Lecture 1
 Univ of Oregon, Dept of Architecture, Intro to Architectural Computer Graphics
  Nancy Cheng, 204c Pacific Hall, 346-3674 nywc@darkwing.uoregon.edu
Session Objectives
  • to understand course goals, content & structure
  • to understand design potential of Photoshop
  • to become acquainted with manipulating & uploading images
Course Overview
  
  • Format & Schedule
  • Staff
  • Rules, behavioral expectation
  • Syllabus: units
  • Resources
  • Software selections, Hardware logistics
 Image Processing: Pixels vs. Vectors Picture Elements (rasters) vs. Segments defined by endpoints

File sizes larger for pixels rather than vectors

Resolution: density of graphic information

  • Image file: Pixels per inch (ppi)
  • Screen resolution: 72 pixels per inch Mac, 75 pixels per inch Windows
  • Printer resolution: Dots of toner per inch (dpi)
  • Screen ruling: Lines per inch (lpi)
  • i.e. A 300 dpi laserprinter uses a 53 to 63 lpi screen ruling. Use100 ppi for 100% enlargement

Resizing images: by resampling a new grid of pixels (file size changes) OR by changing resolution (file size stays the same)

Color Depth: Bits of color information stored per pixel (b/w, grayscale, indexed color, full-color RGB)

Dithering: Approximating more colors with fewer

Anti-aliasing: Simulating smooth diagonal edges with intermediate values
Common Themes Select & Transform

Transformations

  • PhotoCorrection: Contrast/Brightness, Levels
  • Geometric / Physical: Crop, Cut/Paste, Paste Into, Rotate, Skew

Organizing Information for reuse

  • Layers
  • Groups

 Image Processing: Color Models Perceived color = light color as reflected by surface pigment color

Subtractive pigment model:

  • Color Model: CMYK

Additive light models:

  • RGB Red Green Blue
  • HLS Hue Lightness & Saturation
  • HTML hexidecimal (base 16) Web Safe Colors

Photoshop Skills Basic steps

1. Photo-correction: Cropping, retouching w/ Levels, Rotating whole, changing Canvas vs. Image size, Save for Web

2. Selection tools, using the Shift key to add to a selection set, Alt key
to subtract
3. Pixel transformations like Filters, Geometric transformation such as perspective.

Next steps

  • Layers, Vector objects, layer masks, paths, etc.