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Canny Edge Detector Experimentation

HIPR Applet Running Instructions

The following are instructions on how to run the applets which are part of the HIPR package. These applets are designed to allow the user to try out the operators which are outlined in the worksheets.

You may want to review the general instructions first, which gives a demonstration overview, JAVA details, browser details, known bugs, etc.

Source for this operator.

Image Loading

You can experiment with different images using any of the images supplied in HIPR or by a URL. Some of those available in HIPR have the prefixes given here and .gif as the file extension: grayscale (cam1, che1, cln1, fru1, man8, str1, str2, str3, tol1, txt2, wal2, wom1, wom2, urb1, xra1) and range (bae1, fac1, phn2, ren1, ren2, ufo1, ufo2, ufo3) images.

Enter image specifiers (into the edit box at the top of the screen) either as a full HIPR image filename (eg. cam1.gif) or by a full URL. Only gif files can be loaded. Because of JAVA security, the URL should refer to a publically accessible place, such as your public_html directory.

Pushing the Load Image button or pushing "Return" on the keyboard causes the specified image to be loaded. The input image is displayed in the Input display area below the control buttons, along with the image size.

Operator Instructions

The pull down menu allows you to select what size of kernel will be used in the Gaussian Smoothing phase of the operator. The standard deviation of the Gaussian Smoothing is altered using the box below this menu. The next two boxes, upper and lower threshold, are used to define threshold values which will be used in the tracking stage of the operator. The high threshold defines the initial value which must be passed in order to begin tracking and the low threshold is the value which must be passed in order to continue the tracking.

Image arithmetic may produce images with values less than 0 or greater than 255. These values are clipped to 0 and 255, but Scaling and Offset values can be entered to allow you to rescale the images yourself before the clipping takes place, according to Output = Scaling*Input + Offset.

Edge detector output may produce small values. You can use the scale factor to enhance the visibility.

Known Bugs

You can find out about known problems with the system here.


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©2003 R. Fisher, S. Perkins, A. Walker and E. Wolfart.

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