Tutorial 6: Convert a Pie Chart to data

This tutorial shows how to convert a pie chart to data. First start the Chart2Data App and select the Pie Chart icon. The tutorial is shown in expert mode (dark blue background). If you start Chart2Data for the first time the app is in Wizard mode by default (dark purple background). You can change the user mode in the App settings. Note: in case you change the user mode during a chart conversion process the new setting will be saved but will not be active since the user mode cannot be changed during a chart conversion process. The new setting will become active once you reach the start page again and choose a chart category.

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Then select the Pie Chart Image to convert by clicking / tapping on the large folder icon. For this tutorial an image from the examples zip-file which can be downloaded from the downloads section is used. The name of the image file used in this tutorial is:

PieChart.jpg

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Now your screen should look like this:

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As first step we have to define the center point of the pie chart. In order to do this highlight the text “Center Point Coordinates” by clicking / tapping on it.

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Now zoom in to the center point of the pie chart where all section borders intersect and select the pixel coordinates by clicking / tapping on the specific pixel.

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The pixel coordinates show up. Now highlight the text “List of Selected Points” by clicking / tapping on it.

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Now move the pointer up to the first section interface and click / tap on the section interface.

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Note: make sure that you really select a pixel close to the edge of the pie chart because the conversion algorithm checks the distances from the center point and allows only a difference of 5%. This is a measure of safety in order to prevent that distorted pie charts are converted, because distorted pie charts do not deliver accurate converted data. A tutorial on how to deal with distorted pie charts will be published soon.

It does not matter with what section interface you start and which sequence you choose to select the interface points, because the conversion algorithm will sort the sections starting with the top one and counting clock wise (see next figure). The author recommends to use that same sequence while selecting the section interfaces in order not to get confused. If needed you can delete an interface point from the list by clicking /tapping on it.

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Now move the pointer to the next section interface and select the pixel accordingly.

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Repeat the process until you have selected all section interfaces. Be careful not to select an interface twice even not the one you started with.

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Now we are all set to start the conversion process by clicking / tapping on the Next button in the upper right corner of the screen.

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After Chart2Data is finished with the conversion, you are prompted for a result filename.

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When the data are written to the file the result screen will show up.

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That is it!