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Get the Best Digital Images Possible
What’s it all about anyway?What’s it all about anyway?
Issues to Consider
nn ResolutionResolution
nn Image SizeImage Size
nn File SizeFile Size
nn Intended Use of the ImageIntended Use of the Image
nn File FormatsFile Formats
Issues to Consider
nn Image size (width and height pixel Image size (width and height pixel dimensions)dimensions)
uuPixel dimensions of original image Pixel dimensions of original image determine how large the finished product determine how large the finished product can be without degrading the image can be without degrading the image qualityquality
nn File SizeFile Size
uuLarger file sizes cause slower page Larger file sizes cause slower page loading for Web pagesloading for Web pages
uuLonger print times for printed imagesLonger print times for printed images
uuThe more pixels in an image The more pixels in an image –– the larger the larger the file sizethe file size
Issues to Consider
nn What’s the intended use of the image?What’s the intended use of the image?uu PrintPrint
tt Print dimensions are more important than Print dimensions are more important than pixel dimensionspixel dimensions
tt Higher resolutions produce better quality Higher resolutions produce better quality printed imageprinted image
uu Online viewingOnline viewingtt File size is the most important considerationFile size is the most important considerationtt Pixel dimensions determine approximate Pixel dimensions determine approximate
viewing sizeviewing size
Issues to Consider
Resolution
nn What IS resolution?What IS resolution?uuAbility to resolve detail (changes in Ability to resolve detail (changes in
contrast between pixels)contrast between pixels)uuMore commonly used to describe total More commonly used to describe total
number of pixels in captured imagenumber of pixels in captured imageuuThe greater the number of pixels The greater the number of pixels
captured, the better the resolution captured, the better the resolution –– but but ––uuMore pixels means larger file sizesMore pixels means larger file sizes
Types of Resolution
nn Image ResolutionImage Resolution
uu # of pixels per unit of length measured in # of pixels per unit of length measured in pixels per inch (pixels per inch (ppippi))
uuA high resolution image contains more A high resolution image contains more pixels than an image of the same pixels than an image of the same dimensions with a low resolutiondimensions with a low resolution
nn Monitor ResolutionMonitor Resolutionuu # of pixels per unit of length on a monitor # of pixels per unit of length on a monitor
measured in pixels per inch (measured in pixels per inch (ppippi))uu Image pixels translate directly into Image pixels translate directly into
monitor pixelsmonitor pixelstt If image resolution is higher than If image resolution is higher than
monitor resolution, image appears monitor resolution, image appears larger on screen than it printslarger on screen than it prints
Types of Resolution
nn Common Monitor ResolutionsCommon Monitor Resolutions
uu 640 X 480640 X 480
uu 800 X 600800 X 600
uu 1024 X 7681024 X 768
uu 1280 X 10241280 X 1024
nn Newer monitors can have even higher Newer monitors can have even higher resolutionsresolutions
Types of Resolution
nn The same image displayed at two different The same image displayed at two different monitor resolutions will appear at different monitor resolutions will appear at different sizessizes
nn The monitor’s physical size also influences The monitor’s physical size also influences the size the image appears atthe size the image appears at
Types of Resolution
nn An image displayed on a 19” monitor set to An image displayed on a 19” monitor set to display 1024 X 768 pixels looks much display 1024 X 768 pixels looks much larger than the same image displayed on the larger than the same image displayed on the same monitor at 1280 X 1024 pixelssame monitor at 1280 X 1024 pixels
Types of Resolution
nn Output or Printer ResolutionOutput or Printer Resolution
uu # of ink dots per inch produced by printer # of ink dots per inch produced by printer measured in dots per inch (dpi)measured in dots per inch (dpi)
uuHigher resolution printers combined with Higher resolution printers combined with higher resolution images generally higher resolution images generally produce the best qualityproduce the best quality
Types of Resolution
Print Resolution
nn Appropriate resolution for printing is Appropriate resolution for printing is determined by both the printer’s resolution determined by both the printer’s resolution and the screen frequency (lines per inch and the screen frequency (lines per inch ––lpilpi) of the halftone screens used by the ) of the halftone screens used by the printer to produce imagesprinter to produce images
nn Computer Graphics Rule of Thumb:Computer Graphics Rule of Thumb:
uuScan image at 1.5 to 2 times the screen Scan image at 1.5 to 2 times the screen frequency used by the printerfrequency used by the printer
ttScreen frequency is usually 133 Screen frequency is usually 133 lpilpi
uu 133 133 lpi lpi x 1.5 = 200 x 1.5 = 200 ppi ppi correct scanning correct scanning resolution to useresolution to use
Getting the Right Print Resolution
Digital Cameras
nn Camera resolution is measured in terms of Camera resolution is measured in terms of the maximum number of pixels the image the maximum number of pixels the image sensor is capable of capturingsensor is capable of capturing
nn Megapixels Megapixels –– 1 1 megapixel megapixel = 1 million = 1 million pixelspixels
nn 3.1 3.1 megapixel megapixel camera produces images with camera produces images with 2048 X 1538 pixel dimensions2048 X 1538 pixel dimensions
nn Assume you need at least a 150 Assume you need at least a 150 ppi ppi image image resolution for good print qualityresolution for good print quality
uuTo get a good 4 X 6 print To get a good 4 X 6 print –– you need to you need to capture at least 600 X 900 pixels (150 X capture at least 600 X 900 pixels (150 X 4, 150 X 6)4, 150 X 6)
uuFor 8 X 10 print For 8 X 10 print –– you need at least 1200 you need at least 1200 X 1500 pixelsX 1500 pixels
Digital Cameras
nn Some cameras have multiple resolution Some cameras have multiple resolution settings (pixel dimensions) availablesettings (pixel dimensions) available
nn Use lower resolutions for smaller file sizes Use lower resolutions for smaller file sizes if you don’t need to enlarge the image for if you don’t need to enlarge the image for printingprinting
Digital Cameras
Image Size
nn Best to create the image at the final size you Best to create the image at the final size you want to usewant to use
uuYou can always resize images smaller You can always resize images smaller without loss of qualitywithout loss of quality
uuResizing the image larger later can Resizing the image larger later can degrade image qualitydegrade image quality
nn Digital CamerasDigital Cameras
uu Start with camera set at highest resolution Start with camera set at highest resolution setting if you’ll need to print a larger imagesetting if you’ll need to print a larger image
tt Use image editing software to resize print Use image editing software to resize print dimensions/increase image resolutiondimensions/increase image resolution
uu If image will be used on Web page, reduce the If image will be used on Web page, reduce the camera resolution setting to reduce the file size camera resolution setting to reduce the file size and image dimensions when viewed on screenand image dimensions when viewed on screen
Image Size
nn ScannersScanners
uu Set scanning resolution as high as necessarySet scanning resolution as high as necessary
tt Scan at higher resolutions for both print and Scan at higher resolutions for both print and online viewing for best qualityonline viewing for best quality
uu Choose the desired print dimensions before Choose the desired print dimensions before scanningscanning
tt Best to scan larger and rescale smaller, than Best to scan larger and rescale smaller, than to scan small and then try and resize largerto scan small and then try and resize larger
Image Size
nn If you’ve scanned at a higher resolution (200If you’ve scanned at a higher resolution (200--300 300 dpi):dpi):uu If image is to be used online, use image editing If image is to be used online, use image editing
software to lower image resolution to 72software to lower image resolution to 72--96 96 ppippitt Image detail captured by higher resolution Image detail captured by higher resolution
scan will still be there, but file size will be scan will still be there, but file size will be smallersmaller
tt Improves quality of images printed from Improves quality of images printed from Web pagesWeb pages
Image Size
File Formats
nn JPEG (.JPEG (.jpgjpg) Joint Photographic Experts Group) Joint Photographic Experts Groupuu Image is automatically compressed so file size Image is automatically compressed so file size
is smaller as camera saves the image as a JPEG is smaller as camera saves the image as a JPEG filefile
uu Most digital cameras use the Most digital cameras use the jpg jpg format by format by defaultdefault
uu Some cameras use a proprietary file format Some cameras use a proprietary file format you’ll need to convert to useable formats using you’ll need to convert to useable formats using image editing softwareimage editing software
uuWhen editing JPEG images, save in When editing JPEG images, save in another format while editing another format while editing –– each time each time you resave a JPEG image you lose more you resave a JPEG image you lose more data, lowers image qualitydata, lowers image quality
File Formats
nn Many digital cameras have different quality Many digital cameras have different quality settingssettingsuu Hi Hi –– usually uncompressed TIFF filesusually uncompressed TIFF filesuu Fine Fine –– lowest compression JPEG file, larger file lowest compression JPEG file, larger file
sizesizeuu Normal Normal –– more compression, smaller file sizemore compression, smaller file sizeuu Basic Basic –– most compression, smallest file sizemost compression, smallest file size
nn Each setting compresses the image with more or Each setting compresses the image with more or less loss of data less loss of data –– affects file size and image affects file size and image quality, not image resolutionquality, not image resolution
File Formats
nn Most scanners allow a choice of different Most scanners allow a choice of different file formats to save the final scanned imagefile formats to save the final scanned image
nn Choose the format that’s best for the Choose the format that’s best for the intended use of the imageintended use of the image
nn JPEG is best for online images due to image JPEG is best for online images due to image compression compression –– smaller file smaller file sizssizs
nn TIFF is often best for printing images TIFF is often best for printing images –– no no image compression, no loss of dataimage compression, no loss of data
File Formats
