3 Answer
To do some research on the factors which affect file size for different types of data.
18 Part 4
So, in the end, standards for both types of data were developed because they were needed for different purposes. For example, professional photographers wanted to take very high-resolution digital photographs. They wanted to be able to enlarge their photographs, that is to make them bigger, without losing quality. They were prepared to pay for the high cost of storage, so they wanted data standards that would give them the high resolutions they needed, so they got TIFF and bitmap data standards. Both TIFF and bitmap files were very large. TIFF files are a high-quality data standard which are often used for scanning documents or high-quality images. On the other hand, amateur photographers were happy with much lower-resolution photographs and didn’t want to pay a lot for storage, so the JPEG data format was very good for them because it reduced the file size a lot. Another example is sound files. Some people want very high-quality sound, so they use larger file types such as WAV files. Others are happier with lower-quality sound (which is still good) and which has smaller file sizes. So, we can make a distinction between two types of
standards which we call lossy and lossless. Lossy standards lose information and have smaller file sizes, lossless standards keep much more of the information and have larger file sizes. The file types I talked about earlier can fit into both of these two categories. For example, BMP files or TIFF files are lossless, that is to say, they keep as much of the information about the original images as possible. The same is true of WAV files which keep as much of the original sound information as possible. Examples of lossy files are MP3 files, where some
of the sound information is removed – or lost, to create a smaller file size and JPEG files where information about an image is lost, providing a lower resolution. This means that the images are not as sharp or clear. When you increase the size of the JPEG image, it looks much more blurry than a high-resolution image. So, the distinction between lossy and lossless data standards is very important for image, sound and video data because they represent a trade-off between quality and size. This is called compression and compression techniques are very important in speeding up the transfer of data and, also, of making it easier to store. In fact, much of the data transfer that we rely on for everyday communication relies on very advanced data compression techniques. So, for this reason, I would like you to do some research on the factors which affect file size for different types of data.
3.2 Listening
2. Elicit ideas, and feed back the answer orally. Set the students to work on the research task in pairs or individually, and explain that they will need to report back in Lesson 3.3.
F
Check that students understand the task. These are sentences about the ideas in the lecture.
19
Set for pairwork. Say or play the sentences. Give time for students to discuss and then respond.
Ask students to justify their answers.
Answers 1. true 2. true 3. false It has 128 characters. 4. true
5. false The first 128 characters were the same as in ASCII.
6. true 19
1. Without data standards, it is not possible to share data between computers.
2.
In a character set, each character is represented as binary code.
3. The first ASCII character set had 256 characters. 4.
In Unicode, each binary number always represents the same characters.
5. Unicode and ASCII do not have anything in common. 6.
JPEG images have lower resolution when they are increased in size.
G
Set for pairwork. Elicit ideas from students, and encourage them to explain and justify them.
Answers Photograph 1 uses a lossless format; photograph 2 uses a lossy format such as JPEG. This can be seen in the larger pixel sizes.
Lossless formats tend to be used by professionals who need very high-quality data to work with. Lossy formats tend to be used where lower-quality images or audio are acceptable. Because lossy formats are smaller in size, they require less storage space and less processing power. This makes it easier to edit the data. In general, however, lossy formats are becoming very sophisticated and the line between the two is becoming more blurred.
56
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259
