{"id":168311,"date":"2010-05-06T17:18:59","date_gmt":"2010-05-07T00:18:59","guid":{"rendered":"http:\/\/www.esri.com\/arcgis-blog\/?post_type=blog&p=168311"},"modified":"2018-12-18T11:08:02","modified_gmt":"2018-12-18T19:08:02","slug":"calculating-an-area-in-raster","status":"publish","type":"blog","link":"https:\/\/www.esri.com\/arcgis-blog\/products\/arcgis-desktop\/imagery\/calculating-an-area-in-raster","title":{"rendered":"Calculating an area in raster"},"author":4331,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"_acf_changed":false,"_searchwp_excluded":""},"categories":[22931,22941],"tags":[28271,25041,38411,23011],"industry":[],"product":[37031,36991],"class_list":["post-168311","blog","type-blog","status-publish","format-standard","hentry","category-imagery","category-mapping","tag-image-classification","tag-landsat","tag-mapping-center","tag-raster","product-spatial-analyst","product-arcgis-desktop"],"acf":{"short_description":"I have a tile from Landsat imagery. I displayed in Envi bands of my interest and received a RGB raster. I uploaded my raster image to ArcMap","flexible_content":[{"acf_fc_layout":"content","content":"

Question:<\/strong>\u00a0I have a tile from Landsat imagery. I displayed in Envi bands of my interest and received a RGB raster. I uploaded my raster image to ArcMap and now I am looking for the way to calculate an area displayed in a particular color: in my case in blue. I tried reclassifying, but this did not solve my problem. Could you, please suggest any solution?<\/p>\n

Answer:\u00a0<\/strong>Without classifying the image, you can do this by selecting cells from a single band. In ArcMap, click the Add Data button, navigate to the location of the RGB raster, and then double click the name of the raster to see the individual bands. Note that although you want to select the cells that have a blue color in the composite RGB raster, you might find that the red or green bands actually display the area in blue with a more uniform gray tone. So try adding all three individual bands and seeing which one shows the blue area in a more uniform gray tone.<\/p>\n

On the raster that has the most uniform gray tone for the blue area, use the Identify tool on the Tools toolbar to see what the pixel values of the area that is blue in the composite image are. Once you have the pixel value or range of values, use the\u00a0Con<\/a>\u00a0tool\u00a0to perform a conditional evaluation on the one raster band.<\/p>\n