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Published byAmelia Atkins Modified over 9 years ago
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Digital Photo Correction & Manipulation Tonya Hines, CMI Certified Medical Illustrator Art Director, Mayfield Clinic
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Today you will learn Resolution What is dpi? How much resolution for specific uses File formats jpg, gif, tif, pdf, psd Which file format to use and why How to correct and manipulate Color photos Newspaper clippings Diagnostic scans (MRI, CT, angio)
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If you only learn 1 thing! Relationship of resolution and image size
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garbage in = garbage out Digital imaging Image capture: steps taken to digitize an image Image correction: steps taken to correct hardware interference with color and resolution Image manipulation: steps taken to artistically change an image for a desired effect
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Before you acquire images What is the final use of the image? On-screen/web (PowerPoint, MySpace, email, wallpaper, digital photo frame) Laser or inkjet prints (scrapbooks, handouts) Photo printing or publication Answer tells us Resolution and file size needed Best method to capture it shopping without knowing shirt size
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72 dpi 150 dpi What is resolution? Number of pixels per inch (blocks of color or gray that make a picture) More pixels per inch = higher res = more detail But also = bigger file size! pixel per inch (ppi)= dot per inch (dpi)
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Resolution & image size are directly proportional = 20 Mb file 8” x 10” 300dpi 41.6” x 33.3” 72dpi 2400 pixels 3000 pixels
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Resolution & image size are directly proportional 20 Mb file > 1.2 Mb file 8” x 10” 300dpi 8” x 10” 72dpi 2400 pixels 3000 pixels 576 pixels 720 pixels
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Why would I ever want small file size? Reduce system resources and time in processing and printing Too large to email as an attachment Fill up recipients email boxes (over quota) Maximize storage More resolution beyond your purpose is waste bigger is not always better Resolution is Height x width Dots per inch File size
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Resolution by usage/output Output or printerDPI needed Web72 Computer monitor96 Black and white laser printer150 Color inkjet printer150 - 220 Photo inkjet printer220 - 300 Newspaper100 - 150 Offset printing (brochures, books)266 - 350 don’t confuse image res with printer res
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Common resolutions Usagedpifile size PowerPoint 10” x 7.5” 96 1.98 MB Laser / inkjet prints 8” x 10” 150 5.15 MB Photo prints 4” x 6” 300 6.18 MB 5” x 7” 300 9.01 MB 8” x 10” 300 20.6 MB
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But I don’t know today all the possible uses of my image… 300 magic number 5 x 7 @ 300 dpi
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Problem with publication PowerPoint or web image 10” x 7.5” @ 96 dpi 1.98 MB Publication image 6” x 4” @ 300 dpi 6.18 MB can’t publish with web images
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When resolution is too low Scaling - doesn't change the number of pixels, just the resolution Height x width Dots per inch File size 4 x 6 300 dpi 6.18 MB 8 x 12 150 dpi 6.18 MB
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When resolution is too low Resampling - changes the number of pixels Downsample - delete pixels; cut file size Upsample - add pixels; increases file size upsampling doesn’t add detail = fuzzy 4 x 6 300 dpi 6.18 MB 4 x 6 150 dpi 3 MB 4 x 6 300 dpi 6.18 MB 8 x 10 300 dpi 20 MB very common interpolation
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If you only learn 1 thing! Relationship of resolution and image size BREAK?
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Capture devices Cell phone camera Point-n-shoot camera SLR digital camera Flatbed scanner Digital video camera
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Garbage in = garbage out Cell phone Point-n-shootSLR
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Image editing software Beginner Google Picasa free Adobe Photoshop Album free Mid-level - home / business use Adobe PhotoShop Elements$100 Corel Paint Shop Pro $100 Advanced - graphics professional Adobe PhotoShop CS3 $650 don’t buy CS3 - invest in a better camera
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Demos Portrait photos Remove red eye / flash reflections in glasses Too dark - too light Remove date stamp Landscape photos Straighten horizon line Remove telephone lines Group photos Diagnostic scans Newspaper clippings
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Image correction steps 1. Crop 2. Resize # of pixels 3. Adjust highlights and shadows (levels) 4. Adjust color balance 5. Sharpen filters 6. Save as appropriate file format (master) 7. Remove blemishes 8. Convert to grayscale or CMYK if appropriate 9. Save as appropriate file format (output version)
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Crop & resize # of pixels Crop tool No restriction Aspect ratio > select size (5 x 7 in) Image > Resize > Image size dialog box Resampling changes # of pixels
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Black point White point Tonal correction Histogram based on 256 levels of gray Black point (0) White point (255) Mid-range slider Enhance > Adjust lighting > Levels
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Color correction Color correct by adding or removing color complements
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About color management RGB sRGB CMYK
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Over sharpen = halo artifacts and aliasing Sharpening Filter > sharpen > unsharp mask Amount = ~ 100% Radius = 1.5 Threshold = 4
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Remove blemishes Eraser Clone Healing brush Red eye removal corrected
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Save - File formats Applications.jpg.gif.png.pdf.tif.psd PowerPoint XXXXX E-mail XXXX Website XXX InDesign XXX PhotoShop XXXXXX Word XXXXX Use compression
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File formats .jpg (joint photographic experts group) Compression options 1-12 Good for PowerPoint, web, and email Caution: repeated saves degrades image quality .tif (tagged-image file format) Most popular, good for transfer Mac to PC Preferred format for publication Retains layers .psd (PhotoShop document) Retains layers Can only be opened by Photoshop
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Save as Select TIF from format menu Name the file Select location to “save as” Click save For JPEG Select 7 (medium)
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Photo printing Online printing & sharing Kodak Gallery Snapfish Flickr Print only services Photo kiosks at CVS, Walgreens, Kroger, Biggs
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Image catalog/databases Organization Subcollections Metadata File naming Database software Storage (with backup!) Long-term expandability
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Catalog & storage Software (image preview, search functions) Picasa iPhoto ACDSee Photo Manager Extensis Portfolio Storage (with backup!) CD or DVD Hard drive External hard drive Online
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