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02/03/09© Vic Dohar, 20091 Introduction to Digital Images Presented and Written by Vic Dohar
02/03/09© Vic Dohar, 20092 Purpose To provide you with the basic concepts and understanding of digital images Explain why knowing about digital images is important in today’s technical environment Demonstrate some basic editing tasks that even you can perform on software that is free
02/03/09© Vic Dohar, 20093 Why Do I Need To Know About Digital Images? It is important to have a basic understanding of digital images for: –Advertising images of your artwork by uploading them to the internet/web page –Participating in juried exhibitions that only except digital submissions –Editing your digital images (crop, rotate, resize) –Managing an inventory of your images as a reference for subject matter
02/03/09© Vic Dohar, 20094 Juried Digital Submissions Jury only accepts digital images: “The image submitted should not exceed 72 dpi and the image should fit proportionally within 6″x6″ dimension thus if the image is not a square do not stretch the image to make it fit as a square. However, the image should fill most of the area within 6″x6″ appropriately.” (source RBC Canadian Painting Competition) You will have to know how to create a digital image that is 6″ x 6″ at 72 DPI.
02/03/09© Vic Dohar, 20095 Juried Digital Submissions Jury accepts digital images following strict rules and guidelines –File format –File size (dimension) –File name –Image requirements (source TWSA Prospectus and Entry Instructions 2009)
02/03/09© Vic Dohar, 20096 Uploading to Web Page Limits or restrictions for posting images on web galleries (source www.canartscene.com)
02/03/09© Vic Dohar, 20097 Image Quality in Digital Images Understanding quality plays an important role in manipulating digital images for different requirements –You want to make prints or Giclees (very high quality) –You want to create cards or book marks to sell at exhibitions (high quality) –You want to email your latest set of paintings to prospective buyers or galleries (medium quality) –You want to personalize your business card by incorporating the design from one of your paintings (low to medium quality) –Upload images to the web (low quality)
02/03/09© Vic Dohar, 20098 Now It’s Time to Get Technical Brace yourselves … relax … get comfortable Pretend you’re back in school Try and think like a computer geek You may even learn something new tonight Please ask questions at anytime Are you ready?
02/03/09© Vic Dohar, 20099 What is a Digital Image? Representation of a picture or photograph (analog) by digital means obtained either from a digital camera or scanner A digital image is comprised of columns and rows each containing any number of pixels defining its dimension Each pixel has a colour A digital image is stored as a file in various formats (e.g. JPG, TIFF, GIF, BMP, raw, etc…) Image dimension and compression are important properties that define the size and quality of a digital image
02/03/09© Vic Dohar, 200910 Let’s Begin With The Pixel A coloured square that is the smallest part of a digital image Sometimes referred to as a dot or a cell one pixel
02/03/09© Vic Dohar, 200911 The Mega Pixel A mega pixel simply means 1,000,000 pixels (something times a million) Mainly associated with digital cameras defining the maximum number of pixels in a digital image MS Explorer provides info when a file is selected Dimensions: 2048 x 1536 Date Picture Taken: 09/05/2005 9:19 AM Camera Model: Canon PowerShot A70 Type: JPEG Image Size 2.12 MB Taken from a 3.2 MP digital camera, because image contains 3,145,728 pixels (2048 x 1536)
02/03/09© Vic Dohar, 200912 The Mega Pixel Myth “My 8MP camera is twice as good as a my old 4MP camera.” TRUE / FALSE? 2000 pixels Total number of pixels = 4,000,000 (4MP) 4000 pixels Total number of pixels = 16,000,000 (16MP)
02/03/09© Vic Dohar, 200913 The Mega Pixel Myth To obtain an image with a quality twice as better, the mega pixel count has to be 4x greater (e.g. 16MP compare to a 4MP) Therefore there is not a significant difference in image quality between a 8MP and 10MP camera What does this mean? It means you can save some $$$ when shopping around for a digital camera.
02/03/09© Vic Dohar, 200914 The Mega Pixel Myth For example, these two Nikon cameras have the same internal workings, but one has a higher MP and a slightly better lens Keep the money in your pocket for cameras with similar features but offer different MP ratings
02/03/09© Vic Dohar, 200915 OK – Now What? You now know what comprises a digital image. We will now go through the steps in how to obtain, edit and save a digital image and prepare it for a web gallery and/or juried submission
02/03/09© Vic Dohar, 200916 Digital Imaging Steps 1.Obtaining digital images of your artwork 2.Performing edits on the digital image 3.Saving the digital image 4.Preparing digital image for various needs
02/03/09© Vic Dohar, 200917 Obtaining Digital Images of Your Artwork Sources: –Ask for a Photo CD when developing film –Scan existing pictures/slides of artwork –Scan artwork directly –Take a picture with a digital camera Ask a friend that has all these toys to help!
02/03/09© Vic Dohar, 200918 Using a Digital Camera Read the camera’s manual to ensure picture is taken with the highest quality (image compression) and highest resolution (maximum image dimension) Use tripod along with timer setting If digital camera has manual settings, bracket several shots with varying exposures Use adequate lighting and if possible adjust camera setting to correct white balance Do not use a flash Make sure artwork is not behind glass
02/03/09© Vic Dohar, 200919 Issues with Images from Digital Cameras Uneven/poor light distribution (brightness) Keystone/distortion around perimeter White balancing is off (warm or cool) Usually require to crop image Majority of these issues can be corrected when editing the digital image
02/03/09© Vic Dohar, 200920 Using a Scanner Recommend using a see-through scanner allowing to place scanner on artwork rather than placing artwork upside-down on a flat-bed scanner Can scan at various resolutions, but recommend 300 DPI providing a good quality
02/03/09© Vic Dohar, 200921 Issues with Images from Scanners May contain noise due to surface textures, however it provides even light distribution Images from scanners usually require more disk space Multiple scans from a large format painting will have to be digitally stitched together (Hint! Use camera’s panoramic software) If image has to be rotated do so during the scanning process Require to crop image, but the image dimension and resolution will be accurate
02/03/09© Vic Dohar, 200922 Demonstration #1 Digitally stitch together images scanned in multiple sections using software that came with digital camera Use Google’s Picasa 3 to compare images taken with a digital camera with one that is scanned
02/03/09© Vic Dohar, 200923 Digital Imaging Steps 1.Obtaining digital images of your artwork 2.Performing edits on the digital image 3.Saving the digital image 4.Preparing digital image for various needs
02/03/09© Vic Dohar, 200924 Digital Image Editing Software Numerous software applications available for editing digital images –Free/shareware applications from internet (Google’s Picasa 3, PhotoFiltre, GIMP, …) –Purchase (Adobe Photoshop, Corel Paint, Paint Shop Pro, …) Also look at the abilities of software that comes with camera and scanner
02/03/09© Vic Dohar, 200925 Software Musts Ability to rotate and crop image Ability to resize/re-sample image, change or scale dimension and/or resolution (each have their own terminology, practice to get familiar) Ability to adjust image –Remove noise (smooth image) from a scanned image –Lighten/darken image (auto-adjust image) –Correct colour –Adjust white balance Almost all software now-a-days has these features
02/03/09© Vic Dohar, 200926 Basic Editing Steps i.Rotate image to correct orientation (if required) ii.Crop image (if required) iii.Adjust/edit image (if required) iv.Save image with a meaningful name If you perform these basic steps, you will have a master image from which to apply adjustments and create other images at different sizes or resolutions.
02/03/09© Vic Dohar, 200927 Demonstration #2 Using Google’s Picasa 3 to perform the following on a digital image taken from a camera –Rotate/straighten image so it is square –Crop image –Adjust image (brighten, darken)
02/03/09© Vic Dohar, 200928 Editing With Picasa From the library of thumbnail pictures, double-click on an image to edit Basic edits are available from the Basic Fixes menu Remember to save edits between a crop and/or rotation Save edits by returning to the library of thumbnail images and pressing the Save to Disk button When saving edits, a backup of the image is saved in the Originals folder allowing you to undo edits
02/03/09© Vic Dohar, 200929 Digital Imaging Steps 1.Obtaining digital images of your artwork 2.Performing edits on the digital image 3.Saving the digital image 4.Preparing digital image for various needs
02/03/09© Vic Dohar, 200930 Saving Digital Images Each digital image is stored as a separate file The most common file format from digital cameras is JPEG or JPG (Joint Photographic Experts Group) Professional cameras also store in RAW or their native format Assign meaningful names to files Always have a “master” file from which variations can be created When saving JPG files on some applications, you have to specify the degree of image compression
02/03/09© Vic Dohar, 200931 Image Compression Compression reduces the file size on disk by joining pixels with similar value/colour All JPG files have a certain degree of compression; once compressed you can not revert back to its original state (this is known as lossy compression ) … unless you save a copy of the original image! Follow this general rule comparing compression, quality and file size on disk –High compression = lower quality = smaller file size –Low compression = higher quality = larger file size
02/03/09© Vic Dohar, 200932 Comparing Degrees of Compression Low compression High quality 250 KB High compression OK quality 71 KB Extreme compression Poor quality 7 KB
02/03/09© Vic Dohar, 200933 Why is Compression Important? When submitting digital images to a jury, want high quality so as not to loose any detail High quality images are not required when displaying images on the internet/web pages –Saves on disk space –Displays/downloads/uploads faster –Public does not have access to your high-quality images Resolution for images on the web can be 96 DPI
02/03/09© Vic Dohar, 200934 Demonstration #3 Using Google’s Picasa 3 to perform export an image at a higher compression/lower quality –Export image to another folder –Specify image dimension and quality
02/03/09© Vic Dohar, 200935 Exporting Image From Google From library of thumbnails, select images and select Export Picture to Folder from the File drop down menu Specify location and name of folder Select image size (longest dimension) Select quality (preset or custom)
02/03/09© Vic Dohar, 200936 Quick Review This is what you have learned so far: –Digital images can be used for various purposes –Know what is a pixel and mega pixel –Mega pixel ratings is really not that important comparison between digital camera models –Obtain digital images from cameras or scanners –Basic editing steps –Why compression of digital images is important
02/03/09© Vic Dohar, 200937 Digital Imaging Steps 1.Obtaining digital images of your artwork 2.Performing edits on the digital image 3.Saving the digital image 4.Preparing digital image for various needs
02/03/09© Vic Dohar, 200938 Preparing a Digital Entry for a Jury Ensure you know what is required for digital entry –High quality image –Pixel dimensions Calculate image dimensions based on size requirements –4”x 6” image at 300 DPI
02/03/09© Vic Dohar, 200939 Image Size Image size is referred to the size of the image when it is displayed (usually in inches) The size can be any since the image can easily be enlarged or reduced (zooming) Base your calculations on the image dimension or number of pixels –4”x 6” image size at 300 DPI (resolution) –In pixels this is 1200 x 1800 pixels Resolution is the number of pixels per unit of measurement (e.g. one inch)
02/03/09© Vic Dohar, 200940 The Image Formula All three properties are related as follows: Dimension (pixels) = Resolution (DPI) x Size (inches) Size (inches) = Dimension (pixels) ÷ Resolution (DPI) Resolution (DPI) = Dimension (pixels) ÷ Size (inches) DIMENSION (pixels) RESOLUTION (DPI) SIZE (inches) ÷ ÷ x 1200 x 1800 pixels 300 DPI 4 x 6 inches
02/03/09© Vic Dohar, 200941 One Word of Caution When submitting digital images to a jury, avoid “over”- editing the digital image using tools like smoothing, burring, sharpening, removing blotches or errors, etc… Adjustments that do not accurately portray the original piece of artwork may disqualify entry in a juried show
02/03/09© Vic Dohar, 200942 Demonstration #4 Using the export function from Google’s Picasa 3 to prepare an image for the TWSA submission
02/03/09© Vic Dohar, 200943 Image for TWSA Submission –File format must be JPG, highest quality, no compression (error) –Entry image should be no smaller than 900 pixels in the longest dimension –Also prepare entry for catalogue, high-resolution 4”x 6” at 300 DPI –Name file accordingly
02/03/09© Vic Dohar, 200944 Review & Tips Read camera manual to determine the maximum pixel dimension of an image and set camera accordingly Be aware of compression/quality settings on camera High quality = low compression = large file size Low quality = high compression = small file size Familiarize yourself with software’s resizing/re- sampling methods of digital images Have at least one master image at the highest resolution possible from which other images at lower resolution or different dimensions can be created
02/03/09© Vic Dohar, 200945 Review & Tips Give meaningful names to your digital files: RideauCanal_Scan300DPI.jpg RideauCanal_Master.jpg RideauCanal_Camera.jpg RideauCanal_Thumbnail.jpg RideauCanal_400x250.jpg RideauCanal_MAA_Web_Gallery.jpg Consider investing in software to manage and organize your digital images (Google’s Picasa) Practice, practice, practice and have fun! Contact me for help: email@example.com
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