IMAGE_EDGE
Edge Detection in Images

IMAGE_EDGE is a C library which demonstrates the detection of edges in an image.

NEWS is a particularly simple edge detection scheme, which compares the North, East, West, and South neighbors of a pixel to determine if the pixel lies along an edge.

There are many sophisticated edge detection algorithms, and MATLAB has many of them built into its image processing toolbox. The purpose of these examples is simply to demonstrate how a simple version of such edge detection schemes works.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

IMAGE_EDGE is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.

EDGE, a C library which defines some test functions in 1D, 2D and 3D for the detection of edges or discontinuities. It uses GNUPLOT to display the jumps in curves and surfaces.

IMAGE_COMPONENTS, a C library which seeks the connected "nonzero" or "nonblack" components or "segments" of an image or integer vector, array or 3D block.

PBMA_IO, a C library which handles the ASCII Portable Bit Map (PBM) format.

PGMA_IO, a C library which handles the ASCII Portable Gray Map (PGM) format.

• image_edge.c, the source code.
• image_edge.h, the include file.

Examples and Tests:

• image_edge_test.c, a sample calling program.
• image_edge_test.txt, the output file.
• coins.ascii.pgm, an ASCII PGM file containing a grayscale image of coins.
• coins.png, a PNG version of the image.
• coin_edges.ascii.pbm, an ASCII PBM file containing a bitmap image of coins.
• coin_edges.png, a PNG version of the image.

List of Routines:

• I4_HUGE returns a "huge" I4.
• I4MAT_HISTOGRAM computes a histogram of the elements of an I4MAT.
• I4MAT_MAX returns the maximum of an I4MAT.
• NEWS demonstrates the NEWS stencil for edge detection.
• PBMA_WRITE writes the header and data for an ASCII PBM file.
• PBMA_WRITE_DATA writes the data for an ASCII PBM file.
• PBMA_WRITE_HEADER writes the header of an ASCII PBM file.
• PGMA_READ_DATA reads the data in an ASCII PGM file.
• PGMA_READ_HEADER reads the header of an ASCII PGM file.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C source codes.