I messed up some dates an percentages in the overview and assignments pages

Dorkbot SF

Leonardo, the International Society for the Arts, Sciences and Technology

Leonardo LASER (Leonardo Art Science Evening Rendezvous)

Site resources listing...

An interesting web site on what can go wrong with Photoshop retouching

Never believe anything you see in a photograph!

And there's nothing particularly new about it, either

Paul Brown

• Studied at Liverpool Polytechnic and Slade School of Art, London, in the 70's
• Pioneer in algorithmic "Game of Life," or cellular automota generated artworks
• A nice piece in Processing

James Faure-Walker

• Studied at the Royal College of Art in the early 70's
• Creates works which are very traditional, but use a computer as a jumping off point with digital prints

Two Color Worlds

• RGB for screen
• CYMK for paper
• C = Cyan
• Y = Yellow
• M = Magenta
• K = blacK

Properties of Color

• 
  Hue: the "color"of the color, or the wavelength of light
• 
  
  
  Saturation: the intensity of the color
• 
  
  
  Brightness/Value: the relative lightness or darkness of the color

Gamut: The set of possible colors within a given domain

The idea being that any display medium, like a monitor or printed paper can only show a limited range of colors.

Computer monitors can show more colors than paper printed with Cyan Magenta Yellow and Black (CMYK) inks.

Paper printed with CMYK can show fewer colors than the same paper printed with CMYK and Pantone custom ink colors

Good references:
• techmind.org
• Munsell Color Science Lab

sRGB = "standard" RGB

Demo Photoshop's color tools

• 
  Color Picker
• 
  Color Palette
• 
  Swatches Palette
• 
  Swatches Menu
• 
  Info Palette

See Chapter 7 in Photoshop CS3 Studio Techniques

Demo Photoshop color correction through the Curves Dialog…

Images I'll be using
• katz_gray
• skintone_ref
• skintone_before

Using gray to fix color

• Gray is made up of equal parts of Red Blue and Green
• 
• Check out the info palette to see if something really is gray or not
• The panel in the image above should be gray, not greenish gray (notice the high G and low R values)
• Possible reasons for off-color-ness (aka color cast)
  • Wrong film for the light
  • Old bulbs in the film scanner
  • Wrong temperature for the color developing chemicals
  • Bad settings in the operating system color calibration

Ways to do color correction:

• 
• Use the Menu > Image > Adjustments > Color Balance… dialog with the info window (in our example, more red, less green)
• 
• Use the Menu > Image > Adjustments > Curves…
  • Find a gray spot, mark it with some guides
  • Calculate the average of the three color channel values, like (112+169+161)/3 or 147
  • 
  • In each of the color channels, put a point on the line with command-click and and set the Output of that point to the average (147)
  • In this case, we'll tweak the saturation a little bit too.
  • 

Matching Skin Tones

You can match skin tones between pictures, which can be really handy. Use available stock photography from places like istockphoto.com to get skin tones you might want to match.

• First, start with a reference photo
• 
• Using the eyedropper and the info panel, write down the RGB values at a particular location that's in a middle range. Also, write down the Brightness (B) of the HSB values
• 
• In this case: R=226, G=162, B=120 and Brightness = 89% (you can find set the Info window to show HSB with the little popup menu in the upper right of the panel)
• Take the image you want to change to match the reference image's skin tone:
• 
• ...And find a spot with the same Brightness (89%)
• 
• Using the same technique with curves, modify the curves for that point to the RGB values from the reference image
• 
• The result:
• Before
  After

Photoshop's forté

What those bits of color depth are used for in 32bit color

What Is A Selection?

• A type of “masking”
• When you select something, you can differentiate it from the rest of the image and either effect it or everything but it
• Let's demo the tools
• Marquee
• Lasso
• Quick Selection
• Magic Wand
• Quick Mask
• Paths

• Pick a theme that includes a short piece of text with a title
• Try poetry
• Keep the text to no more than a page
• Due next class