Difference between revisions of "Picturing Plants - Photoshop"

Revision as of 13:32, 23 May 2013

Project overview

• Preparing digital images for print. Photo Quality prints need thousands of linear pixels. This means between 180 and 360 pixels per inch (ppi.) So, if a print is 10” long, you need 1800 – 3600 linear pixels for it to look good. (10” x 360=3600pixels).
• Prepare images for the web. By contrast, images for the web or email need to be sized for screen resolution. Depending on the monitor you’ll need 800-1920 pixels to fill the screen.

Best practices

• Start Big: larger image files (both in file size and in overal number of pixels) provide you with higher quality images. You can always scale the image down but you can't scale it up.
• Keep your original: These images are typically your highest quality image and you may need to go back to them from time to time.
• File naming is important: Come up with a naming convention that helps you quickly identify the image without having to open it up. Names should include descriptive info, version, size or intended use.
  • Example: Rainier_sunrise_1200_BW.psd - this file name tells me about the subject of the photo, the image size typically its width and any processing I've done, this one is a black and white version, it's file format is Photoshop.

Scanning

Using the Epson scanners in the Computer Center. See: Scanning - Mac

1. Scan one drawing from a station connected to a scanner
2. Save as TIFF to your cubby on Orca. See: Connecting to Orca programs at File Space Overview
3. Go back to your station and copy your scanned image to your local hard drive and open locally in Photoshop

Intro to Photoshop

Photoshop interface and navigating an image

1. File > Open your scanned document in Photoshop
2. Keyboard shortcuts for navigating your image
   • Zoom in/out: Cmd +/-
   • Hand tool: Space Bar
3. Image > image Size to see the overall size and resolution of your image
   • for print, image resolution should be at least 300 dpi
4. File > Save as choose Photoshop as the file format. Note the .psd extension.

Editing your image

• If needed, rotate your image Image > Image Rotation
• Crop and set the horizontal/vertical alignment for your image using the crop/align tool
  • Note what happens if you choose Not to "delete cropped pixels"
  • this relates directly to you Canvas size found in Image > Canvas Size

Image Adjustments

1. Image mode
   • All images must be in RGB mode to print properly in the DIS. Go Image > Image mode and set the mode to RGB if it is not already
2. Adjust the image density (overall brightness/darkness of an image)
   • Image > Adjustments > Brightness and Contrast is the most basic way to do this
   • Image > Adjustments > Levels give you even more control and can work to clean-up scanned drawings or bring added depth the dull snapshots
   • Recommended: try using Levels as an Adjustment Layer - Layer > New Adjustment layers > Levels

Image Touch up

1. Working with Layers
   • Creating A New Layer
   • Moving/reordering layers
2. Selections can be made to fine-tune certain areas of your image. There are several tools that can be used to make a selection, all found on the tool bar.
   • Try the Quick Selection Tool first.
3. Techniques for correction
   • Healing Brush Tool - easily paint over bad parts of your images with the parts you want
   • Blur Tool - add a little extra blurriness to sections of your image
   • Dodge and Burn tools to make areas of your image lighter or darker
4. Refine edges - if you are extracting an image from its background to place on a new background you may notice a "halo" around the cut-out image. This halo is called edge aliasing and can be eliminated by using the "Refine Edge" tool. See the refine edge tutorial for tips on using it effectively.

Saving your work

1. File > Save as choose Photoshop as the file format. Note the .psd extension.

Additional Resources

• Lynda.com Video Tutorials
• Digital Image Basics from UT Austin