{"id":1152,"date":"2010-01-14T15:58:49","date_gmt":"2010-01-14T21:58:49","guid":{"rendered":"http:\/\/bililite.nfshost.com\/blog\/?p=1152"},"modified":"2012-04-25T16:09:12","modified_gmt":"2012-04-25T22:09:12","slug":"engauge-digitizer-tutorial","status":"publish","type":"post","link":"https:\/\/bililite.com\/blog\/2010\/01\/14\/engauge-digitizer-tutorial\/","title":{"rendered":"Engauge Digitizer Tutorial"},"content":{"rendered":"

A simple walkthrough to use the Engauge Digitizer<\/a> to pull values off a \"printed\" graph<\/h3>\r\n

There's a far more complete manual that comes with the download, but these are the steps I used to generate the data for the\r\nwebservices<\/a> graphs. It assumes you've got a black and white image of the graph, with continuous lines for the\r\ndata and orthogonal gridlines, and linear axes.<\/p>\r\n

We'll use the bilirubin risk levels from the AAP bilirubin guidelines<\/a>:<\/p>\r\n<\/a>\r\n

    \r\n

  1. Open the digitizer<\/h4>\r\n

    You can't use Open with...<\/code> from the context menu because the program expects filenames as part of the options;\r\nyou can read the manual to see how to modify the context menu. Click Import<\/code>\r\non the toolbar: \"Import and select your image file:<\/p>\r\n\"graph<\/a>\r\n

    Save your work (it's a .dig<\/code> file) often. You don't need me to remind you.<\/p>\r\n<\/li>\r\n

  2. Set the axes<\/h4>\r\n

    Click Axis Point<\/code> in the toolbar: \"Axis and click on the origin\r\n(lower left corner) of the graph and enter the x,y values for the origin in the units of the graph (not pixels!). Usually that's (0,0)\r\nbut can be anything. Click on the maximum of the y-axis (upper left corner), then the maximum of the x-axis (lower right corner).<\/p>\r\n

  3. Remove the grid<\/h4>\r\n

    Select Grid Removal...<\/code> from the Settings<\/code> menu. Select \"Remove thin lines parallel to the axes\" and play with\r\nthe \"Minimum line thickness\" until the gridlines are gone from the preview on the bottom but the real curves are still there.<\/p>\r\n\"remove<\/a>\r\n

    Now the grid is gone and digitizing the curves will be easy:<\/p>\r\n\"graph<\/a>\r\n<\/li>\r\n

  4. Create curves<\/h4>\r\n

    Select Curves...<\/code> from the Settings<\/code> menu. Create as many curves as you need (we have three). Give them descriptive\r\nnames if you like:<\/p>\r\n\"curve<\/a>\r\n<\/li>\r\n

  5. Digitize each curve<\/h4>\r\n

    Click Segment Fill<\/code> in the toolbar: \"Segment. For each curve, select it\r\nfrom the curve menu: \"Axis and click the points on the graph for that curve until\r\nit is covered with points. There's no undo command. If a wrong point is included, use the Select<\/code> tool:\r\n\"Select to select the bad points and use the Delete<\/code> key. To add individual points,\r\nuse the Curve Point<\/code> tool: \"Curve. In a few clicks, you have the fully\r\ndigitized graph:<\/p>\r\n\"curve<\/a>\r\n<\/li>\r\n

  6. Set up the export<\/h4>\r\n

    If you exported the data now, you'd have lots of points; probably far more than is justified from the original graph. Decide which x-axis\r\nvalues should be exported (the program will interpolate appropriately if the digitized points don't land exactly). Select\r\nGrid Display...<\/code> from the Settings<\/code> menu:<\/p>\r\n\"grid<\/a>\r\n

    The values to be specified are related by count = (stop - start)\/step<\/code> so you only need to specify three; select the one you\r\ndon't<\/em> want to specify from the Disable<\/code> dropdown menu. Make sure that the start and stop values are actually in the curve;\r\nthe program will happily extrapolate off the curve but it's probably not scientifically legitimate. Ignore the y axis grid lines.<\/p>\r\n

    Select Export Setup...<\/code> from the Settings<\/code> menu. In the Points Selection<\/code> section, select\r\nIntepolate Y's at gridline X's<\/code>.<\/p>\r\n\"grid<\/a>\r\n<\/li>\r\n

  7. Export<\/h4>\r\n

    Click the Export<\/code> icon in the toolbar: \"Export. Pick a name and you now have a\r\nCSV<\/a> file with your data. Simple, no?<\/p>\r\n<\/li>\r\n<\/ol>","protected":false},"excerpt":{"rendered":"A simple walkthrough to use the Engauge Digitizer to pull values off a \"printed\" graph There's a far more complete manual that comes with the download, but these are the steps I used to generate the data for the webservices graphs. It assumes you've got a black and white image of the graph, with continuous […]","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"_links":{"self":[{"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/posts\/1152"}],"collection":[{"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/comments?post=1152"}],"version-history":[{"count":7,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/posts\/1152\/revisions"}],"predecessor-version":[{"id":2302,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/posts\/1152\/revisions\/2302"}],"wp:attachment":[{"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/media?parent=1152"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/categories?post=1152"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bililite.com\/blog\/wp-json\/wp\/v2\/tags?post=1152"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}