Design Skills - Resources and Training for Designers

Graphics
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Although traditionally considered a lesser art, graphic design has become at the core of our culture and touches every area of our lives, from packaging, logos to road signs and posters to name but a few. In the last century, not only have we experienced a shift in the status and uses of graphics but also in the way they are produced. It is most likely today that graphic designers will be working using advanced computer software rather than hand based methods.

| Operation | Bitmap images | Vector graphics | Selection |

Operation

From a technical point of view, there are a few basic points to remember when creating graphics: intended use, quality an size. For example, is the graphic for print or the web? Although professional laser printing requires a minimum of 300dpi (dot per inches), 72pi is recommended for screen and website graphics. In websites, the graphics are further optimised to keep the size as small as possible to minimise download times.

Will the size of the graphic fluctuates? A company logo may appear quite small on a letterhead but will need to be printed at a very large size on the company vehicle. To be able to achieve this, it is best to use VectorGraphics rather than Bitmap images.

Computer images can be either in bitmap (not to be confused with the file extension .bmp) or vector format. Every Adobe Photoshop ® image, for example, is a bitmap, whether it originates form a scan, another application or was created in Photoshop ®. Other software such as Adobe Illustrator ® use the vector format.

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Bitmat images
Bitmap images - technically called raster images - are made up of a grid of dots known as pixels. When working with bitmap images, you edit pixels rather than objects or shapes. Bitmap images are the most common electronic medium for continuous-tone images, such as photographs or digital paintings, because they can represent subtle gradations of shades and colour.

Bitmap images however can lose detail when scaled on-screen because they are resolution-dependent, they contain a fixed number of pixels, and each pixel is assigned a specific location and colour value.

Bitmap images can look jagged if they're printed at too low a resolution because the size of each pixel is increased. Pixels are a geometric arrangement (mapping) of a layer of dots of different shades or colours on a rectangular grid. Each pixel represents a colour or shade.
Bitmap image - Click on the thumbnail to view a larger image
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Vector graphics

Vector graphics are made up of mathematically defined lines and curves called vectors.

This means that you can move, resize, or change the colour of a line without losing the quality of the graphic.
Vector Graphic - Click on the thumbnail to view a larger image

Vector graphics are resolution independent, they can be scaled to any size and printed at any resolution without losing detail or clarity. As a result, vector graphics are the best choice for representing bold graphics that must retain crisp lines when scaled to various sizes.

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Selection

Bitmap images and vector graphics are also selected differently. When selected, bitmap images display selection handles at each corner. Vector graphics however, also display vertex or anchor points, which can be further manipulated. Adobe Illustrator ® for example, uses the selection tool for standard selection but the direct selection tool and convert anchor point tool for vertex selection.
Bitmap selection - Click on the thumbnail to view a larger image
Vector selection and manipulation - Click on the thumbnail to view a larger image


Adobe Photoshop ® on the other hand uses the marquee tools, lasso tools and magic wand tool to select pixels in an image or part of an image. The selection is represented by the dotted lines.
Bitmap pixel selection - Click on the thumbnail to view a larger image
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Skills CAD Training

> About CAD > Scale > Basic Geometry > 2D Drafting > 3D drawing > The Overlay Method > Graphics > Image Editing


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