Week 1: Introduction to Digital Imaging

Overview of Rotoscoping



Basic Rotopaint Terms

  • frame
  • roto
  • layer
  • opacity
  • render
  • preview
  • layer group
  • raw footage
  • timeline



    Roto refers to the 2D technique of manually (or semi-procedurally) tracing (rotoscope, rotospline) or painting (rotopaint) over a sequence of moving images. Roto allows for the repurposing of the motion of a reference sequence, for example, the choreography of Snow White and her physical reactions to characters in the film was performed by a stage actor. Roto also allows for the removal of imagery within the frame, for example, wire removal in The Matrix.



    History and Examples

    Brief History of Rotoscoping




    For this exercise you should be familiar with the following tools:

    It’s useful to know the following shortcuts and keystroke combo’s while using these tools.

      While using the Brush Tool, holding down Option/Alt will call up the Eye Dropper
      While using the Paint Bucket Tool, holding down Option/Alt will call up the Eye Dropper
      While using any tool, holding down the Spacebar will call up the Hand Tool
      Command/Control+D to deselect all
      Command/Conttrol +/- to Zoom In/Out



    RotoPaint Exercise

    Use either of the following sequential image sets for the RotoPaint exercise



    Tutorial File:

    RotoPaint Exercise




    Save for Web Settings for Animated GIF (Ps CC [2015])

  • File > Export > Save for Web (Legacy)




    • Preset (top right)

      1. select from a list of presets, ranging from a higher quality/larger file size (GIF 128 Dithered) to a lower quality/smaller file size (GIF 64 No Dither), as well as other image formats


    • File Format Menu (below presets)

      1. Set this to GIF


    • Color Reduction Method and Colors (Below File Format Menu)

      1. Specifies a method for generating the color lookup table and the number of colors you want in the color lookup table. You can select one of the following color reduction methods:

        1. Perceptual

          Creates a custom color table by giving priority to colors for which the human eye has greater sensitivity.

        2. Selective

          Creates a color table similar to the Perceptual color table, but favoring broad areas of color and the preservation of web colors. This color table usually produces images with the greatest color integrity. Selective is the default option.

        3. Adaptive

          Creates a custom color table by sampling colors from the predominant spectrum in the image. For example, an image with only the colors green and blue produces a color table made primarily of greens and blues. Most images concentrate colors in particular areas of the spectrum.

        4. Restrictive (Web)

          Uses the standard 216‑color color table common to the Windows and Mac OS 8‑bit (256‑color) palettes. This option ensures that no browser dither is applied to colors when the image is displayed using 8‑bit color. (This palette is also called the web‑safe palette.) Using the web palette can create larger files, and is recommended only when avoiding browser dither is a high priority.

        5. Custom

          Uses a color palette that is created or modified by the user. If you open an existing GIF or PNG‑8 file, it will have a custom color palette

        6. Black and White, Grayscale, Mac OS, Windows

          Use a set palette of colors


    • Dithering Method, and Dither

      1. Determines the method and amount of application dithering. Dithering refers to the method of simulating colors not available in the color display system of your computer. A higher dithering percentage creates the appearance of more colors and more detail in an image, but can also increase the file size. For optimal compression, use the lowest percentage of dither that provides the color detail you require. Images with primarily solid colors may work well with no dither. Images with continuous-tone color (especially color gradients) may require dithering to prevent color banding.
        1. Diffusion

          Applies a random pattern that is usually less noticeable than Pattern dither. The dither effects are diffused across adjacent pixels.

        2. Pattern

          Applies a halftone-like square pattern to simulate any colors not in the color table.

        3. Noise

          Applies a random pattern similar to the Diffusion dither method, but without diffusing the pattern across adjacent pixels. No seams appear with the Noise dither method.


    • Transparency and Matte

      • Determines how transparent pixels in the image are optimized
        1. Transparency Dithering

          1. When the Transparency option is selected, you can choose a method for dithering partially transparent pixels


    • Interlace

      1. Displays a low-resolution version of the image in a browser while the full image file is downloading. Interlacing can make downloading time seem shorter and can assure viewers that downloading is in progress. However, interlacing also increases file size.


    • Web Snap

      1. Specifies a tolerance level for shifting colors to the closest web palette equivalents (and prevent the colors from dithering in a browser). A higher value shifts more colors.


    • Lossy

      1. Reduces file size by selectively discarding data. A higher Lossy setting results in more data being discarded. You can often apply a Lossy value of 5–10, and sometimes up to 50, without degrading the image. The Lossy option can reduce file size by 5% to 40%.
      2. You cannot use the Lossy option with the Interlaced option or with Noise or Pattern Dither algorithms.


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