Help on Vectorizing Pictures

How can one compare his results with other works from a paper or book. Typing them in by hand is neither much fun nor very accurate. The following program may help you with it.

Image Location:

Specify either an URL starting with the substring "http://" or a local filename. Filenames can only be loaded, when the security restrictions of your browser are turned off.

Load

The applet will try to load the specified image. If you load it from the internet, please be patient. Due to synchronizing problems, sometimes the image size can not be set. In this case please reload the image.

Canvas:

Thats where the image should appear after loading. If you have some graphs digitized, their points will be shown, too. Your image may not fit in the canvas as a total. Use the sliders to adjust the image.

Mouse:

One of several events can be selected for the canvas:

Pick Points

Pick points by hand. This can be used, when the vectorizing algorithm will not work, or to select further points. Any time this choice is selected a new curve will be started.

Vectorize

Move the mouse pointer over a graph on the image and press the button. The algorithm will try to trace the graph. Any point can only be vectorized once.

Delete Points

Drag a rectangle over the points that should be deleted.

Delete Graph

Select a graph that should be deleted. Once you deleted the graph, you can't vectorize it again.

Reference1/2

For scaling the digitized points two reference points are needed. By default these points lie in the upper left and lower right corner and the size is set to the imagesize.

Pick

To specify the reference points set the mouse event to pick and select the points in the image.

Vectorizing Epsilon:

This value is used inside the algorithm to remove points that can be represented by a single line. Default is 0.7.

Marker Size:

This value specifies the size of the point markers shown on the image.

Vectorize All

This will find all graphs in the image.

Reset

Deletes all points and resets the image. Resetting of the image is necessary before trying to vectorize deleted graphs.

Print Points

Print the x and y coordinate values in the output log. Different graphs will be separated by an ampersand '&'

Clear Output

Clears the output log.

Help

Short info on the algorithm.

The point information can be printed here. To work with the point data, select all the content in this window and copy it into any texteditor. Points are best worked up with the PD-program xvgr/xmgr by Peter Turner.

The algorithm was written by Jens Trapp. Some ideas concerning the tracking of pixels are from an algorithm by David Cook. Any kind of feedback is appreciated. Have fun with the Vectorize Program ...