RGB Spectrum SuperView 3000 user manual P.E.C.T. .R.A.T.I.O, D. .C.L.I.P.P.I.N.G

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S Y S T E M B A S I C S

Selecting and Displaying Windows–Serial Port Control

.A.S.P.E.C.T. .R.A.T.I.O.

P O S I T I O N I N G

.A.N.D. .C.L.I.P.P.I.N.G.

Example––define the destination rectangle in Figure 4. That is, place the top left corner of window 1 at (300, 700) of the display’s raster, and use a window 600 pixels wide and 250 lines high:

>wdr 1 300 700 600 250

The SuperView provides query commands that let you get the current value(s) of most system parameters.

Example––query the SuperView on the current WDR values for window 1:

>wdr 1

The system responds by listing the frame buffer coordinate values:

>300 700 600 250

Any desired rectangular portion of an input image can be displayed in the corresponding window. Also, the window itself can be set to have any rectangular shape and be any desired size on the monitor, up to the full size of the output raster. The size and shape of the source rectangle are independent of the destination rectangle’s size and shape. This has important consequences.

Let us suppose that you defined an input’s source and destination rectangles so that the central 320 pixels by 240 lines of a video source image were mapped into a 640x480 window. In this case, the destination rectangle is larger than the source rectangle, but has the same shape and the same width-to-height aspect ratio (4:3). Thus, the original input image is scaled equally in both dimensions for display on the monitor.

Varying the destination rectangle’s size but preserving its aspect ratio makes the displayed image larger or smaller. As long as its proportions correspond to those of the source rectangle, the displayed image will resemble the input image. If you independently vary the shape of either the source or destination rectangle, so that their aspect ratios are no longer the same, your displayed picture will appear stretched or squeezed compared to the original image. Figure 4 shows how the image is stretched by using a destination rectangle with a different, more elongated shape than that of the source rectangle.

A window can be positioned anywhere on the output raster. If the window’s destination rectangle is defined so that a portion of the window is off the screen, that portion of the windowed image is clipped (until it is moved back into view). This “image clipping” is illustrated in Figure 5. The window is positioned by specifying the screen coordinates of its top left corner. Negative coordinate values clip from the left and top edges of the window.

10 SuperView 3000 User Manual May 9, 2002