web, E-mail 72-96 dpi
Project II: Common Enhancements Objectives: • Use a series of tools and commands to enhance and manipulate a photograph. • Change the Options for each tool selected. • Change from Standard Edit Mode to Quick Fix and use the tools in both. • Rotate, crop, and correct an image.
The Adobe Photoshop Elements 4.0 Desktop Menu Bar
Shortcuts Bar
Option bar (changes with each tool in use) Toolbox
Palette Bin
Screen Orientation Menu bar contains menus for performing tasks. The menus are organized by topic. Shortcuts bar displays buttons for executing common commands like “Open File”. Options bar provides the options for using the selected tool from the toolbox. Toolbox area holds tools for selecting, editing and viewing images as well as tools to let you paint, draw and type etc. Pass your mouse cursor over each tool to see its name. Tools with a small triangle beneath its icon have additional “hidden” tools, click on the triangle to view them. To use a tool, click on its icon then make adjustments in the Options bar if necessary. The options bar changes as you select different tools. Some options are common to several tools, and some are specific to one tool.
University of Virginia Claude Moore Health Sciences Library 7 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
A. Open the first image: 1. From the File menu select > Open > C: drive > Image-Scan Class folder > Spain. 2. Click the Maximize icon to enlarge image, making it easier to work with. B. Rotate an image: Sometimes it is necessary to scan an image sideways or even upside-down to make it fit onto the scanner flatbed. It is easy to correct the angle of the image using the rotate command. 1. From the Image menu select > Rotate > 180o 2. Images can also be adjusted in 1% increments using the Custom feature under Rotate. C. Crop an image: 1. Click on the crop tool and move your cursor over the image. Hold down the left mouse button and drag a marquee around the area you want to keep. Drag the sizing handles while holding down the left mouse button to make adjustments to your crop marquee. 2. Double click inside the cropped marquee area to select it and discard the rest. D. Undo changes: 1. Click on the Undo button that is located on the Shortcuts Toolbar. Undo multiple changes by continuing to click this tool. E. Use the Clone Stamp tool: With this tool you can easily retouch damaged areas of images. The tool takes a sample of the spot you select and applies that sample to another area of the image. Click on the Clone Stamp tool. You have two choices: clone stamp or pattern stamp tool. Options we will use today: 1. Clone stamp takes a sample of the area you click on while hold down the Alt key (Command key on a Mac). 2. Size the brush by pixels using the slider bar. 3. Opacity is the depth of color, value from 1% to 100%. The higher the number, the deeper the color. 4. Aligned: when this box is selected or checked, the sampled area moves along in the same direction as you click the stamp tool. Uncheck the box to keep the sample spot stationary, picking up the same spot over and over. Make sure the Aligned option is deselected (unchecked) for this exercise. To cover up the date stamp on this image using the Clone Tool: 1. Hold down the Alt key and click on a “good area” of the image next to the date stamp (not on it) to copy it into the tool’s memory. 2. Let go of the Alt key. 3. Left mouse click over the time stamp to cover it up with a “cloned” image of the good area. The date stamp disappears!
University of Virginia Claude Moore Health Sciences Library 8 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
F. Select an image area using the Magic Selection Brush tool 1. Click to select the Magic Selection Brush Tool 2. Draw a wavy line across the sky above the buildings. The sky area will become selected. 3. To adjust the selected area, use these Section buttons; Add To or Subtract From
G. Change from Standard Edit to Quick Fix Mode 1. Click on the Quick Fix button to access a different set of tools. 2. Experiment with the Color and Lighting palettes to change the selected sky area. 3. Click on View: Before and After Landscape. You will be able to compare the changes as you work. 4. Press the Ctrl and D keyboard buttons to deselect the sky area. 5. Use the Lighting and Color Palettes to change the look of the entire image. 6. Click back into Standard Edit Mode when finished.
Project III: Change Image Colors Objectives: • Identify and correct bleed-through for an image by matching colors and refilling shapes and background. • Use two different methods for choosing colors. For the set of exercises, from the Image-Scan Class folder, select substrate enzyme complex.psd A. Change a color or background There are two methods for selecting colors: 1. Select a new color from the Color Picker Palette: a. Double click the Set Foreground Color box b. Click a color area to select it. c. Move the slider up and down to find different ranges of color. or 2. Match an existing color within the image, using the Eyedropper tool a. Click on the Eyedropper tool to select it. b. Click on a clean area within the pink shape to select its color. Note the color changes to the same shade of pink in the Foreground Color Sample box.
University of Virginia Claude Moore Health Sciences Library 9 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
2. Click on the Magic Wand tool and click within the pink area of the shape. The pink area should now be outlined with a moving dashed line. 3. Click on the Paint Bucket tool in the shape, removing the bleed
and click inside the pink shape. The solid pink color will fill through text.
4. Repeat the process to replace the white around the shape with pure white and the green shape. You can choose a color from the Color Picker pallet or use the Eye Dropper tool.
Project IV: Layers, Erasing, Adding Text Objectives: • Use the Eraser tool to erase part of the image. • Identify the options of each tool used. • Correct the bleed through text as learned in Project III. • Use the Text tool to type new text on the image. • Layer a second image on top of the first. For this set of exercises, open the image Reconstruction of Bone Shape grayscale image from the scan class folder. 1 2 3 A. Erase portions of an image: Click on the Eraser tool. It has three modes: 1. Eraser tool 2. Background Eraser 3.Magic Eraser
The Eraser tool (1) lets you erase to the background color in a background layer. The Background Eraser (2) and Magic Wand Eraser (3) are for working with different layered images. Information about using these tools is available in the Help menu. 1. Click to select the Eraser tool (1) in the toolbox. The other options for the eraser are: • Brush styles: Leave the setting at Default Brushes. • Size: set the tool size by number of pixels, from 1 to 2500 pixels . • Mode: choices include brush, pen or block. Select Block, which changes the shape of the eraser to square. • Opacity: values from 1% to 100%. Choose 100% (the complete erasing of an image area). 2.
Using the Block Eraser, drag over the text to erase it. If your eraser color is not white, click on the Switch Foreground and Background Colors double headed arrow.
B. Bleed-through text removal Remove the bleed-through background as in Project III. 1. Use the Eyedropper tool to select the exact white color in the erased area. 2. Use the Magic Wand tool to select the white background with bleed-through text. 3. Use the Paint Bucket to whiten the entire background to the same shade of white.
University of Virginia Claude Moore Health Sciences Library 10 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
C. Add Text 1. Click on the Text tool Set the options for using the Text tool: • Type styles: choose from Regular, Italic, Bold and Bold Italic. • Type direction: either horizontal or vertical. • Font style: select one from the drop down list. • Font size: choose 14 point for this project. • Anti-aliased: feature is either on or off. Selecting it produces smooth-edged type by partially filling in the edge pixels. • •
o Click to activate it. Text alignment icons: for left, centering or right alignment of selected text. Text color selection: for changing the color of text. Black and white or grayscale images must first be changed to RGB mode before color (other than black, white or grey) can be added to text. To change from B&W to RGB mode, select the pointer tool, then from the Image menu, select > Mode > RGB. Now you can create type in color. o Click on the Color Picker box in the Text Options bar at the top of the window. o Choose a color.
2. When you’ve set the Text Tool options, click on the image with the Text Tool still selected (it looks like an I-beam) and type Reconstruction of Bone Shape. Press the Enter key to exit text editing mode. in the Toolbox. Hold down the left mouse button while dragging 3. Click on the Move tool the text box to the desired location. To change the text size, color etc., select the text first by holding down your left mouse button and dragging over the text to highlight it. Use the text box sizing handles to change the size and shape of the text.
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4. Warping Type: choose a text shape from the dropdown menu. 5. Text Orientation: text can be displayed either vertical or horizontal. D. Layers: making two or more images into one 1. Select the Move tool 2. From the Scan Class folder, select Bone Insert. It will appear on the desktop. 3. Click the Tile Images icons in the upper right corner. Both the Bone Insert and Reconstruction images will be displayed simultaneously on the desktop, or “tiled”.
4. Using the Move tool, hold down the left mouse button on the Bone Insert image and drag it slowly onto the Reconstruction image. You should be able to move the small Bone Insert image anywhere you choose by holding down the left mouse button and dragging the image. 5. Close the Bone Insert image window, and maximize the Reconstruction image. Examine the Layers Palette on the right side of the Elements desktop. You will have three layers now; Background, Text, and Bone Insert. If you have difficulty editing something in one of the layers, make sure the correct layer in the palette is active, or selected. University of Virginia Claude Moore Health Sciences Library 11 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Project V: Portrait Enhancements Objectives: • Remove the red eye effect from man in photograph. • Use the Healing Brush tool to improve skin blemishes. A. Red eye reduction: 1. Open the image > Red eye example.psd from our Scan Class folder. Maximize the window. 2. Enlarge photo using Magnifying tool Click + to enlarge minus to reduce image size. Or use the keyboard shortcut: Press Ctrl and + keys to enlarge image, Ctrl and – keys to reduce image size. 3. Click on the Red Eye Removal tool. 4. Click in the red area of an eye or draw a small selection marquee over one red eye. When you release the mouse button, the red is removed from the eye. To adjust the effect, drag the Pupil Size and Darken Amount sliders in the Options Tool bar. 1. 2. B. Healing Brush enhancements The Healing Brush works very much like the Clone Stamp Tool. There are two variations of the tool: o Spot Healing Brush – set the size of the tool then click on the spot you want to improve. It automatically matches the spot it covers with a clone of a nearby area. o Healing Brush – this tool works just like the Clone Stamp tool; hold down the Alt key and click to select the background spot you want to clone to cover an area or spot with.
Project VI: Insert Images into PowerPoint Objectives: • Insert scanned images onto PowerPoint slides. • Use image sizing handles to resize image. A. Insert images into PowerPoint 1. Open PowerPoint from the Start then > Microsoft Office 2003 PowerPoint 2. Select Insert a New Slide. Choose a blank slide from the Contents choices. 3. To bring in the first image: from Insert select > Picture > From File. In the Look In dialog box, choose the location of your image files, the Scan Class folder. Select an image file and click Insert. The image appears on the blank slide. It may be sized by dragging the sizing handles from a corner of the selected image. Sizing from the corner will keep the image proportions correct. 4. Repeat Steps 2 and 3 for each additional scanned image you wish to insert onto a slide.
Project VII: 35mm slide scanning Objectives: • Set up scanner for slide scanning. • Choose correct TWAIN settings for scanning slides. • Scan the slide into Photoshop Elements. University of Virginia Claude Moore Health Sciences Library 12 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
A. Set up the scanner 1. Remove the reflective mat from the scanner lid and set aside. 2. Place the 35mm slide holder on the glass flatbed. 3. Place slides into the holder frame “glossy” side down (usually side with printing). Close the scanner lid. 4. Open Photoshop Elements 4.0 and start the scanning program the same way as in Project I: A Simple Scan on page 4. •
Mode: Professional Mode
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Document Type: Film
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Film Type: Positive or Negative
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Image Type: -Color Slides: 24-bit Color -Black&White slides: 8-bit Grayscale • Resolution: -72dpi for PowerPoint, e-mail or web images. -300dpi or more for print > When you get to this point, click the Preview button at the bottom of the menu to pre-scan your image. > Draw a crop box around the aea of yur prescanned image. Hold down the left mouse button over the image and drag to draw the box. • • • • • • • • •
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Document Size: shows actual image size in either inches, pixels or millimeters. Target Size: -Adjust % amount higher or lower depending on the image dimensions you need. Trimming: On (a tiny amount is trimmed off edges) Preview button: click this button to pre-scan your slides. See the next page for Preview information. Adjustments: click on these tools to make enhancements to color, brightness & contrast etc. Unsharp Mask Filter: check this option to sharpen image. Click the + button to choose level of sharpness; low, medium or high. Grain Reduction: leave unchecked Color Restoration: check this option if your slide is faded, if you don’t like the change, uncheck it. Dust Removal: if your slides have dust or lint, check this option. Select the level; low, medium or high. You will not see any change in the preview window, just in the scanned image. Scan: click the scan button to scan the selected image. For multiple slide scanning, see the next page for instructions. See the next page for information on Previewing, rotating, cropping, enlarging image view and scanning multiple slides at once.
University of Virginia Claude Moore Health Sciences Library 13 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
B. Preview and select slides to scan 1. Click the Preview button to see thumbnail images of your slide(s) in the Preview screen. 2. Click on an image to select it. A blue frame will appear around the selected image, and a checkmark in the box next to the number. Rotate or reverse the images by using the Frame buttons. Click the Full Size tab to enlarge image view and draw a marquee crop box.
3. Each image is numbered. Click the check mark button to select or deselect the image for scanning. C. Scan one slide at a time 1. Draw a marquee crop box around the area to be scanned. 2. Enlarge the scale/size of the film image in the Target tool in the TWAIN software using pixels or inches as measurement. 3. To scan the slide image, make sure you are in Thumbnail view and the other images are unchecked. 4. Click the Scan button to scan your slide image and place it into Photoshop Elements. 5. Click the Close button if you are finished scanning. 6. To scan more slides, draw a marquee crop box around the next slide image. Make sure the other slides are unchecked. 7. The scanned images will appear in the “photo bin” of Photoshop Elements. Click on an image in the bin to select it for further enhancements or saving. For more information on different file types and their uses, see the File Types guide in the last section of this manual. University of Virginia Claude Moore Health Sciences Library 14 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
D. Scan multiple slides at a time 1. 2. 3. 4.
Draw a marquee box around the slide and choose the settings for it. Be sure the slide is checked. Repeat step 1 for up to 4 slides. Click the All button in the Preview pane. Click the Scan button and all checked slides will be scanned with the settings you chose for each slide.
Project VII. Solo Exercise Objectives: • Use a series of tools to complete the edits and enhancements to the Beachscene image. • Refer to correct manual pages for help, when needed, to use the tools. For this exercise we will open and use the image Beachscene in the scan class folder. 1. Using the Crop tool, remove the branch stub area (far left) of the photo. Remember to draw the marquee around the area you want to KEEP, the rest will be deleted. (pg. 8 of manual) 2. Use the Clone Rubber Stamp tool to change the black pencil area back into the ocean color. (pg. 8) 3. Use the Text Tool to add a heading “Grand Cayman”. Make the text a blue color, and size it. (pg. 10)
From this…..
University of Virginia Claude Moore Health Sciences Library 15 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
To this!
Resources Consultations: this library offers one-on-one consultations on PowerPoint, scanning, and many other subjects. Please call the LRC Desk for an appointment at 924-5521. For more information about the services and classes the Health Sciences Library offers, check out our Web page and click on Library Classes. http://www.healthsystem.virginia.edu/internet/library/
Image file formats GIF, JPEG and PNG are graphic file formats that are common in Web development because they can compress the images’ file data and size for faster travel across the Internet. File size is an important consideration when saving scanned images to a floppy disk for a PowerPoint presentation. Two types of compression are available: lossless and lossy. Lossless file formats compresses image data without loss of data and includes TIFF, PNG and GIF file formats. Lossy compression offers even greater file compression, but some file data is lost causing minor loss of image quality. Often this loss is not even noticeable. Below are descriptions of the most commonly used file formats today.
GIF: (Graphics Interchange Format) A good lossless image compression format. The GIF format is best used for cartoon-like graphics, logos, text, and graphics with transparent areas, animations and movies. Compressed GIF images are usually larger than JPEGs. GIF is not the best format for images that have a range of subtle color changes such as photographic portraits.
JPEG: (Joint Photographic Experts Group). A lossy image compression format, also the most popular, efficient and essential compression format currently available. The color range is up to 16 million colors. Jpeg (.jpg) compression does “throw away” colors the image is not using, producing very small, but good quality images. Commonly used for web/computer and projector screen viewing. Jpegs are usually fine for printed images also, unless high quality is desired. JPEG format is best used for scanned photographs, images using textures, images with gradient color transitions, or any images that require more than 256 colors.
PICT: (Picture). A Macintosh-based format for storage and exchange of graphic documents, containing bitmapped and/or object-based images. PICT should be used for screen display only.
PNG: (Portable Network Graphics). Pronounced “ping”. A lossless file compression format. This is the native format of Fireworks. PNG does not compress files as much as JPEG. Best used for onscreen presentations such as PowerPoint, Macromedia’s Director or Authorware.
TIFF: (Tagged Image File Format). A good, versatile, lossless file format for page layout, image editing, illustration and word processing programs. Probably the most widely used bitmapped file format. There are MAC and PC versions of TIFF. TIFF version 4.0 is the most compatible, while version 5.0 offers added compression and higher bit depths. The 6.0 version specification allows for high fidelity color and even greater compression. The numbers after TIFF, refer to the bit depth.
University of Virginia Claude Moore Health Sciences Library 16 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
Glossary of scanning terms
BIT: binary digit. The basic unit of information that all computers use to manipulate data. The value of a bit (0 or 1) represents a two-way choice, such as yes/no, on/off or black/white.
BIT DEPTH: The amount of tone data per sample expressed in number of bits. Typical bit depths are 1 (for line art), 8 (for grayscale or black and white images), and 24 (for color images).
BITMAP: originally a term used to describe a memory model where each bit in screen memory was “mapped” to a corresponding screen pixel, hence the bitmapped. Today it is used universally to describe all types of pixel-oriented displays, from 1 bit (true bitmapped) to grayscale (8 bits per pixel) to full color (16 or 24 bits per pixel).
BYTE: a computer term equal to 256 levels of information. Also, the number of bits used to represent a character. One byte equals 8 bits. A standard unit of measure for file size.
DESCREENING: the technique of eliminating moiré patterns when scanning. A moiré pattern is an undesirable interference pattern in color printing of resulting from misaligned or improper screen angles. Also created when previously halftone images are scanned.
DITHERING: a technique of using patterns of dots or pixels to create the effect of an intermediate tonal value.
DPI: Dots Per Inch. A measure of the output resolution produced by a printer. A laser printer with 600 dpi prints 600 dots per inch. See SPI for an explanation of this term used for data measurement of scanned images, not to be confused with DPI!
EXPOSURE: the overall brightness of an image resulting from a combination of time and intensity of light allowed to the film.
FILE: a named collection of binary information stored as an apparent unit on a secondary storage medium such as a computer disk.
FLATBED SCANNER: a popular type of desktop scanner so called because of its glass platen or “bed” upon which originals are placed to be scanned.
GRAYSCALE: a continuous tone image made up of a number of shades of gray.
HALFTONE: a technique of converting a continuous-tone (grayscale) image into variable-sized spots representing the individual tones of the image. The process creates a printable version of a photograph. For example, the photographs in newspapers have been converted into halftones before being printed.
JAGGIES: the pixilated or stair-step appearance of low-resolution computer generated graphics.
LINE ART: images made up on only pure black and white data. Also a mode of capturing such images.
University of Virginia Claude Moore Health Sciences Library 17 Scanning & Enhancing Images with Adobe Photoshop Elements 4.0
PIXEL: Picture element. One of the individual elements that make up a video monitor’s image area. Typical monitor pixel resolutions are 640 x 480, 800 x 600, and 1,024 x 768. PPI or Pixels Per Inch is the frequency of the number of samples used to display an image on a computer monitor.
RESOLUTION: indication of how finely an image is resolved into pixels. Measured in dots per inch (DPI), pixels per inch (PPI), or samples per inch (SPI). The higher the number of dots, pixels, or samples the better the resolution. High-resolution numbers also create larger file size.
SPI: (Samples Per Inch). A “Sample” is the smallest discrete amount of data captured by a scanner. Expressed in Bit Depths of 1, 8, or 24 bits. SPI refers to the number of image data samples captured per inch, as opposed to the terms DPI or PPI, which are measurements of output.
THRESHOLD: the tonal value, used when scanning line art or converting grayscale images to bitmapped, above which is rendered white and below which is rendered black. Typically expressed in percentage of gray.
TWAIN: Technology Without An Interesting Name (urban legend?) TWAIN is the name often given to the software that operates the scanner. TWAIN operates from within a “host application” which supports it, such as Photoshop, Fireworks, Microsoft Word or PowerPoint.
UNSHARP MASKING: also know as USM. A technique of accentuating the contrast at border areas of significant tonal difference within an image.
Web sites Download Adobe Photoshop Elements for a free tryout: http://www.adobe.com/downloads/ A website for more information about scanning: www.scantips.com Sources for medical images can be found from the Health Sciences Library’s Webpage: http://www.healthsystem.virginia.edu/internet/library/services/howdoi/
Purchase Information Adobe Photoshop Elements 4.0 can be purchased from Cavalier Computers at the educational discount price.
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Revised 8-16-06
