Using Digitizer 1.12

In this tutorial we review some of the details of using the Digitizer program. The purpose of Digitizer is to digitize a graph or image with an xy-coordinate system. The parts of Digitizer are

1. Entering an image
2. Making the coordinate system
3. Entering points on the image
4. Showing data and exporting data
5. An EXCEL trick - parsing data.

The program itself looks like the diagram below.

Entering an image

There are two ways to enter data. The first and easiest is to type the file name into the program. The first is the simplest.

Method 1. Type into the image input box the complete path name of the image file name. Then choose Load File. In the example above, we have entered the file "circle.jpg."

Method 2. With your browser find the file and be certain that is given by a URL. Copy the complete URL into the image input box and choose Load File.

You can modify the file in three ways:

• Move picture: Choose the "Move picture" button. Then click on and drag the image where you wish it to be.
• Rotate the image: This feature will rotate the image 90² counterclockwise. Warning: You may need to use the Move picture option after rotating to reposition the image.
• Scale to: By inserting any positive number and choosing the scale to button the image will be resized to what every percentage is entered. The aspect ratio of the image is retained. Therefore you will be able to load both very small and very large images and work with them.

Reguirments: The file must be a jpg or a swf file.

Making the coordinate system

There are three steps to making the coordinate system.

1. Choose the "Select origin" button and drag the origin to where you wish it to be and release the mouse button. You can always reselect the "Select origin" if you want to change its position.
2. Choose the "Select point on x-axis button" and drag it to the horizontal position to set your scale. In the box next to it select what value on the x-axis this point should have. The default value is one. Don't worry about the vertical positioning of this point as it will not affect the result. You must choose this value. Otherwise there is no defined scale for a coordinate system.
3. Choose the "Select point on y-axis button" and drag it to the vertical position to set your scale. In the box next to it select what value on the y-axis this point should have. The default value is one. Don't worry about the horizontal positioning of this point as it will not affect the result.    NOTE:If you do not choose a point on the y-axis the same distance as for the x-axis is used.

Entering points on the image

The is the only tricky part. Choose the "Select points" button. Position the cursor near where you wish to digitize a position on the image. Then depress and hold the left mouse button while you drag the point into place. You will not see the point until you begin to drag it.

This is important. Each point requires a few pixels of dragging to become active. This allows you precision positioning of your data.

In general, all points are accurate to within 2% of their positioning. A limit of 50 points can be entered.

Options available to you include clearing all points and removing the most recent point drawn, according to the self-evident buttons.

Showing data and exporting data

After you have created your points, you can display them by choosing the "Show points" button, which is the same button used for choosing to select points. The newly digitized points are display in the box as shown above. This set of points can be copied and pasted into your spreadsheet of word processor for further calculations and other work.

If you have missed point that you wish to digitize you can then choose "Add more points" and continue building your data. The show points and the new data will be appended to the old data.

Toggling spaces or commas. You may also choose to display the data with only a space between coordinate pairs. Do this by selecting the "Spaces between" button. Selecting the button again will switch back to the commas between mode.

	Left: Set for commas between
	Right: Set for spaces between

An EXCEL trick

When you paste this data into EXCEL it will display in just one column of the spreadsheet. This makes calculations impossible. However it is possible to parse the data in the following way. Suppose the data from the Digitizer is pasted into EXCEL as shown below.

 

This data can be parse into two columns by the following trick. Highlight the data. In EXCEL choose the Data+Text to Column option. You will obtain the following menu. Be sure the "Delimited" button is selected. Click next

Now select Finish. The data will be parsed into two columns as shown below, and ready for calculations.

Technical

Digitizer 1.12 is a complete Internet based digitizing software that should run on any browser with the Flash 6 Player. The features of the software will allow any JPEG image or SWF movie to be loaded, a coordinate system (i.e.origin) defined, points on the x-axis and y-axis specified, and points selected.
(URL: http://www.macromedia.com/software/flashplayer/)