Raster And Vector File Formats Compare And Contrast Homework Essay Sample

The advent of Information and Communication Technology (ICT) has had a profound influence on art and art forms. The computer pervades all spheres of work and leisure and promises to become the most ubiquitous of all things. In the field of graphics too, art, paintings, sketches and photographs are being not only digitized, manipulated and enhanced, but also created, produced and disseminated through a wide range of hardware and software applications. Computer graphics both generated and digitized from conventional media are now posted on websites and reproduced in print and the electronic media in different forms, sizes and shapes. A photograph taken by a digital camera may, for example, be blown up to hundred times its original size and put up on a hoarding, a drawing generated by a software application may be replicated and manipulated and collated again to produce animation. In logo creation a computer graphic may be used in a wide variety of publicity and promotional material both electronic and hard print. In all these processes of conversion, modification and reconversion, the prime emphasis is however on quality, or to be more specific the resolution of the graphics.

Different types of media require different quality of graphics. While a low resolution photograph may be suitable for a website, a big banner advertisement would call for a much better quality graphics. All graphic designers would therefore have to have a very sound knowledge of the factors that affect the quality of computer graphics, they have to know which formats could provide them the quality standards that they are looking for within the constraints of a particular media. To be able to do so, the first and foremost requirement is to understand the two basic formats of computer graphics – vector and raster. To put it very simply, vector images are composed of connected lines expressed in mathematical terms; whereas, raster images are a collection of connected dots. Scanning of original or source artwork such as the hard print of a painting with some photo editing, print or scanner software such as Corel PhotoPAINT or Adobe Photoshop produces a digitized raster graphic. Vector graphics, on the other hand, are created when a vector illustration program such as CorelDRAW or Adobe Illustrator are used to draw or paint. In other words, raster graphics are usually the digital reproduction of an original source art, whereas, vector graphics are computer-created graphics. Raster graphics can also be converted to vector formats by using conversion programs such as CorelTRACE or EuroVECTOR.

Each of these formats has its own distinct advantages and disadvantages in relation to each type of media. The graphics belonging to each format have their distinct properties in the way that they are generated and in the ways that they can be modified or manipulated. “These two formats are quite different from one another, yet they contrast and complement one another when used appropriately for the desired final output method.” (Busselle, 2004)

Vector Graphics

Vector graphics utilize geometric modeling of images. Geometrical standards such as lines, curves and polygons are used to represent images in mathematical terms. The word vector is a synonym for line, which essentially implies that the vector format works on the depiction of lines through mathematical interpretations. Every line, curve and node in a vector graphic is defined by the software by a mathematical description with help of fixed co-ordinates. “A vector graphics file may be a database of object definitions or a sequence of instructions that are ‘played’ by an interpreter. The latter are often referred to as metafiles and are generally designed to be interchange formats. An example will serve to make things clearer.” (Westcott, 2005)

Adobe Illustrator uses a mathematical system called Bezier math, named after French automotive engineer Pierre Bezier, to define and locate the lines and shapes in a vector drawing. The system uses line elements that pass through defined anchor points to create line illustrations. The software plots the basic shapes that are drawn by listing them as numerical co-ordinates in pairs of x and y. After the co-ordinates are defined, the program draws the line elements between the points plotted. The software stores instructions to stroke the outlines of the shapes, to fill them or to do both. An element called the control handle is used when the shapes being drawn become more complex. This element stores information on how a curve passes through a particular anchor point and to which co-ordinates it would lead to. This enables Illustrator to have mixed sections of curves and lines. “The pairs of x,y coordinates, combined with the mathematical controller for curves and such are together called vectors. These vectors are solid mathematical values that even an accountant would appreciate. They don’t change (but they can be modified easily).”(Lawler, 2002) Vector graphics are object-oriented. Vector fonts are created by connecting the nodes, lines and curves of the text objects. Each letter of the font is considered as a vector object. Thus in vector graphics a wireframe is create under the colors of the object. The skeleton that makes up the object is clothed by the colors.

Vector images comes in a wide variety of extensions including EPS or Encapsulated PostScript, WMF or Windows MetaFile, AI or Adobe Illustrator, CDR or CorelDraw, DXF from AutoCAD, SVG or Scalable Vector Graphics and PLT or Language Plot File from Hewlett Packard. All these extensions are based on the software application packages that generate the graphics, and each come with its own advantage and unique feature.

Vector Advantages

Vector images can be scaled up or down without any loss in resolution because they are defined in mathematical terms, and increasing or decreasing the size of a graphics translates into something as simple as multiplying the mathematical description with a suitable scaling factor. Since scaling can be done in vector graphics without any loss in quality, these graphics can be printed at any resolution that the printing device is capable of. This makes vector graphics as preferred for clip art as for very large bill board images.

Unlike raster graphics which are dependent on individual pixels or units of colors, vector images are made up of objects. Changing the color of these objects could be as simple as clicking inside the object and defining its color.

The file size in vector images is comparatively very small because vector files comprise long mathematical descriptions detailing each aspect of the image or object. A change in size would imply only a change in a particular numerical value. Even a change in shape would add only to the mathematical description which by itself would not take up much of space. Vector image file sizes are therefore inherently small.

Raster Images

Raster images are made up of a collection of pixels. The pixel is the smallest unit of the raster image. The two words ‘picture’ and ‘element’ come together to form the term ‘pixel’. A pixel in a computer image actually contains information on the color and tonality of the corresponding spot in the source image. Monochrome information, duotone information and color information in RGB, CMYK and other color palettes can be represented by each pixel. The information stored against each pixel displays what the computer interprets as the actual color of the corresponding tiny part of the source image. Raster images are also called bitmapped images because each image is composed of rows of bits or pixels mapped or arranged into a pattern to finally render the source image in digital form.

Raster in German means ‘to screen’, which is appropriate for raster images as they are screened as a grid of pixels.  In computer graphics, raster images are used for analog photographic material or continuous-tone images that have been digitized by scanning. Raster images come with different extensions depending on the software application and compression method that have been used. These include, BMP or Windows Bitmap, PCX for Paintbrush, TIFF or Tag Interleave Format, JPEG or Joint Photographics Expert Group, GIF or Graphic Interface Format, PNG or Portable Network Graphics, PSD for Adobe Photoshop, and CPT for Corel PhotoPAINT.

Raster Characteristics

Raster images are not scalable. A raster image can be enlarged only to a certain extent, beyond which the image will show jagged edges. This happens because the pixels constituting the raster images get blown up as the image size is increased, and the edges of these individual pixels produce the jagged outline. The resolution of raster images is measured in dots per inch or dpi, and the actual output from the image is dependant on the resolution of the image irrespective of the printing device. For example if the resolution of a raster image is 300 dpi and it is printed in a printing device of 2000 dpi, it will actually print at 300 dpi and not 2000 dpi.

A large number of colors are required to render an accurate reproduction of the original source image. The human eye is usually not able to differentiate between an original and scanned image or of an art source if the scanning is done at 24-bit color depth or at 16 million colors. However, if the scanning is using a palette of 256 colors it would not be possible to reproduce the original accurately as a smaller range of colors is available to choose from. To overcome this hurdle a process called dithering or approximating colors that are not available is used by scanners. Though dithering approximates the original color in the image there is a visible deterioration in quality with the appearance of a distinct dotted pattern. The complexity of the process increases manifold when one attempts to change colors in a raster image. In such a case, the software application must not only be able to isolate the color or the range of colors that is sought to me modified, but should also be able to substitute the original colors with the desired colors. The biggest disadvantage of raster images is therefore in the inherent difficulties in editing or manipulating them.

Compared to vector images, the file sizes of raster images are comparatively higher because in raster image the software application has to store information on the exact location and color of each and every pixel in the image. The higher the resolution and the greater the color depth of the raster image, the bigger is the file size. File size becomes a handicap in the case of raster images as big files are especially not suitable for websites, and are difficult to transfer over the Internet. Even today in the days of high-speed broadband connections, it is difficult to transfer files over 1 megabyte over the Net.

Applicability

Going by the inherent characteristics of the two computer graphics file formats, it is advisable to use the vector format, whenever possible, in all type, line art and illustrations and use bitmap or raster graphics only for photos or images with complex or non-uniform shading.

The modern day computer artist however has to be able to work both with vector and raster images. The ideal page layout program would be basically a vector-based application which would be able to at the same time create, import display and print raster images side by side with the native vector images. Examples of dual usage can be found in application software such as Adobe Photoshop – an image editor – which incorporates vector based paths which can be exported as native vector files.  On the other hand, major illustration programs such as Deneba Canvas, Adobe Illustrator, CorelDRAW and Macromedia Freehand allow bitmaps to be embedded in the vector files they create.

Even in very diverse applications such as in the case of mappings of an earth observatory, images would be a combination of vector and raster with “annotations and continental outlines in a vector format (EPS) and data in a raster format (TIFF). Each covering the same area and with identical aspect ratios.” (Simmon & Sutton, 1998)

Conversion

A very interesting point to note is that almost all software applications dealing with graphics nowadays, including animation software and CADD applications, use vector format. Printers such as PostScript printers use vector graphics and PostScript fonts which are actually vector fonts. Since vector images are more scalable and malleable, converting rater to vector images lends then accessible to a greater degree of manipulation and wider range of application.

However, dot-matrix printers, laser printers and monitors are raster devices. This implies that all vector images have to be converted to raster before they can be printed out or displayed by the raster devices.  Therefore, conversion from vector to raster and also from raster to vector is required under different circumstances and situations. Conversion from vector to raster is more easily accomplished than conversion from raster to vector.

From Vector to Raster

To ‘rasterize’ means to convert a vector-based image to a bitmapped image. During this process, the mathematical formulas and geometric objects which make up a vector image are converted into groups of dots, using a specific resolution. Rasterization algorithms differ according to the shape of the geometrical elements of the image that is being converted to vector graphics. A triangle, a line, a polygon and a circle will all have their own vectorization algorithms. Once a vector file has been rasterized as a bitmap image, the resolution can not be changed without affecting the quality of the image.

From Raster to Vector

Raster images are transformed to vector drawings through a process termed as Vectorization. As raster images are inherently imprecise, the final vector output could vary widely in defining the exact number of vectors and the precise position of the co-ordinates from one conversion effort to another. It is therefore essential to employ well-established mathematical methods to take the variations into consideration and achieve the most precise conversion possible. Different conversion algorithms achieve these essentially through three basic approaches:

1.      Using automatic conversion software which traces the dots in the raster image and translates them to mathematical terms of a vector image. A large number of software is available for automating the process of conversion of raster images to vector formats. Adobe Photoshop and Illustrator both come with their plugins for vectorization.

2.      Manual underlay conversion specifically in CAD in which the raster image is inserted in a CAD application and the vectors are drawn over it in CAD.

3.      Manual Digitizing in which the mouse or pen of a digitizing table is used to manually trace over each original line of the raster image.

The manual methods are still utilized even though automatic conversion software are available because the automatic conversion software are not able to do a clean job, especially when the raster image itself is of low quality, and manual reworking is inevitably required.

One way of achieving better vectorization is to convert all colors in the raster image to grey scale prior to the vectorization. This enables the vectorization method to differentiate between pixels that belong to the main image and pixels that belong to the background.

Vectorization also resorts to a process called negation. In negation, all the colors in the image are first converted to their corresponding photo-negative color. This is particularly useful for the vectorization of a blueprint or other negative-based originals where the lines are lighter in color than the background. In the simple edge detection method of vectorization, a negative image can be more effectively used in the case of a black and white raster image where the outer edges instead of the inner edges of the objects can be obtained. The brightness of objects is also adjusted in raster to vector conversions because such adjustment changes some pixels to background intensity and vice versa.

Despeckling is a process is a process which produces an image which does not have clusters of pixels that distorts the image and results in an inaccurate vector. Despeckling cleans up dirty scanned images with dark speckles which are not a part of the image.

Vectorization finds a wide variety of applications. In paper-to-CAD conversion or drawing conversion, Computer-Aided Design (CAD) drawings such as blueprints are first scanned as raster images and then vectorized and stored as CAD files which can processed and manipulated.

In Geographic Information Systems, maps are created by vectorizing satellite or aerial images. Vectorized photographs can be easily integrated into geometric designs such as logos.

Conclusion

Every person who works with computer graphics therefore has to master the art of working both in raster and vector formats. Options for conversion from raster to vector and vise versa are available if the situation so warrants depending on the type of media that the work is to be displayed in.

References

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Busselle, J., 2004, Raster Images versus Vector Images, [Online] Available. http://www.signindustry.com/computers/articles/2004-11-30-DASvector_v_raster.php3 [June 04, 2009]

Lawler, B., P., 2002, Vector that, Charlie. A quick study in file types, history, metaphors and apple pie, San Luis Obispo, California

Simmon, R., Sutton, M., 1998, Image Formats: Vector and Raster, NASA.

Westcott, K., 2005, Preservation Handbook, Vector Graphics, AHDS Preservation Handbook, Arts and Humanities Data Service.

 

Coursework On The Rascal King (James Michael Curley-Boston) By Jack Beatty

                James Michael Curley was a colorful figure in the history of Boston and he left a mark, good or bad in the history and culture of that state during his political carrier, which lasted for fifty years. He was elected governor, mayor, congressman, and alderman of the state during his political life. He did not have any neutral supporter. Either some people used to consider him as a hero, or some used to consider him as a worst villain of the century. He was the only mayor in US who was thrice indicted and jailed twice. (McDonough, 1)

                   For this reason, Jack Beatty has described him in his book as “The Rascal King”. Beatty has tried to find out the reason that why, in spite of being such a worthless person, he was elected by the people of Boston over and over again. Beatty has described Curley in the book as “The Rascal King”. During his political carrier, Irish people were migrating to the United States and settling down in Boston area. The book reflects the complexities of the urban politics of that time. “For the Irish Americans…he was a political and cultural hero, an axial figure in their annals…the main thread in Curley’s public life: doing little things for little people who repaid him in votes and gratitude, who as the years went by and they tasted something of the world’s indifference, magnified manifold the value of the little things Curley had done for them” (McDonough, 1)

                     Describing the rule of Curley, Beatty has actually covered a journey, describing hundred years of Boston history and in the process, he was always critical about the activities of Curley. The book deals with Irish immigration into the US and their history.

                                 Irish Protestants started arriving in the United States in the mid 18th century as they were becoming frustrated by the difference of the Presbyterians in Ascendancy Ireland. Their numbers increased after the failed revolt of Wolf Tone in 1798. On the contrary, Irish Catholic immigration started from the beginning of the 19th century. But their immigration greatly increased towards the middle of the century when the Great Famine occurred in Ireland. It forced about a million and half people to leave the island. Thomas H. O’Connor has mentioned these in his article The Boston Irish: A Political History.

                       Thomas H. O’Connor has also mentioned in his article that the Protestant immigrants left Ireland and migrated demanding land and political rights. As they used to speak English it became very easy for them to adjust in any new place that offered land and opportunity. Hence, many of them became well settled soon in the lands occupying the Western Frontier.

                   Irish Catholics on the other hand were not so fluent in English and were forced to leave Ireland and immigrate because of economic reasons and physical hunger.  They were very much socially dependent on each other in this new found world and suspicious about everything around them. Their level of suspicion was same as they used to have towards the English speaking landlords and government officials in their native home. This wave of economically backward immigrants settled in ethnic ghettos in the northeastern cities. Thomas H. O’Connor has mentioned these in his article The Boston Irish: A Political History.

                 It has also been stated in the article by Thomas H. O’Connor that massive presence of Irish Catholic population led to a conflict for the first time in the history of the US between the natives and legal ethnic immigrants. To quote from the website, “Based in the ghetto network of churches, clubs and bars, the sometimes ruthless and always populist ethnic class politics of Irish party bosses would turn out to be an effective strategy against Anglo-American ‘brahmins’.”

Thomas H. O’Connor was very much critical in his article to mention that just with their vast numbers and well oiled infamous political machinery, their aim was to capture political power and in the process, getting their various interests served from the municipal government and also forcing the Irish Protestants yield to their political power. With a like minded Mayor Curley in office, their aim was to use the political power for further “social and economic aspirations”.

                   Thomas H. O’Connor has mentioned in his above mentioned article that for nine decades the Irish enjoyed a massive political monopoly in Boston, like Americans in any other American city. In this unbroken reign of Mayors, there arrived ghetto populists like James Curley who dominated the political scene in Boston during the first four decades of the twentieth century.

                 Jack Beatty has described in his book The Rascal King this urban politics of Boston and how it helped an inefficient person James Curley to get elected so many times by the voters of this region. To quote from the Chapter The Shin of a Sparrow Page 21 of the book, “The instrument of their remembrance would be James Michel Curley, who would reach back beyond his father’s generation to reclaim for politics the ethnic bitterness stemming from the events of the fifties that had been kept out of politics for decades. It would be what lent them the sullen psychology of an aggrieved minority long after they had become a majority.” (Amazon.com book reading section)

                Thomas H. O’Connor has also stated in his article that these Irish Catholics used to live in their ethnically insulated neighborhoods and had very limited social exposure. Out of these, they would feel betrayed at some things and created an objection on the path to development. They used to protest against the urban development policies initiated by their elected Mayor based on the fear that it may come as an attack on their ghettos which once had given them some identity and the force and security to live as a group. The author has mentioned in his article that they tried to enforce racial integration in municipal schools by sending their children in buses from the ethnic ghettos.

               Describing the generation that Curley belonged to as someone who “look back to pick up”, Beatty feels that it is the generation that never progressed and it is because of this reason that they prevented from going forward. Beatty has also stated in the Page 22 of his book that this “Famine Irish” people were undigested and indigestible and they came in a city where they were not asked to come. These words are a reflection of the fact that Beatty has openly expressed his hatred towards the Irish community as a whole.

                   It can be seen that Beatty has stated in Page 22 of his book that before the arrival of these Irish Catholics, Boston was a clean and ‘salubrious’ place and after they came, it became dirty and noisy. He has also stated that before their arrival, Boston was a unified lot and after these people arrived, the question of social divisions arose. To quote from the text on page 22, “Boston had stood for religion and politics; now it is a home to reactionary religion whose official organ, The Pilot, called the sacred cause of abolition ‘niggerology’.”

               McDonough has stated in his article that in a democracy, a nation gets the politician it deserves. To quote from his article, “At the same time–paradoxically–the opposite is also true: society is a mirror of its politicians. Politicians are indeed a mirror of their society, and a kind of embodiment of its potential. ” That is exactly what Jack Beatty has tried to describe in his book The Rascal King.

                   Describing the urban politics of a place for a specific time period, it is better to be narrative while describing the events and leave the conclusion in the hands of the readers. The way Beatty has expressed his words against the Irish Catholic, is very much unwanted from a writer of his stature. I was getting confused at some places, feeling that Beatty is a political opponent of Curley. You can blame the policies of a particular ruler or a mayor or a politician, but it is always unwise to blame an entire community for the misdoings of Curley.

                   After Second World War, many modern politicians like John B. Hynes, John F. Collins and Ray Flynn became the mayor of Boston and succeeded in developing a new Boston. The same Irish people voted them. It is always unfair to blame an entire community for that.

Works Cited

  1. The Boston Irish: A Political History, Boston: Northeastern University Press, 1995, Thomas H. O’Connor: Nordic Irish Studies Network: 10th March 2009 : http://www.hum.au.dk/engelsk/nisn/reviews/oconnor.html>
  2. The Rascal King: The Life and Times of James Michael Curley. – book reviews, Feb 12, 1993, John E. McDonough: Bnet Network : 10th March 2009 :  <http://findarticles.com/p/articles/mi_m1252/is_n3_v120/ai_13434671>
  3. Amazon.com book reading section: Look Inside Category : 10th March, 2009 <http://www.amazon.com/reader/0306810026?_encoding=UTF8&token=1ED1aEZdZpactj7ztckChMJhoy02k1gymx0qxRZIygjWfDXHpbSMRw&query=urbanpopulist&page=132>

On Raskolnikov’s Trial In Fyodor Dostoyevsky’s Crime And Punishment

Question Number One

On July 1865, Rodion Raskolnikov allegedly murdered both Alyona Ivanovna and Lizaveta Ivanovna, in the process stealing both women’s money and valuables in their apartment in St. Petersburg. After twelve days, Raskolnikov confessed that he committed the crime to the police. As Raskolnikov’s defending attorney, one may make a plea of insanity which is based on the assumption that Raskolnikov was “not responsible for (his) criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of law” (Model Penal Code 4.01(1)). Raskolnikov’s insanity may be affirmed by calling forward the following witnesses: Raskolnikov, Razumikhum, Mme Raskolnikova, and Raskolnikov’s sister.

           Raskolnikov may stand as a good witness to prove his insanity as he may relate his inability to distinguish reality from his delusions. Consider for example that within Crime and Punishment, he himself notes that he may have merely adopted what he heard as he passed through the house of Alyona and Lizaveta Ivanova. He claims that it would have been possible that he merely placed himself within the position of the murderer due to his inability to distinguish whether he was merely a spectator of the crime or a participant within the crime.

           Raskolnikov’s mental illness may also be affirmed by his friend Rasumikhum who has seen him in a “feverish condition, delirious, and half-conscious” before and after the murder occurred (Dostoyevsky 136). Rasumikhum may thereby enable the jury to be persuaded on Raskolnikov’s claim that he was not certain whether he committed the crime or merely adopted the position of the murdered since he affirm that Raskolnikov was not his usual self before and after the crime occurred.

           In addition to this, Mme Raskolnikov may also affirm the her sons mental illness as a result of her admission that she sent a letter to Raskolnikov before the murder occurred that may have led him to lose his mental stability and hence his control over his senses. In addition to this, Mme Raskolnikov herself notes that when she arrived in St Petersburg, she saw “something unbending and almost insane” in her son which led her to tears (Dostoyevsky 126).

           Raskolnikov’s sister may also be called in to affirm that their mother sent a letter to Raskolnikov that may have caused him to lose mental stability due to her past knowledge that her brother possesses a highly fragile nature that may lead him to break as a result of receiving the news that his family will place themselves in a difficult position in order to sustain his needs.

Question Number Two

           Given that Raskolnikov was convicted of first degree murder and voluntary manslaughter, to resort to the plea for insanity may still lead to Raskolnikov’s conviction. The reasons for these are as follows: (1) Not everyone believed that Raskolnikov was insane [consider for example Sonya and detective Porfiry], (2) Although Raskolnikov was portrayed as an individual prone to insanity within the text, he was also depicted as an individual who thinks rationally and systematically hence one may question whether Raskolnikov really did lose his state of mind during the occurrence of the murder. In addition to this, one may also argue that Raskolnikov acted in such a way that he was deranged during his encounters with Rasumikhum since he knows that there is a large possibility that Rasumikhum may be called in as a witness for his defense. (3)Finally, Raskolnikov himself confessed that he committed the crime and was repentant about his actions. To admit and to state that he was repentant about his actions would merely affirm that he was in full control of his mental capacities during the time that he committed the act.

Works Cited

Dostoyevsky. Fyodor. Crime and Punishment. New York: Signet Classics, 1999.

Model Penal Code, 11, § 4.01.