Free Essay

Image Dithering

In: Computers and Technology

Submitted By tobytonz
Words 970
Pages 4
Image Dithering

Image and its parameters
An image is a two-dimensional representation of a rectilinear array of pixels. A pixel is sample point in the image that has coordinates location it. These samples are obtained from the continuous function CCD cells in a camera, photoreceptors in the eye and rays in a virtual camera. There are three types of image resolution. The first resolution is where each pixel has only the depth bits for color or intensities. The second type of resolution is the spatial resolution which involves the width and the heights of the image only. Lastly, another image resolution is the temporal resolution, and this kind does the monitoring of the image brightness at a particular frequency only.
Image dithering
Dithering is the approximation of color from a mixture of several colors by the computer program when the desired color is not available. An example if dithering is the when a certain color in the Web page for a particular browser is not supported by the other. In that case, the browser will attempt to replace the desired color by approximating two colors that it can generate. The same may or may not be accepted by the designer of graphics and may appear grainy because it is composed of varied pixel intensities instead of one intensity.
Dithering has applications in color image output and for artistic purposes as well. Secondly, dithering is used in web design for reducing images from high color counts to low color counts. It is also used in reducing file size and bandwidth without harming the quality of the image file. Moreover, the technique is used in reducing the 48 or 64bpp RAW-format digital photos for editing ("Image Dithering: Eleven Algorithms and Source Code", 2012)

Basic Concept of Dithering
The main activity in dithering is error diffusion. For example, in reducing a gray scale photograph to black and white to enable printing on a printer that can support black and white pure inks only. The first pixel of the image has a value of 96 on a scale of 0-255 and is dark gray in color. The zero is pure black, and 255 is pure white. Consider figure 1 below

Figure 1: RGB visualization ("Image Dithering: Eleven Algorithms and Source Code", 2012)
The conversion of this pixel to a black and white scenario, a simple formula is used. The question is whether the color is closer to black or white. In this case, the value of 96 is closer to zero hence it is closer to black and the pixel is made black. The standard concept will involve the movement to the next pixel and perform a similar comparison. In error diffusion, the error in each calculation is spread to the neighboring pixels. If a 96 gray pixel is found, the value is determined to be closer to 0 than to 255 and the pixel is made black. The algorithm takes the note of the error in the conversion ("Image Dithering: Eleven Algorithms and Source Code", 2012)
The process involves the addition of the error of the previous pixel to the current pixel as it moves to the next level. If it finds that the next pixel is also gray, the algorithm will add the error of 96 to the previous pixel instead of just forcing to black as in the first case. The resulting value is 192 which makes it closer to 255 and closer to white and this pixel is made white and the error is noted. The error becomes -63 since 192 is 63 less than 255. This process of algorithm continues making an alternate of black and white pixels. However, this form of error is one dimension and involves the error diffusion is one direction only. In two dimension dithering, the error diffusion is done forwards and backward to produce a quality image.
Forms of Dithering and their appropriate algorithms.
Floyd-Steinberg Dithering
This is the famous type of dithering that uses the following pattern in dithering images: X 7 3 5 1 (1/16)
The notation ‘X’ means the present pixel and the fraction show the error divisor. In another version, the same formula can be rewritten as: X 7/16 3/16 5/16 1/16
In the previous example, if the pixel is forced to black, an error of 96 is generated. If the same error is propagated to the neighboring pixels to by diving by 16 and multiplying by some values as shown; X +42 +18 +30 + 6
When the error is spread to multiple pixels each having a different value, any distraction bands are minimized ("Image Dithering: Eleven Algorithms and Source Code", 2012)
Jarvis, Judics, and Ninke Dithering
This is a more powerful dithering algorithm than Floyd and Steinberg dithering technique. The method has a more complex pattern like this: X 7 5
3 5 7 5 3
1 3 5 3 1 (1/48)
With this kind of algorithm, the errors can be distributed as many times as possible. It is three times as many pixels as in the case of Floyd and Steinberg, and this results in a much smoother and subtle output. The disadvantage of this approach is that a small speed gain is propagated by multiple times.
Stucki Dithering
This type of dithering has improved processing time than the JJNs dithering. The algorithm of error processing is seen to has an improve complexity. This is shown below

X 8 4 2 4 8 4 2 1 2 4 2 1 (1/42)
The bit-shifting can be used to derive the exact values for propagation when the divisor divides the error. The method has a slightly higher speed than the previous approach, and this is why it is preferred ("Image Dithering: Eleven Algorithms and Source Code", 2012)

Similar Documents

Free Essay

Upheld by Character

...Upheld By Character Character is built upon strength and compassion. To be quite honest, I happened upon this photo as I was rummaging through the mountains of pictures my mother has collected over the years. To my knowledge, I have never seen this before but I feel as though this photo gives an extremely detailed overview of my life. The fate of most photographs usually consists of being overlooked and cast into the attic, yet every picture is a reminder of an important memory. However, photos such as school pictures, which can be seen throughout my house, seem useless to me. Often times in these pictures emotion tries to be built or controlled. A moment deserves to be captured when the subjects in it find themselves unable to hold back a smile or a prideful smirk not when one is forged. What good is a memory if it lacks emotion, the backbone of a picture? It is obvious that in my picture we are not overtaken by joy, however, emotion engulfs this photo. Determination and faith can be found in this mirror of a memory. My father has his hands around mine, preventing me from falling into the abyss. Maybe to an average person it would be called a swimming pool, but convincing the 3 month old version of myself that that was true would be quite a feat. This second nature act of protection is not what drew me to this photo. It was no great accomplishment to stand on the first step of the pool, true. A father has an innate desire for the well-being of his child, also true. But......

Words: 618 - Pages: 3

Free Essay

A Student Who Cheated

...This is about my still image analysis of my pictures I posted on Facebook. On Facebook I have posted some pictures that are semiotic. Semiotics is the study of signs. This may includes signs devised to convey meanings “....language, badges as well as 'symptoms' as in that’s the sign of swine flu'”. (Branston 12) Potency involves the strong or weak signs of semiotics that appear in the image. The sign in this image is that of me wear a suit with a sign of economic stature, which is the definition of symbolic sign. Most people where suit like the one I have in the picture and have some type of corporate job and make very good money. This makes the image a connotative image it represents an idea or mental image of a thing rather than the thing itself. The denotative meaning of the image is a guy in a nice suit poses to get his picture taken. The definition of denotative is the literal meaning of what you see in the picture. When I post this picture on Facebook the audience for whom the picture was for was my Facebook friends. My mom somehow saw it and she doesn’t have a Facebook account. Then I realize some of the people who are my Facebook friends are also her co workers and they commented on the picture. I don’t really care who sees the picture because it’s my own personal count with some friends and family members. What I hope people get out of this is that I look nice in a suit and tie. I look at it more like a professional selfie form a distance as it was shoot by a......

Words: 522 - Pages: 3

Free Essay

Friends with Benifits

...Research Essay 1 This essay is to be no less than 2 pages long. Susan Sontag’s essay Regarding the Pain of Others brings forth many atrocities of war. I would like you to choose an atrocity mentioned in the essay which will be the basis of your research paper. As you research you will come across pictures and photographs that are suppose to “show” you what was occurring during the time of the atrocity; however as you view such photographs I would like you to address ONE of Sontag’s ideas below which will become your essay topic: 1) Photographs do not assist in the comprehension of a situation, that is up to writers to create narratives that help in understanding 2) Meanings from photos are free floating, and can only be grounded by words 3) The photograph is not an objective mirror, but an expressive medium capable of portraying multiple realities. 4) Intentions are not inherent in photography, meaning is situational and in flux – this is in keeping with the previous key idea. The photograph itself is capable of “speaking” for itself only so much. It requires an interpreter. And it is the agenda of this interpreter that the photograph assumes. The photograph itself has no agenda; it takes on the one of who is interpreting for it. Part Two You are to create a power point presentation of the atrocity you discussed in your research paper which is to include both pictures and text. You may also choose to streamline......

Words: 267 - Pages: 2

Free Essay

French Revolution and Painting

...Mashell Chapeyama Topic: Art History Year 2012 Level: Bachelor of Science in Business Administration The French revolution and Painting The French revolution had a big impact on art. It brought in new themes to art. The following are some of the themes that emerged: • Democracy • Reconciliation • Patriotism • Rising against unfair rulers • Battle-scenes Some paintings that emerged from the French revolution heightened the need for democracy. Before the revolution most nations were ruled by dictators, most of whom were monarchies. For example there were some paintings that showed the democratic legacy of Greece and Rome. Patriotism was also portrayed. For example the picture entitled the Coronation of Josephine. This was a great piece of art. The painter wanted to illustrate that Napoleon was the legitimate ruler of France. The earlier paintings related to this showed the sketches of Napoleon crowning himself. On the other hand the picture of Gericault showed how people can attack the government. It has some revolutionary connotation. It seemed like inciting people to fight mistrusted rulers. Some pictures showed what happened in wars. One painting shows Napoleon crossing the alps on his horse. This showed his victories in wars. Napoleon was a successful fighter. The other pictures show the people fleeing from battle fields. Some were refugees fleeing their homes. One painting of David show what happens in revolutions. It was entitled, “Oath of Horiatis”. It......

Words: 386 - Pages: 2

Free Essay

A Dog

...the left side of the brain, there will be a jump in amplitude where the lesion occurs, something like: 3. Ultrasonic B-scans are used to create 2-D cross sectional images of the structure of interest. A solid ball would create merely a filled in circle; a tennis ball filled with air would create an image of a outer rim with empty space inside, as shown below: 4. The three controls that a technician uses on an x-ray machine are the voltage adjustment, mA control and the exposure timer. The voltage adjustment is used to control the penetrating power of the beam. A greater penetrating power will decrease the contrast of the image. The mA control is used to determine the current which flows through the filament in the cathode. This changes the number of photons produced, which affects the blackness of the image. Finally, the exposure timer is combined with the mA control to manipulate the darkness of the image. 5. Grids improve the image sharpness when a relatively thick body part is being imaged by maximizing the number of primary photons to pass through to the film, and interacting with the secondary photons to decrease the chance of secondary photons hitting the film. 6. CT scans use multiple x-rays or the rotation of a single x-ray rather than a single straight-forward x-ray to create the final image. The rotational motion of the scanner makes the target area...

Words: 362 - Pages: 2

Premium Essay

Reflection

...the picture and helps me make the story flow. What have you learned about structuring and developing a visual interpretation of a piece of writing? It’s easier to visualise what is happening and make it easier for the audience to interpret what I am trying to say through my words, song and pictures Why did you select the piece of music that you did? I selected a piano cover; I believed that the best song to help my story flow was to include a piano cover sound track. Explain how the overall impact of your piece has been affected/ enhanced by the images, music and narration? The photos involved in the photo story were a mixture of black and white photos and coloured pictures, the black and white pictures I used to make it back my message of it being something bad and the coloured ones are use to represent the things that were happening at the time. What do you believe you will need to do to ensure that the impact of the images, music and narration are conveyed in a piece of imaginative or personal reflective writing? To make sure they all are combined to make the perfect dish and also involve the right music, photos and speech to keep my story on...

Words: 306 - Pages: 2

Free Essay

Photo Editors Adverse Usage

...problem under discussion. * Photo Editors Photo Editors are those software that are used to manipulate, enhance, and transform images on a computer. With the advancement in technology, now a huge number of photo editors are available online i.e. there is no need to download photo editing software. There are hundreds of such software available and they all provide almost same functionality. Some basic features of such software are crop, resize, merge, and liquefy, adding texture, changing color and so on. * Adverse Use of Photo Editors * Photo editing can be used to destroy company’s reputation. Edited pictures, with fake results/effects of the product can be used to displease their consumers. * Edited pictures such as attaching someone’s face to someone else’s body can be used to give threats. The victim can be forced that way to provide money to the editor or obey his orders. * Companies can use it for fraud. They might show fake pictures to the customers and convince them to use their products. * Sometimes people use editors to display fake story. That story might get viral over the internet and bring fame/satisfaction to the person who created it. * Photo editors can be used to easily remove the water mark from pictures, documents etc. and steal someone’s work. * Effects of Edited Images on Society * Such images change the mind set of people. Extreme use of editing in fashion industry to show models slim and flawless is making......

Words: 849 - Pages: 4

Free Essay

Econmics

...enterprise • Eliminate workflow challenges and  decrease report turnaround time in cardiology department • Consolidate cardiology and radiol ogy PACS into one archive for easy image access via their EMR SUCCESS WITH MERGE • Customizable real-time worklists  have improved results delivery and speed to treatment • Went from up to six days to one  day for report-turnaround time with cardiology digital reporting • Consolidated silos and centralized  storage so cardiology and radiology images could be accessed via their EMR and reliably stored in one location Since 2003, St. Mary’s, who performs about 100,000 imaging procedures per year, has selected five Merge solutions to help them address workflow challenges, improve report turnaround time, speed critical results delivery, and better execute image storage and management. “We believe that working with Merge for all of our enterprise imaging and interoperability needs helps St. Mary’s be a better provider. We have one number to call for any question, any issue. That simplifies my busy days and to be honest, I look at Merge as our partner…we’re in this together and they haven’t let me down yet,” said Brian Duncan, Manager of Radiology Services and PACS Administrator at St. Mary’s. Faster Results and Easy Image Access St. Mary’s originally installed Merge PACS to...

Words: 1416 - Pages: 6

Free Essay

Faith or Materials

...Faith or Materials I chose to analyze the first image because it related to my thoughts and beliefs as a Christian. I found this image to be quite interesting; being so it is not like any other ordinary image, it is an image with a hidden message. In any picture, things lie intently in front of and behind one another. It's a basic, pretty well unavoidable pictorial device. It may be a matter of shape over shape, texture against texture. The near thing may appear to be interacting with the far thing -touching it, hitting it, being bisected or overwhelmed by it. There may be something more puzzling going on. In this case, the first image, which caught my eye, was the woman holding the balance. Balance, pearls, and the judgment all in one photo, there must be a purpose to this image. There is a delicate transition between areas of light and shade created by the color relations from the scene. The woman’s blue jacket is so loud on the table compared to all the other materials with such mellow yellow and orange toned colors. The young woman’s concentrated expression and the geometry of the composition, alternates in such a way, the horizontal and vertical lines created by the light entering from the window are all elements which contribute to the creativity of this painting. The young woman is portrayed standing quietly in front of a mirror. On the wall behind her hangs a picture of the Last Judgment, which signifies the spiritual side and the judgment of Christ. The table......

Words: 1146 - Pages: 5

Free Essay

The Last Supper

...The Last Supper As a child whenever I would visit my grandfather’s house there would always be a picture of The Last Supper. In fact he had two, one was in the dining room and the other was hung in the family room. He considered himself a very religious man and believed every family should have one because it symbolized faith and unity within the family. Up until recently I believe the painting was an recreated image of Jesus and his disciples of what the painter felt they should look like and not actual members of the Da Vinci family posing for a photo. Some images shows Jesus with his head bowed slightly while his eyes appear to be close as if he’s blessing the food. Growing up as a child it was taught that everyone sat and ate dinner at the same time and my father gave grace. Even as an adult, whenever I attend family gatherings whether it’s cook-outs, family reunion, birthday parties or dinner at home we all sit to a table and someone blesses the food. I believe that giving thanks or grace as some call it is a simple act of appreciation to God for being the source of all we have, including our food. This is a tradition I follow as a Christian because it was instill in me when I was young and I’m instilling it in my children. The significance of coming together at mealtime shows a sense of unity within the family, every one being of one accord. I believe civilization was created around the dinner table even the Pilgrims and Indians put aside their difference for a......

Words: 281 - Pages: 2

Premium Essay

Thesis Statement On Photography In The Philippines

...The input interactions are creative directors or art directors toiling on particular publicity electioneers. Event photography proposes chances to photographers who relish sprouting images of populaces. The main marketplaces are weddings, anniversaries, graduations, celebrations and business proceedings such as symposiums or award ceremonies. The contacts for this kind of toil may be the specialties themselves or event organizers, such as conference coordinators, hotel managers or wedding planners. Sports photographers shoot live action at games and vend their images to newspaper and magazine publishers, or to the social establishment compering the games. Sports photographers may work on obligation from a sports editor on a separable publication, or they may find an event and proffer the images to an amount of publications. The main contacts are sports editors or art directors at newspapers and magazines, or marketing and municipal dealings managers of sports clubs. The word "photography" was coined from the Greek pedigrees “phōtos”, genitive of “phōs”, "light", and “graphé”, which is "representation by means of lines" or "drawing", mutually meaning "drawing with...

Words: 1176 - Pages: 5

Premium Essay

Portrait Photography Research Paper

... The creative art of portrait photography By RobertDeleon Apr 24, 2014 Like all other branches of photography, Portrait Photography is also a popular term in the world of camera. In fact, many people interested in this area of photography because of the creativity involved in it. The main factor that you need to possess to become a good portrait photographer is your interest. You can make excellent portrait photographs if you have interests in this field irrespective of your experience or training in this field. With the advancements in digital photography, it is easy for people to take better portrait photographs without much knowledge in this area. A lot of people in Virginia approached photographers for portrait photographs. Benefit of digital photography There was a time photographers spend a lot of time and money for taking a single portrait photographs in addition to several tough steps. Today with the advancement in digital photography, the scenario has changed and more and more people become interested in this area of photography. It is not much difficult today to take portrait photographs with the help of digital photography. If you are a skilled photographer Virginia, you can take amazing portrait photographs with the help of a digital camera without too much effort. You can find plenty of great photographers in Virginia who are making amazing portrait photographs. Influence of technology Portrait photography Virginia has been there for a long time but it was......

Words: 543 - Pages: 3

Premium Essay

Profile Paper

...eCreative Images Click, Click. Oh No I’ve been shot at! Wait, that’s just Kristen sneaking around the corner with her camera snapping pictures some candid pictures again. What is Photography? Photography is the art, science and practice of creating durable images. Or as Ken Rockwell put it “Call it vision, imagination, or seeing; it all comes down to the same thing: the ability to envision a final result in your mind's eye, and then to make it so with your tools at hand.” My friend Kristen Savonell-Zehner has taken her hobby/interest to the next level, paid professional. Kristen got her first camera at a very young age and was constantly taking rolls upon rolls of pictures featuring anything and everything she saw. Taking Photography classes in High School helped understand the basics. After high school Kristen went onto college for Radiography, not photography. Over the years there would be the pictures here and there of inanimate objects. Until one day a friend saw a picture of a pumpkin she took and asked if she would mind taking pictures of her and her boyfriend. This was a scary thought as all she had never taken pictures of humans. She continued being a hobbyist photographer for about 10 years, while still being employed as a fulltime Radiography Tech at Boone County Hospital. During her pregnancy she decided she would start charging a nominal fee for her work. Then she got her “big” break, the opportunity to go part time at the hospital and start her “official”......

Words: 726 - Pages: 3

Free Essay

Virtual Imaging

...the capability of zooming smoothly and in more detailed with its high-resolution digital photographs. Regardless of the size and amount of image data, end users can navigate through an image smoothly by using Sea Dragon. On the other hand, Photosynth is a technology that takes a wide variety of images and fusing the images according to similarities to generate three-dimensional models. What I was looking at on the screen in the beginning of the clip are the collective of images on Sea Dragon and its feature of being able to access photos and data either remotely or locally interactive with numerous amount of images. The only way to limit the performance system is depending on the number of pixels on the screen of every end user. Blaise Aguera y Arcas, speaker for Photosynth demo, continues to introduce a project called Photosynth that connects two different technologies, Sea Dragon and computer vision research by a graduate student of University of Washington. An example model of Notre Dame Cathedral is shown, which each of the images that appear in the “orange cones” was taken from Flickr, and is combined together to create the three-dimensional whole image of the Notre Dame Cathedral. Photosynth along with Sea Dragon have been “Jaw Dropping” for the audience and users as it has the capability to navigate smoothly through a bundle of images representing the object. In other words, it is amazing...

Words: 582 - Pages: 3

Free Essay

Ways of Seeing by John Berger

...(Lucy Boylston). I was intrigued by the historical background of the Boylston Family and the timeline (1766 – 1767) during which John Singleton Copley painted six portraits of the Boylston family. It reminded me of a line in John Berger’s essay: “They are declared art when their line of descent can be certified” (150). I wonder how many wonderful and beautiful paintings were just thrown away because they were not of someone important, rich, or famous. There was also information about the cleaning of the painting. I was able to see the difference in the 1921 unclean portrait and the 1950 clean portrait. First, I just saw a nice painting of a woman, but now I can see and appreciate the portrait of Mrs. Timothy Rogers. “The meaning of an image is changed according to what one sees immediately beside it or what comes immediately after it” (156). How very true. After the electrical room, I continued to walk around and found myself paying much more attention to details. Each picture frame is a piece of art in itself! All these intricate details were incredible. “We only see what we look at. To look is an act of choice” (141). Picture 1: The electrical room in the...

Words: 1383 - Pages: 6