Assignments Week 4

Due Date: September 23rd

• Logo History 2nd Draft due today in the Drop box on Blackboard
• Visual Quote Project 3 Sketches- is due to be submitted next week/ Week Five
• Readings Complete Weekly/First Quiz will be Week 6.

To Do

• Complete your 3 visual quote concepts so that they are ready to be submitted next week for critique during class. Quotes should be submitted into the Blackboard DropBox.

• Do use the photo sites discussed to generate ideas for your quote project

To Read

• We reviewed this PS Print site What’s the Difference Between Raster and Vector during Class discussion but read it carefully again for homework.

• Read the following Sections of the University of Michigan’s Image Guide: Raster. Vs. Vector, Image File Formats, Scanning,

To Write

Please write the answers to these questions.

What is a Resolution?, What is Resizing?, How to Change Resolution? and How to Resize an Image?

Study for Test 1

Vocabulary for Test 1

Analog – The analog information we perceive through our senses is continuous and infinite. It is often said that we live in a digital age. However, the natural world we live in is an analog world. For example, the sounds and music we hear are analog signals of sound waves.

Digital – Computers store and transmit information using digital data. To connect our analog world with computers, analog and digital information must be converted from one form to the other and back again. Unfortunately, the conversion process may sacrifice the exactness of the original information. We will discuss the conversion process—sampling and quantization.

Computers – Computers are built from electronic devices that have only two possible states because they are only stable at one of two voltages. Thus, they operate on a binary system, also called base-2. Regardless of the actual voltages of these two states, we might denote them as off and on or false and true. In computer science, we denote this pair of states numerically as 0 and 1, respectively.

Sampling- The natural scenes you see in the world around you are colored in continuous tones. There is no sharp division between one point of color and the next. Each point blends continuously into the next. The first step of the digitization process is sampling, a process by which you record or sample the color in a natural image at discrete, evenly spaced points.

Sample rate – How frequently an analog medium is sampled during the sampling step is called the sample rate. For example, the sample rate in digital imaging determines the resolution of a digital image, In the sampling step, the sound wave is sampled at a specific rate into discrete samples of amplitude values. The higher the sampling rate, the higher the accuracy in capturing the sound. However, a higher sampling rate will generate more sample points, thus requiring more storage space and processing time. To give you a feel for the sampling rate for digital sound, the sampling rate for CD-quality audio is 44,100 Hz (i.e., 44,100 samples per second).

Binary (Base 2) – Because of the current electronic technology that computer systems are built on, they operate on the binary system, which uses base-2 notation. Only two numerals are available in base-2, denoted as 0 and 1 in the language of computers.

Bit Depth – In the quantization step, the number of discrete levels used to map the samples’ values is called the bit depth. For example, the bit depth of a digital image specifies the number of colors available in the image. The discrete and finite nature of computers restricts the precision with which analog media—natural sights and sounds—can be reproduced in digital form. In converting from analog to digital, we sacrifice exactness.

Byte – In computer systems, data is stored and represented in binary digits, called bits. A bit has two possible values, 0 or 1.

Computer file sizes are reported in bits and bytes. Eight bits make a byte. Digital files— image, sound, and especially video files—can be very large, and the file size is often an important consideration that affects your decisions in the file creation and export steps.

Pixel – The sampling step is to record discrete point samples on an image plane. The point sample is called a picture element, or pixel for short. Each pixel stores the color information of the corresponding position in the image. The position is defined by its horizontal and vertical coordinates in the image. Pixel dimensions refer to the image’s width and height in pixels.

Resolution – In digital imaging, increasing the sampling rate increases the image resolution. With higher resolution, you have more samples (pixels) to represent the same scene and thus you capture more details from the original scene. The pixel dimensions of the captured image are increased, and so is the file size of the digitized image.

Lossy Compression– With lossy compression, some information in the original file will be lost and cannot be recovered. JPEG, a popular image file format for Web images, is an example of lossy compression. MP3, a popular file format for digital audio, is another example of lossy compression

Lossless Compression – Many video codecs are also lossy, although a few use lossless algorithms. For files that you want to keep as the start file for further editing, you should avoid applying lossy compression. The exception is video files, which are normally applied with lossy compression.

Vector – Digital imagery can describe the image graphic mathematically. This type of digital image is called a vector graphic. For example, to describe a line _________, you can use a simple equation. Using equations to represent graphics is more concise than bitmapping. Consider this analogy in the context of getting directions for a trip.

Vector graphics are generally more concise descriptions of digital images than bitmaps are. But the most distinct advantage of vector graphics is that they are resolution independent. Let’s explain what resolution independence means and what characteristic of vector graphics makes them resolution independent.

Vector graphics do not use pixels but equations. The images of vector graphics are produced for output or display by calculating the points, according to the equations that make up the graphics. The coordinate system for the equations is arbitrary. That is, its scale can be set to any level. Vector graphics are resolution independent because they can be scaled to any size and printed on any output device at any resolution, without losing detail or clarity in the picture.

Raster – Digital images described by pixel values are called bitmapped images. The term bitmapping refers to how these bits representing the image are stored in computer memory. Bitmapped images also are called raster graphics. The term rastering refers to the way most video displays translate the images into a series of horizontal lines on the screen.

Bitmapped images commonly are used in image editing applications. Because they are composed of pixels, the image content can be edited pixel by pixel easily. However, their size and appearance depend on their output resolution to the device, for example, dots per inch for a monitor and pixels per inch for a printer. Bitmapped images can appear jagged when they’re scaled up onscreen or printed at a low resolution.

Recognize Bitmap File formats–JPEG, PNG, TIF, BMP, etc. Need to be able to recognize the file.
Recognize Vector File Formats–eps, svg– Need to be able to recognize the file.