{"id":92,"date":"2023-06-11T19:33:39","date_gmt":"2023-06-11T19:33:39","guid":{"rendered":"https:\/\/learnlearn.uk\/edexcel-igcse-computer-science\/?page_id=92"},"modified":"2023-06-11T19:33:39","modified_gmt":"2023-06-11T19:33:39","slug":"grayscale-image-representation","status":"publish","type":"page","link":"https:\/\/learnlearn.uk\/edexcel-igcse-computer-science\/grayscale-image-representation\/","title":{"rendered":"Grayscale Image Representation"},"content":{"rendered":"<p>\n<div class=\"arconix-tabs-horizontal\"><ul class=\"arconix-tabs\"><li data-arconix-icon=\" \" data-arconix-color=\" \" class=\"arconix-tab tab-Starter\"><a class=\"\" href=\"#tab-Starter\">Starter<\/a><\/li>\n<li data-arconix-icon=\" \" data-arconix-color=\" \" class=\"arconix-tab tab-GrayscaleImages\"><a class=\"\" href=\"#tab-GrayscaleImages\">Grayscale Images<\/a><\/li>\n<li data-arconix-icon=\" \" data-arconix-color=\" \" class=\"arconix-tab tab-Activity1\"><a class=\"\" href=\"#tab-Activity1\">Activity 1<\/a><\/li>\n<li data-arconix-icon=\" \" data-arconix-color=\" \" class=\"arconix-tab tab-Activity2\"><a class=\"\" href=\"#tab-Activity2\">Activity 2<\/a><\/li>\n<li data-arconix-icon=\" \" data-arconix-color=\" \" class=\"arconix-tab tab-Plenary\"><a class=\"\" href=\"#tab-Plenary\">Plenary<\/a><\/li><\/ul>\n<div class=\"arconix-panes\"><div class=\"arconix-pane pane-Starter\">\n<h3>Starter<\/h3>\n<p>Practice your binary conversion skills using this great game!<\/p>\n<a href='https:\/\/studio.code.org\/projects\/applab\/iukLbcDnzqgoxuu810unLw' class='arconix-button arconix-button-medium arconix-button-gray'>Code.org binary game<\/a>\n<\/div>\n<div class=\"arconix-pane pane-GrayscaleImages\">\n<h3>Grayscale Images<\/h3>\n<p>The images we have been looking at so far have been very simple, pure black and white images, but when we think of black and white images, we aren&#8217;t usually thinking of just black and white, we are thinking of images that contain lots of grays. These are known as <strong>grayscale<\/strong> images.<\/p>\n<div class=\"arconix-column-one-half\">\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-101\" src=\"https:\/\/learnlearn.uk\/binary\/wp-content\/uploads\/sites\/11\/2017\/01\/tree-pciture-grayscale-280x300.jpg\" alt=\"tree-pciture-grayscale\" width=\"280\" height=\"300\" \/><\/p>\n<p>Here is a grey-scale image of a tree<\/p>\n<\/div>\n<div class=\"arconix-column-one-half\">\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-102\" src=\"https:\/\/learnlearn.uk\/binary\/wp-content\/uploads\/sites\/11\/2017\/01\/bw-image-tree-280x300.jpg\" alt=\"bw-image-tree\" width=\"280\" height=\"300\" \/><\/p>\n<p>Here is the same grey-scale image, converted to pure black and white.<\/p>\n<\/div>\n<h3><strong>How do grayscale images work?<\/strong><\/h3>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-103\" src=\"https:\/\/learnlearn.uk\/binary\/wp-content\/uploads\/sites\/11\/2017\/01\/Gray_scale-300x225.jpg\" alt=\"gray_scale\" width=\"300\" height=\"225\" \/><\/p>\n<p>White (255) \u00a0 \u00a0 &#8212;&gt; \u00a0 \u00a0 Black (0)<\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Gray_scale.jpg\">Source : Wikipedia<\/a><\/p>\n<p>With pure black and white images converting them to binary is easy, we just use either a 1 or a 0, but greyscale images are more complicated.<\/p>\n<p>Gray-scale images use a number between 0 (black) and 255(white) for each pixel. This means that instead of just using one bit (0) for each pixel, we have to use 8 bits (e.g. 10100010) instead.<\/p>\n<p>This means that grayscale images are 8 times larger than pure black and white.<\/p>\n<ul>\n<li><span style=\"color: #000080;\">Black and white 8 by 8 \u00a0image \u00a0= \u00a08 x 8 = 64 bits<\/span><\/li>\n<li><span style=\"color: #000080;\">Grayscale 8 by 8 image = \u00a08 x 8 x 8 = 512 bits<\/span><\/li>\n<\/ul>\n<h2>Grayscale image example<\/h2>\n<p>Here is an example of a tiny image, with only 4 pixels. We have enlarged the image, because normally you wouldn&#8217;t be able to see an image this small!<\/p>\n<p>It is made of a four shades of greyscale &#8211; black, dark grey, light grey and white.<\/p>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-full wp-image-105\" src=\"https:\/\/learnlearn.uk\/binary\/wp-content\/uploads\/sites\/11\/2017\/01\/grayscale-image-example-fixed.png\" alt=\"grayscale-image-example-fixed\" width=\"877\" height=\"378\" \/><\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<div class=\"arconix-pane pane-Activity1\">\n<div class=\"arconix-column-two-thirds\">\n<h3>Activity 1<\/h3>\n<p>Click on the spreadsheet below and when it opens up, <span style=\"color: #ff0000;\"><strong>make a copy<\/strong> <\/span>(otherwise you won&#8217;t be able to edit it!) and then create your own image by placing a number from 0 to 255 in the cells.<\/p>\n<a href='https:\/\/docs.google.com\/spreadsheets\/d\/1VGwho-WxMO_XCKZiNMMcFhw8uTA0supeUv1MfOKiApc\/edit?usp=sharing' class='arconix-button arconix-button-medium arconix-button-gray'>Grayscale Image Sheet<\/a>\n<\/div>\n<div class=\"arconix-column-one-third\">\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-216\" src=\"https:\/\/learnlearn.uk\/binary\/wp-content\/uploads\/sites\/11\/2017\/03\/grayscale-make-your-own-picture-300x254.png\" alt=\"grayscale make your own picture\" width=\"300\" height=\"254\" \/><\/p>\n<\/div>\n<\/div>\n<div class=\"arconix-pane pane-Activity2\">\n<h3>Activity 2<\/h3>\n<p>Open up your Google Sheets learning log and fill out the log for today&#8217;s lesson.<\/p>\n<\/div>\n<div class=\"arconix-pane pane-Plenary\">\n<h3>Plenary<\/h3>\n<p>Have a go at this class Kahoot Plenary<\/p>\n<a href='https:\/\/play.kahoot.it\/#\/k\/cf4a5512-a6bc-4aee-8184-b6808f1c7ff5' class='arconix-button arconix-button-medium arconix-button-gray' target=\"_blank\" >Kahoot Plenary<\/a>\n<\/div><\/div><\/div>\n<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"off","neve_meta_content_width":100,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":""},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v20.6 - 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