Key Features of a Digital Image

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by Teacher MAS0 views·Updated Aug 21, 2020
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  1. Hello, my dear students, How are you today?
  2. I hope that you're all doing great.
  3. We have started in the previous lesson talking about digital
  4. images. Add as I said, This is one off the
  5. key concepts that you have to understand before we start
  6. with the image editing course.
  7. Today we will continue talking about the key features off
  8. a digital image.
  9. But before we begin, let's remember what we covered in
  10. the previous lesson.
  11. If you remember, we said that the digital image is
  12. composed off discreet pixels on.
  13. We said the pixel is the smallest element, that how
  14. that each digital image has ah, nde.
  15. The digital images there are represented digitally in a binary
  16. code. Do you still remember what a Byner could is
  17. if you remember, we said the boy in record is
  18. the computer language.
  19. That is how the computer is storing the digital images
  20. inside it by using zeros.
  21. And once this is mainly what we started with in
  22. the previous listen at, you have to keep these things
  23. in mind when we are waking with digital images.
  24. So let's see what we are going to cover today.
  25. Our main objectives for today is to identify the key
  26. features off a digital image, and we will understand to
  27. new terms lossy and lost lis image file compression.
  28. Let's begin.
  29. Before we begin with these two terms, we have to
  30. understand what is a file compression.
  31. This is a concept related to all data stored inside
  32. the computer.
  33. Sometimes we need to compress the doubt off any file
  34. time. This is not only related to images, this could
  35. be any file stored inside the computer.
  36. You need to compress that.
  37. Sometimes. Why do we need to compress it so it
  38. will take less space?
  39. Actually, compression is according process.
  40. So the main benefit off the compression and the main
  41. use is to reduce the size off the fire.
  42. Sometimes, if I need to send a specific file, that
  43. is, that has a large size.
  44. I want to send it by email in that say
  45. to someone I cannot attach it to my e main
  46. because it has a large size.
  47. So what can I do?
  48. I have to compress the fight.
  49. So by compressing yet it will take less space.
  50. The size will decrease.
  51. So then I can attach this fight.
  52. Why do you think also.
  53. I may need to compress them some files.
  54. Sometimes you may need toe applaud it too.
  55. Any place to e m a cloud?
  56. I cloud one drive Whatever.
  57. Sometimes when needed toe upload it.
  58. It takes a long time if you are applauding a
  59. large size off a file So what can I do?
  60. In this case, I can't compress the file.
  61. Why do I need to compress it To reduce its
  62. size. So, actually, how Compression works inside the computer.
  63. You have to use this software that enables you to
  64. compress this file.
  65. This is called a compressor or the encoder.
  66. It makes a special code by compressing this file so
  67. the file will be compressed or encoded with the new
  68. code that is applied to it.
  69. Then you can send it.
  70. Let's say I'm going to send defying.
  71. I'll use this software that will compress that large file
  72. size and the other side.
  73. If I want to open that compressed foreign, I need
  74. a D compressor or a dick order that would return
  75. it back to its original data so I can use
  76. it then.
  77. Okay, I have a question for you.
  78. Can you give me a name off a software that
  79. is used for five compression.
  80. There is a program that you are all familiar with
  81. at I'm sure that you have used it before.
  82. It is the one WinZip.
  83. The winds up is a software, A program that is
  84. used as a compressor.
  85. As an included, it would compress this file to reduce
  86. its size on.
  87. Then when you wanna open it again, you have to
  88. decompress it by using the same program, so it will
  89. return it back to the original data.
  90. So basically, you have to understand.
  91. What is that?
  92. A compression?
  93. Again? It is according process.
  94. So that data will take less space.
  95. This is the main use off that a compression on.
  96. Why do we use it?
  97. Okay, so when we talk about images, we have to
  98. talk about image five compression.
  99. We have basically with image file compression, two types off
  100. data compression related to image for compression.
  101. We call them lossy and lossless.
  102. What is the difference between each type off these file
  103. compressions. So let's begin with the first type, which is
  104. lossy file compression with the los e file compression.
  105. It is a way off compressing images, boy discord ing
  106. the unnecessary data.
  107. So how this file compression works, It looks internally inside
  108. the daughter that this image has and it's towards discord
  109. ing the unnecessary data inside that fire.
  110. But if you take a look at the los e
  111. file compression that we have on the right side of
  112. the image, you can see that it's not a very
  113. clear image.
  114. It has a no resolution.
  115. Why? Because we used the lossy file compression.
  116. This is one off or the main, this advantage off
  117. using lossy foil compression.
  118. And actually, we use this type of compression when we
  119. don't care about the resolution off the image.
  120. So no, see, file compression well result with a low
  121. resolution off the image.
  122. So you just use this type of compression if you
  123. you don't need a high resolution.
  124. If the absolute resolution is not required for this image,
  125. so again, lossy file compression, it is.
  126. It works.
  127. Why discarding the unnecessary data and it results, introducing the
  128. image, size and resolution.
  129. So that's why it's not preferred to use this type
  130. of compression if we care about the resolution.
  131. If we need a high quality image, okay?
  132. So this is lossy.
  133. What about last lists?
  134. Lost list?
  135. It works with a different way.
  136. Actually it works, boy, or it compresses the image by
  137. recording pattern data.
  138. What do we mean by this?
  139. If I have an image that has 200 red points
  140. so instead off considering these red points inside the computer
  141. as Redpoint Redpoint Redpoint, 20 100 times, it will just
  142. compress it as 20 100 red points.
  143. This is the concept off recording pattern that it will
  144. find the pattern that we have inside the image.
  145. Ah, nde.
  146. It will start recording these patterns toe save the space
  147. or to reduce the space off the image.
  148. This kind of compression, it doesn't lead to the loss
  149. off any original pixels when d compressing the file.
  150. So that's why it has a high resolution.
  151. So if you take a look at these two pictures,
  152. you can see that the lost lists a file compression
  153. has a better resolution than the law.
  154. See one.
  155. So it keeps the pictures with the high quality.
  156. So when it is d compressed, it will be reconstructed.
  157. It will reconstruct the data exactly as the original image
  158. with no loss in the origin and data.
  159. That's why this type off file compression is used for
  160. medical X ray images.
  161. They use lossless because they care about the resolution and
  162. they need a high quality pictures.
  163. So with the lossless file compression it works.
  164. Boy recording the pattern data.
  165. That's why it keeps the high resolution and a good
  166. quality off the images.
  167. While with Los E, it reduces the unnecessary data.
  168. It discards the unnecessary data.
  169. That's why when we decompress this file, it has low
  170. quality with low resolution.
  171. These are the two main types off image file compression.
  172. So I gave you one practical example for using lossless
  173. image file compression, which is for the medical X ray
  174. images. Can you find any practical example for the los
  175. E file compression appointing for your answers on?
  176. Of course, you have to solve the worksheet that I
  177. have sent to you.
  178. I hope that you understand the terms that we have
  179. covered today.
  180. And if you have any questions, please send it to
  181. me. Have a wonderful day