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Image Editing

Digital images are made up of millions of little dots or "pixels" and the image file specifies the lightness and color of each pixel. The Kodak DC 4800 that you will be using generates images up to 2160 x 1440 pixels. An image this size could take 3 minutes to download over a modem. The old DC 120 that will also be available produces 1280 x 960 pixel images, with a download time of about a minute.

Older computers could be set up with a full screen size of 640 x 480 pixels and 1024 x 768 is a typical resolution for more modern machines. For viewing on a computer there is no sense in having images larger than the resolution of the monitor and we do not often want the image to fill the whole screen. So 640 x 480 pixels is about as large as we need. Images on web pages are typically 320 x 240 pixels. The download time for this size of image might be only 5 seconds, but if there are 5 images on a page it still might take 30 seconds on a modem and people quickly get bored of waiting! Reducing image sizes (and saving in jpeg format) makes Powerpoint files much more manageable too.

You can use the images (accessed through the background link on our home page, http://hcs.osu.edu/ukstudy2002) to practice using Adobe Photoshop. Click on the small image to get a 1280 x 960 image. Use "File" on a MAC or right click over the image on a PC, and then "Save As" to download images and save them to the desktop or disk. (You will need to use the back button on your browser to return from the images to the thumbnail page). Each of the images has something that needs correction. Open the images in Photoshop and try out the following operations (the instructions are primarily for Photoshop Elements, but the equivalent commands for full versions of Photoshop are given in brackets. You can do most or all of this in other software, such as Fireworks or even Photodeluxe):

1. Crop Tool to eliminate unwanted areas
2. Image, Rotate 90° left (CCW) or 90° right (CW)
   
3. Image, Rotate, Canvas Custom (Arbitrary), x° left or right (CCW or CW)
   You will need to crop the image after this adjustment.
   
4. Image Size: adjust to fit within frame 640 pixels wide and 480 pixels high
   
5. Enhance (Image, Adjust), Autolevels: see if this improves appearance (Edit undo if not)
   
6. Enhance (Image, Adjust), Autocontrast: see if this improves appearance (Edit undo if not)
   
7. Enhance (Image, Adjust), Brightness/Contrast if you still think the image needs improvement
   
8. Text tool from the toolbar to label things (adjust font size and color for visibility)

After editing, you would want to save the image and usually you would change the file name from the number given by the camera to something you can understand. Digital cameras usually generate images in jpeg format and can be set to give higher or lower quality images. Higher quality means that less compression is used and the files will be larger than at lower quality. As you save you have the option of adjusting quality on a scale from 1 to 10, but there is no sense in raising quality above that of the original image. Usually 5 to 7 is good enough quality for online material.