Review Questions About Resolution, Quality & Safe Zone | ARTS-4334: Advanced Graphic Design

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Resolution

In the context of printing and other media with fixed linear dimensions, resolution refers to linear pixel density: the number of pixels or dots in a certain span, expressed in such terms as ppi (pixels per inch) and dpi (dots per inch).

In video, film, and computer graphics contexts, the linear measurements of the images are variable, so it doesn’t make sense to refer to the number of pixels per inch or any other linear measure. Consider, for example, that the same 640×480 movie can be shown on the tiny screen of a mobile device, the monitor of a desktop computer, and a huge motion billboard. The number of pixels per inch is different for each of these presentation devices, even though the number of pixels may be the same.

In this context, the term resolution refers to a relative quantity: a ratio of the number of pixels that are rendered to the number of pixels in a source image. For each view, there are two such ratios—one for the horizontal dimension and one for the vertical dimension.

Each composition has its own Resolution setting, which affects the image quality of the composition when it’s rendered for previews and final output. Rendering time and memory for each frame are roughly proportional to the number of pixels being rendered.

When you render a composition for final output, you can use the current Resolution settings for the composition or set a resolution value in the Render Settings dialog box that overrides the composition settings. (See Render settings.)

You can choose from the following Resolution settings in the Composition Settings (Composition > Composition Settings) dialog box or from the Resolution/Down Sample Factor menu at the bottom of the Composition panel:

Auto: (available only for previews) Adapts the resolution of the view in the Composition panel to render only the pixels necessary to preview the composition at the current zoom level. For example, if the view is zoomed out to 25%, then the resolution automatically adapts to a value of 1/4—shown as (Quarter)—as if you had manually chosen Quarter. If a panel contains multiple views, the resolution adapts to the view with the highest zoom level. This setting gives the best image quality while also avoiding rendering pixels unnecessary for the current zoom level.
Note: The Auto setting is ignored for compositions for which the Advanced composition setting Preserve Resolution When Nested is selected.

Full: Renders each pixel in a composition. This setting gives the best image quality, but takes the longest to render.
Half: Renders one-quarter of the pixels contained in the full-resolution image—half the columns and half the rows.
Third: Renders one-ninth of the pixels contained in the full-resolution image.
Quarter: Renders one-sixteenth of the pixels contained in the full-resolution image.
Custom: Renders the image at the horizontal and vertical resolutions that you specify.


720p is a progressive HDTV signal format with 720 horizontal lines and an aspect ratio (AR) of 16:9 (1.78:1). All major HDTV broadcasting standards (such as SMPTE 292M) include a 720p format which has a resolution of 1280×720; however, there are other formats, including HDV Playback and AVCHD for camcorders, which use 720p images with the standard HDTV resolution.

The number 720 stands for the 720 horizontal scan lines of image display resolution (also known as 720 pixels of vertical resolution), while the letter p stands for progressive scan (i.e. non-interlaced). When broadcast at 60[note 1] frames per second, 720p features the highest temporal (motion) resolution possible under the ATSC and DVB standards. The term assumes a widescreen aspect ratio of 16:9, thus implying a resolution of 1280 px × 720 px (0.9 megapixels).

720i (720 lines interlaced) is an erroneous term found in numerous sources and publications. Typically, it is a typographical error in which the author is referring to the 720p HDTV format. However, in some cases it is incorrectly presented as an actual alternative format to 720p. In fact, no proposed or existing broadcast standard permits 720 interlaced lines in a video frame at any frame rate.

1080p (also known as Full HD or FHD) is a set of HDTV high-definition video modes characterized by 1080 horizontal lines of vertical resolution[1] and progressive scan, as opposed to interlaced, as is the case with the 1080i display standard. The term usually assumes a widescreen aspect ratio of 16:9, implying a resolution of 1920×1080 (2.1 megapixel) often marketed as Full HD.


Quality

Different from both Magnification and Resolution is Quality. Whereas the first two are parameters that affect an entire composition. Quality is set on a layer-by-layer basis in the Timeline panel. Along the top of the Switches/Modes column, Quality is the switch with the backward-leaning slash. The Quality choices in After Effects CS6 are Best, Draft, and Wireframe. The Quality choices in After Effects CC 2014 are Bicubic, Bilinear, and Draft.

The default for the new layers is to use Best Quality (a forward-leaning slash) in After Effects CS6. Click on the Quality switch to toggle between Draft (broken line) and Best (solid line). When rending a movie, the render settings can override these settings and force all layers to render in Best Quality, but the Draft mode can speed up your workflow when you are working.

Set scaling quality using Bicubic Sampling
After Effects CC offers you another way to scale things that’s called Bicubic. Bicubic interpolation feature uses at least four times as many pixels as are used in traditional Bilinear sampling, so the quality tends to be better. It’s particularly better when you working with image and video but it’s not necessary better when you working with graphics.
http://tv.adobe.com/watch/learn-after-effects-cc/bicubic-scaling/


Safe zones, grids, guides, and rulers

In the Footage, Layer, and Composition panels, you can display safe zone margins, grids, rulers, and guide lines to align and arrange visual elements.

  • To change settings for safe-zone margins, grids, and guides, choose Edit > Preferences > Grids & Guides (Windows) or After Effects > Preferences > Grids & Guides (Mac OS).
  • To show or hide safe zones, grids, guides, or rulers, click the Grid And Guides Options button and choose the appropriate item, or use a menu command or keyboard shortcut in the View menu.
  • To toggle between showing and hiding the safe zones, Alt-click (Windows) or Option-click (Mac OS) the Grid And Guide Options button.
  • To make layer edges and mask edges snap to grids or guides, choose View > Snap To Grid or View > Snap To Guides.
  • To create a guide line, drag from either ruler.
  • To delete a guide line, drag it to a ruler using the Selection tool.
  • To delete all guide lines, choose View > Clear Guides.
  • To move a guide line, drag it using the Selection tool.
  • To lock or unlock guides, choose View > Lock Guides. Locking a guide prevents it from being accidentally moved.
  • To set the zero point (origin) for the rulers, drag the crosshair from the intersection of the two rulers (in the upper-left corner) into the image area. Reset the z

Source: Adobe.com

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