However vector graphic conversions are usually more tricky, and the results usually less satisfactory. Vector document sizes thus depend on the complexity of the drawings within them, not their scale.Ĭonverting between different pixel-based image formats is not difficult, and many image editors and painting apps cope happily with all the more popular types. To scale that up by a factor of 10, the co-ordinates of the points are scaled by 10, and the file remains identical in size. Which draws a straight line between those points. A vector-based drawing, though, consists of resolution independent commands, such as Although compression can limit this, doubling the linear dimensions of an image will normally increase the disk space by a factor of four, the square of the increase in linear dimension. The larger a pixel-based image is, the larger the file required to store it. When accelerated by the graphics card, Quartz 2D becomes known as ‘Quartz Extreme’ or ‘QuartzGL’, and is the standard required from Mountain Lion onwards. To make this more powerful still, OS X provides an additional layer of support in Quartz 2D, which handles the drawing of text, PostScript and PDF, and colour management using ColorSync. When an application wants to render a spline curve, it merely generates the OpenGL commands needed to define and render the splines, and the graphics card does the rest. OS X contains extensive support for both pixel- and vector-based graphics, and in all modern Macs graphics primitives and more sophisticated drawing and rendering commands are delegated to the specialist hardware in the graphics card, using OpenGL or (most recently) Metal. Although the letters may be illegible when zoomed out at 25%, they should be distinct at 100% or more, and rendered smoothly. The document does not contain the text content either, so you cannot alter the text except by changing the pixels.Ī vector-based image contains the text, which remains editable, and renders that appropriately to the level of magnification. Zoom into it and it becomes blurred or pixellated like the rest of the image. In a pixel-based image, text is just an area of pixels of different colours. This distinction is even more clearly visible in the rendering of text. Instead of consisting of a large array of individual pixels, the vector graphic file is made up of curves, lines, polygons, and other geometric components. You can then edit the control points and vectors that make up the whole curve, and the software renders it with anti-aliasing. ![]() Once fixed into the pixels you cannot readjust the curve in any way.Ī vector-based drawing application builds that curve using geometric constructions such as a series of Bézier or spline curves. Working in a pixel-based application, if you sketch in an arbitrary wiggly curve with anti-aliasing, the software will paint in the pixels that constitute the backbone of the curve in the active colour, then apply anti-aliasing to those pixels immediately adjacent to the curve to make it appear fair and not jagged. ![]() Vector information is also commonly found in popular compound formats, which can contain images as well, such as PostScript, and its derivatives Encapsulated PostScript (EPS) and Adobe Acrobat Portable Document Format (PDF), Flash’s SWF, and Apple’s old QuickDraw PICT. Vector file types include Scalable Vector Graphics (SVG), AutoCAD Drawing Exchange Format (DXF), and the venerable HP Graphics Language (HPGL). (Unfortunately I cannot illustrate this directly here, as SVG vector graphics are not a supported format in these blogs.)Ĭlassical pixel-based document formats include JPEG, TIFF, GIF and its replacement PNG. Once an image is shown at 200% or greater, you can see that it is an array of individual pixels, but vector graphics should remain crisp and smooth even at 1000% or more, as the computer renders each line and curve in the fairest way possible. One very visible insight into the differences can be obtained by zooming in repeatedly on the document. The drawn chessboard, on the other hand, is an assembly of regular squares, each filled in black or white, and can be broken down into those constituents, allowing them to be rejigged and the drawing change. The image contains areas of very dark pixels, and others of very light pixels, but has no sense of structure, of the lines or shapes that make up that image. These are most apparent when you look at an image of a chessboard, and one created using a drawing application. With so many images being passed around social media, it is easy to overlook the power and value of the other type of graphics, based on vectors instead of pixels.įrom the earliest days of computer graphics, distinction has been drawn between pixel-based images and vector graphics.
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