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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 can use generates images up to 2160 x 1440 pixels. With moderate compression each image ends up about 0.5 MB. Older cameras produce 1280 x 960 pixel images that are about 0.2 MB.

For viewing on a computer there is no sense in having images at higher resolution than the monitor and 800 x 600 pixels is about as large as we need. Reducing image sizes (and saving in jpeg format) makes Powerpoint files manageable in FTP and will save space on your Tripod account.

You can use some images from our recent Field Trip to practice using Adobe Photoshop. Click on the small image to get a 2160 x 1440 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. 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 Size: adjust to fit within frame 800 pixels wide and 600 pixels high
   
4. Enhance (Image, Adjust), Autolevels: see if this improves appearance (Edit undo if not)
   
5. Enhance (Image, Adjust), Autocontrast: see if this improves appearance (Edit undo if not)
   
6. Enhance (Image, Adjust), Brightness/Contrast if you still think the image needs improvement
   
7. 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 you should keep this format for your presentation. As you save you have the option of adjusting quality on a scale from 1 to 10 which also affects file size. There is no sense in raising quality above that of the original image and 5 to 7 is good enough quality for online material. Transfer the edited images to your Tripod account.