{"id":179281,"date":"2012-08-08T23:40:44","date_gmt":"2012-08-08T23:40:44","guid":{"rendered":"http:\/\/www.esri.com\/arcgis-blog\/?post_type=blog&#038;p=179281"},"modified":"2018-12-18T11:04:53","modified_gmt":"2018-12-18T19:04:53","slug":"apparent-reflectance-raster-function","status":"publish","type":"blog","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function","title":{"rendered":"Apparent Reflectance Raster Function"},"author":4061,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"_acf_changed":false,"_searchwp_excluded":""},"categories":[22931],"tags":[23011,24661],"industry":[],"product":[36991],"class_list":["post-179281","blog","type-blog","status-publish","format-standard","hentry","category-imagery","tag-raster","tag-raster-functions","product-arcgis-desktop"],"acf":{"short_description":"The Apparent Reflectance raster function calibrates image brightness values (DN) for some satellite sensors.","flexible_content":[{"acf_fc_layout":"content","content":"<p><a href=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_after2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-thumbnail wp-image-18911\" src=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_after2-150x150.png\" alt=\"apparent reflectance\" width=\"150\" height=\"150\" \/><\/a>The\u00a0<a title=\"apparent reflectance function\" href=\"http:\/\/resources.arcgis.com\/en\/help\/main\/10.1\/index.html#\/\/009t0000023s000000\" target=\"_blank\" rel=\"noopener\">Apparent Reflectance<\/a>\u00a0raster function calibrates image brightness values (DN) for some satellite sensors. The main advantage of apparent reflectance function is to adjust the images to a theoretically common illumination condition, so there should be less variation between scenes from different dates and from different sensors. This can be useful for image classification, color balancing, and mosaicking.<\/p>\n<p>The function performs two calibrations. The first calibration is to convert the DN value to the top of atmosphere (TOA) radiance based on the sensor properties (i.e. gain\/bias or LMAX\/LMIN). The second calibration is to convert the TOA radiance to apparent reflectance, based on sun elevation and acquisition date. The formulas used in the two conversions can be found in section\u00a0<a title=\"section 11.3 of LS7 Data Handbook\" href=\"http:\/\/landsathandbook.gsfc.nasa.gov\/data_prod\/prog_sect11_3.html\" target=\"_blank\" rel=\"noopener\">11.3.1 and 11.3.2<\/a>\u00a0of the Landsat 7 Science Data User Handbook.<\/p>\n<p>Apparent reflectance is a ratio and its native output range is 0-1. For display purposes, in this function, the ratio is multiplied by 255, and the output is therefore stretched from 0-1 to 0-255. When using default 8-bit unsigned integer output data type, the value is rounded down to integers.<\/p>\n<p>Some scientific research (e.g. serving as input of atmospheric model to achieve surface reflectance) requires the original ratio. This can be achieved by 1) selecting apparent reflectance raster function output type to be 32 Bit float, and 2) adding an arithmetic raster function immediately after this function to divide the value by 255.<\/p>\n<div id=\"attachment_18905\" class=\"wp-caption alignleft\">\n<p><a href=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_before.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-18905 \" src=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_before.png\" alt=\"Before Apparent Reflectance \" width=\"256\" height=\"309\" \/><\/a><\/p>\n<p class=\"wp-caption-text\">Before Apparent Reflectance<\/p>\n<\/div>\n<div id=\"attachment_18907\" class=\"wp-caption alignleft\">\n<p><a href=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_after1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-18907 \" src=\"http:\/\/blogs.esri.com\/esri\/arcgis\/files\/2012\/08\/AppReflect_after1.png\" alt=\"After Apparent Reflectance\" width=\"256\" height=\"309\" \/><\/a><\/p>\n<p class=\"wp-caption-text\">After Apparent Reflectance<\/p>\n<\/div>\n<p>This function can only be used with specific imagery and may be automatically applied when adding data to a mosaic dataset using the appropriate raster type. The applicable sensors are Landsat, IKONOS, and QuickBird. If this function is applied to a dataset that is invalid it will slow the function chain but make no adjustments.<\/p>\n<p>This function modifies the image values, so previous statistics and histograms are no longer valid. This function should be applied early in the function chain, after band extraction (reordering) and prior to any stretching or other radiometric function.<\/p>\n<p><em>Written by: Hua Wei<\/em><\/p>\n"}],"authors":[{"ID":4061,"user_firstname":"Simon","user_lastname":"Woo","nickname":"Simon Woo","user_nicename":"simo3919","display_name":"Simon W","user_email":"swoo@esri.com","user_url":"","user_registered":"2018-03-02 00:15:40","user_description":"Simon is an Esri product engineer on the Raster team. He works mainly with Pixel Editor, raster visualization, georeferencing, and documentation.","user_avatar":"<img alt='' src='https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=96&#038;d=blank&#038;r=g' srcset='https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=192&#038;d=blank&#038;r=g 2x' class='avatar avatar-96 photo' height='96' width='96' loading='lazy' decoding='async'\/>"}],"related_articles":"","card_image":false,"wide_image":false},"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v25.9 (Yoast SEO v25.9) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Apparent Reflectance Raster Function<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Apparent Reflectance Raster Function\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\" \/>\n<meta property=\"og:site_name\" content=\"ArcGIS Blog\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/esrigis\/\" \/>\n<meta property=\"article:modified_time\" content=\"2018-12-18T19:04:53+00:00\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:site\" content=\"@ESRI\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":[\"Article\",\"BlogPosting\"],\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\"},\"author\":{\"name\":\"Simon W\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/6f650fb8cda0894dd6401d333dcdcb64\"},\"headline\":\"Apparent Reflectance Raster Function\",\"datePublished\":\"2012-08-08T23:40:44+00:00\",\"dateModified\":\"2018-12-18T19:04:53+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\"},\"wordCount\":4,\"publisher\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#organization\"},\"keywords\":[\"raster\",\"raster functions\"],\"articleSection\":[\"Imagery &amp; Remote Sensing\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\",\"url\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\",\"name\":\"Apparent Reflectance Raster Function\",\"isPartOf\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#website\"},\"datePublished\":\"2012-08-08T23:40:44+00:00\",\"dateModified\":\"2018-12-18T19:04:53+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.esri.com\/arcgis-blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Apparent Reflectance Raster Function\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#website\",\"url\":\"https:\/\/www.esri.com\/arcgis-blog\/\",\"name\":\"ArcGIS Blog\",\"description\":\"Get insider info from Esri product teams\",\"publisher\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.esri.com\/arcgis-blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#organization\",\"name\":\"Esri\",\"url\":\"https:\/\/www.esri.com\/arcgis-blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/04\/Esri.png\",\"contentUrl\":\"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/04\/Esri.png\",\"width\":400,\"height\":400,\"caption\":\"Esri\"},\"image\":{\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/esrigis\/\",\"https:\/\/x.com\/ESRI\",\"https:\/\/www.linkedin.com\/company\/5311\/\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/6f650fb8cda0894dd6401d333dcdcb64\",\"name\":\"Simon W\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=96&d=blank&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=96&d=blank&r=g\",\"caption\":\"Simon W\"},\"description\":\"Simon is an Esri product engineer on the Raster team. He works mainly with Pixel Editor, raster visualization, georeferencing, and documentation.\",\"url\":\"\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Apparent Reflectance Raster Function","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function","og_locale":"en_US","og_type":"article","og_title":"Apparent Reflectance Raster Function","og_url":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function","og_site_name":"ArcGIS Blog","article_publisher":"https:\/\/www.facebook.com\/esrigis\/","article_modified_time":"2018-12-18T19:04:53+00:00","twitter_card":"summary_large_image","twitter_site":"@ESRI","schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":["Article","BlogPosting"],"@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#article","isPartOf":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function"},"author":{"name":"Simon W","@id":"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/6f650fb8cda0894dd6401d333dcdcb64"},"headline":"Apparent Reflectance Raster Function","datePublished":"2012-08-08T23:40:44+00:00","dateModified":"2018-12-18T19:04:53+00:00","mainEntityOfPage":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function"},"wordCount":4,"publisher":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/#organization"},"keywords":["raster","raster functions"],"articleSection":["Imagery &amp; Remote Sensing"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function","url":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function","name":"Apparent Reflectance Raster Function","isPartOf":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/#website"},"datePublished":"2012-08-08T23:40:44+00:00","dateModified":"2018-12-18T19:04:53+00:00","breadcrumb":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/apparent-reflectance-raster-function#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.esri.com\/arcgis-blog\/"},{"@type":"ListItem","position":2,"name":"Apparent Reflectance Raster Function"}]},{"@type":"WebSite","@id":"https:\/\/www.esri.com\/arcgis-blog\/#website","url":"https:\/\/www.esri.com\/arcgis-blog\/","name":"ArcGIS Blog","description":"Get insider info from Esri product teams","publisher":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.esri.com\/arcgis-blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.esri.com\/arcgis-blog\/#organization","name":"Esri","url":"https:\/\/www.esri.com\/arcgis-blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/04\/Esri.png","contentUrl":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2018\/04\/Esri.png","width":400,"height":400,"caption":"Esri"},"image":{"@id":"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/esrigis\/","https:\/\/x.com\/ESRI","https:\/\/www.linkedin.com\/company\/5311\/"]},{"@type":"Person","@id":"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/6f650fb8cda0894dd6401d333dcdcb64","name":"Simon W","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.esri.com\/arcgis-blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=96&d=blank&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/284f5c139a24b4d63be933eebce2580a4a5dc93d4c09b375bd1d2368019e8748?s=96&d=blank&r=g","caption":"Simon W"},"description":"Simon is an Esri product engineer on the Raster team. He works mainly with Pixel Editor, raster visualization, georeferencing, and documentation.","url":""}]}},"text_date":"August 8, 2012","author_name":"Simon W","author_page":false,"custom_image":"https:\/\/www.esri.com\/arcgis-blog\/app\/uploads\/2025\/08\/Newsroom-Keyart-Wide-1920-x-1080.jpg","primary_product":"ArcMap","tag_data":[{"term_id":23011,"name":"raster","slug":"raster","term_group":0,"term_taxonomy_id":23011,"taxonomy":"post_tag","description":"","parent":0,"count":147,"filter":"raw"},{"term_id":24661,"name":"raster functions","slug":"raster-functions","term_group":0,"term_taxonomy_id":24661,"taxonomy":"post_tag","description":"","parent":0,"count":22,"filter":"raw"}],"category_data":[{"term_id":22931,"name":"Imagery &amp; Remote Sensing","slug":"imagery","term_group":0,"term_taxonomy_id":22931,"taxonomy":"category","description":"","parent":0,"count":770,"filter":"raw"}],"product_data":[{"term_id":36991,"name":"ArcMap","slug":"arcgis-desktop","term_group":0,"term_taxonomy_id":36991,"taxonomy":"product","description":"","parent":36981,"count":325,"filter":"raw"}],"primary_product_link":"https:\/\/www.esri.com\/arcgis-blog\/?s=#&products=arcgis-desktop","_links":{"self":[{"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/blog\/179281","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/blog"}],"about":[{"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/types\/blog"}],"author":[{"embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/users\/4061"}],"replies":[{"embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/comments?post=179281"}],"version-history":[{"count":0,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/blog\/179281\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/media?parent=179281"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/categories?post=179281"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/tags?post=179281"},{"taxonomy":"industry","embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/industry?post=179281"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.esri.com\/arcgis-blog\/wp-json\/wp\/v2\/product?post=179281"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}