by Dinesh Thakur Category: Graphics Devices

This was one the earlier CRTs to produce color displays. Coating phosphors of different compounds can produce different colored pictures. But the basic problem of graphics is not to produce a picture of a predetermined color, but to produce color pictures, with the color characteristics chosen at run time.

 
by Dinesh Thakur Category: Graphics Devices

Conceptually the Direct View Storage Tube (DVST) behaves like a CRT with highly persistent phosphor. Pictures drawn on there will be seen for several minutes (40-50 minutes) before fading. It is similar to CRT as far as the electronic gun and phosphor-coated mechanisms are concerned. But instead of the electron beam directly writing the pictures on the phosphor coated CRT screen, the writing is done with the help of a fine-mesh wire grid.

 
by Dinesh Thakur Category: Line Drawing Method

On the Macintosh, some programs let you edit bitmapped graphics as FatBits. In FatBits mode, the individual dots, or pixels, making up the image are blown up so you can work with them easily, one at a time. If you see stray dots in an image you've scanned, or if a line in a picture is just slightly too thick or too skinny, it's almost impossible to make precise changes working at normal size.

 
by Dinesh Thakur Category: Line Drawing Method

A typical black-and-white photograph uses only one color. In a duotone, though, the black-and-white photograph (or other artwork) is reproduced using two colors. Perhaps it's black and brown, or black and grey, or dark grey and a rusty color. Halftone images are generated for the photograph, one slightly underexposed and one slightly overexposed, and the two are printed one on top of the other. The result can be an incredibly rich, powerful image-much richer and more interesting than the image with one color. The artist/designer has control over the values and percentages of the two different colors. It is also possible to make "tritones" using three different colors, and "quadtones," using four different colors.

 
by Dinesh Thakur Category: Line Drawing Method

Whenever a photograph, painting or drawing containing many colors or gray tones is printed, the colors and tones must be simulated with tiny dots. Dot gain refers to an increase in the size of these dots when they are actually printed on the paper by the printing press. The dots can increase in size rather dramatically once the ink hits the paper, depending on the characteristics of the press, the absorbency of the paper, and the nature of the ink that is used.

 
by Dinesh Thakur Category: Line Drawing Method

When text or a graphic image is displayed on amonitor,or screen, the smoothness of the edges is limited by the resolution of the screen, which means the edges tend to be a little jagged. This jaggedness is also called aliasing.

 
by Dinesh Thakur Category: Line Drawing Method

A mathematical point (x, y) where x and y are real numbers within an image area, needs to be scan converted to a pixel at location (x’, y’). This may be done by making x’ to be the integer part of x, and y’ to be the integer part of y. In other words, x’ = floor(x) and y’ = floor(y),

 
by Dinesh Thakur Category: Line Drawing Method

You know that a line in computer graphics typically refers to a line segment, which is a portion of a straight line that extends indefinitely in opposite directions. You can define a line by its two end points and by the line equation y = mx + c, where m is called the slope and c the y intercept of the line. Let the two end points of a line be P1(x1, y1) and P2(x2, y2). The line equation describes the coordinates of all the points that lie between the two endpoints.



 
by Dinesh Thakur Category: Line Drawing Method

DDA algorithm is an incremental scan conversion method. Here we perform calculations at each step using the results from the preceding step. The characteristic of the DDA algorithm is to take unit steps along one coordinate and compute the corresponding values along the other coordinate. The unit steps are always along the coordinate of greatest change, e.g. if dx = 10 and dy = 5, then we would take unit steps along x and compute the steps along y.

 
by Dinesh Thakur Category: Line Drawing Method

You know that DDA algorithm is an incremental scan conversion method which performs calculations at each step using the results from the preceding step. Here we are going to discover an accurate and efficient raster line generating algorithm, the Bresenham's line-drawing algorithm.

 
by Dinesh Thakur Category: Two Dimensional Transformations

The process by which CONTINUOUS TONE photographs are reproduced in print (for example in newspapers and magazines) by reducing them to a grid of tiny dots. (The resulting image is also commonly known as a halftone.) Each individual dot is printed using a single coloured ink of fixed intensity, and the intensity of colour the reader perceives is controlled by varying the size and density of the dots to reveal more or less of the underlying white paper.

 
by Dinesh Thakur Category: Two Dimensional Transformations

An algorithm employed in 3D GRAPHICS to fool the eye into seeing as a smoothly curving surface an object that is actually constructed from a mesh of polygons. Gouraud's algorithm requires the colour at each vertex of a polygon to be supplied as data, from which it INTERPOLATES the colour of every PIXEL inside the polygon: this is a relatively fast procedure, and may be made faster still if implemented in a hardware GRAPHICS ACCELERATOR chip. 

 
by Dinesh Thakur Category: Two Dimensional Transformations

Ray tracing is an incredibly complex method of producing shadows, reflections, and refractions in high-quality, three-dimensionally simulated computer graphics. Ray tracing calculates the brightness, the reflectivity, and the transparency level of every object in the image. And it does this backwards. That is, it traces the rays of light back from the viewer's eye to the object from which the light was bounced off from the original light source, taking into consideration along the way any other objects the light was bounced off or refracted through .



 
by Dinesh Thakur Category: Two Dimensional Transformations

To understand what rasterizing does, first you need to know a little about the images in the computer: Bitmapped (raster) graphics and fonts are created with tiny little dots. Object-oriented (vector) graphics and fonts are created with outlines. Output devices, like printers (except for some plotters) and monitors can only print or display images using dots, not outlines. This means that when an object-oriented graphic or font is output to a printer that prints in dots per inch (as most of them do) or to a monitor that displays in pixels (as most of them do), the outlines must be turned into dots. This process of turning the outlines of the objects into dots is called rasterizing. Everything you see on your monitor has been rasterized. Everything you print has been rasterized.



 
by Dinesh Thakur Category: Two Dimensional Transformations

Some computer screens are grayscale, rather than plainblack-and white (monochrome). On a black-and-white screen, there is only one bit of information being sent to each pixel (dot), so the pixels on the screen are either on (white) or off (black). On a greyscale monitor, anywhere from 2 to 16 bits of information are sent to each pixel, so it is possible to display gray tones in the pixels, rather than just black or white.



 
by Dinesh Thakur Category: Two Dimensional Transformations

On a piece of photographic film, such as the kind you use to shoot photographs, one side of the film is coated with a layer of chemicals called the emulsion. This is the side that absorbs the light, and the emulsion is scratch able and dull. The non-emulsion side of film looks shinier and is more difficult to scratch. You can see the emulsion side on any negative you have hanging around.

 
by Dinesh Thakur Category: Two Dimensional Transformations

Early computer-generated images used shaded objects that had unnaturally smooth surfaces. To produce a textured surface using the techniques discussed would require creating an excessive number of surface pieces that follow all of the complexities of the texture. An alternative to the explosion of surfaces would be to use the techniques of texture mapping. Texture mapping is a technique used to paint scanned images of a texture onto the object being modeled. Through an associated technique, called bump mapping, the appearance of the texture can be improved still further.

 
by Dinesh Thakur Category: Two Dimensional Transformations

A problem with the Painter's and Z-Buffer Algorithms is that they ignore the effects of the light source and use only the ambient light factor. Flat shading goes a bit further and includes the diffuse reflections as well. For each of the planar pieces, an intensity value is calculated from the surface normal, the direction to the light, and the ambient light and diffuse coefficient constants. Since none of these changes at any point on the piece, all of the pixels in that piece will have the same intensity value. The resulting image will appear to be faceted, with ridges running along the boundaries of the pieces that make up an object.

 
by Dinesh Thakur Category: Two Dimensional Transformations

An extra layer of information stored in a digital picture to describe transparency or opacity. For each pixel, the alpha channel stores an extra value called alpha, in addition to its red, blue and green values, which indicates the degree of transparency of that pixel.



 
by Dinesh Thakur Category: Two Dimensional Transformations

What is transformation? In  many  cases  a  complex  picture  can  always  be  treated as  a  combination  of  straight line, circles, ellipse etc., and if we are able to generate these basic figures, we can also generate combinations of them.  Once we  have drawn these pictures, the  need arises  to transform these pictures. 

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.