TImageEnProc.EdgeDetect_ShenCastan
Declaration
procedure EdgeDetect_ShenCastan(Ratio: Double = 0.99; Smooth: Double = 0.9; WindowSize: Integer = 7; ThinFactor: Integer = 0; DoHysteresis: Boolean = true);Description
Convert the current color image to black & white (1 bit) using a Shen-Castan (ISEF) edge detection algorithm.The Shen-Castan algorithm convolves the image with the Infinite Symmetric Exponential Filter, computes the binary Laplacian image, suppresses false zero crossing, performs adaptive gradient thresholding, and, finally, also applies hysteresis thresholding. (Algorithms for Image Processing and Computer Vision - J.R.Parker).
| Parameter | Description |
|---|---|
| Ratio | Percent of pixels to be above High threshold (recommended: 0.99) |
| Smooth | Smoothing factor (recommended: 0.9) |
| WindowSize | Size of window for adaptive gradient (recommended: 7, max: 50) |
| ThinFactor | Thinning factor (recommended: 0) |
| DoHysteresis | If True tun on the hysteresis thresholding (recommended: True) |
Note: Edge detection is performed on entire image. It is not affected by any selection
Demos
 | Demos\ImageEditing\CompleteEditor\PhotoEn.dpr |
| | Demos\ImageEditing\EveryMethod\EveryMethod.dpr |
Method Comparison
ImageEnView1.IO.LoadFromFile( 'D:\TestImage.jpg' );
// Convert the current color image to black & white (1 bit) using a Shen-Castan (ISEF) edge detection algorithm
ImageEnView1.Proc.EdgeDetect_ShenCastan();
// Detect the edges of objects within an image using a Sobel filter
ImageEnView1.Proc.EdgeDetect_Sobel();
