L_EdgeDetectorBitmap
#include "l_bitmap.h"
L_INT EXT_FUNCTION L_EdgeDetectorBitmap(pBitmap, uThreshold, uFilter)
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pBITMAPHANDLE pBitmap; |
/* pointer to the bitmap handle */ |
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L_UINT uThreshold; |
/* threshold value */ |
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L_UINT uFilter; |
/* filter to be used */ |
Applies the specified edge filter to the specified bitmap.
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Parameter |
Description |
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pBitmap |
Pointer to the bitmap handle that references the bitmap on which to apply the edge filter. |
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uThreshold |
Threshold value used to determine which pixels are edge pixels. If the difference determined for a pixel is greater than this value, the pixel is an edge pixel. |
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uFilter |
Flag that indicates which edge detection filter to apply. Possible values are: |
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Value |
Meaning |
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EDG_SOBEL_VERT |
[0x0101] Detect the vertical edges |
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EDG_SOBEL_HORZ |
[0x0102] Detect the horizontal edges |
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EDG_SOBEL_ALL |
[0x0103] Detect horizontal & vertical edges |
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EDG_PREWITT_VERT |
[0x0201] Detect the vertical edges |
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EDG_PREWITT_HORZ |
[0x0202] Detect the horizontal edges |
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EDG_PREWITT_ALL |
[0x0203] Detect horizontal & vertical edges |
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EDG_LAPLACE_1 |
[0x0301] Detect vertical & horizontal edges |
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EDG_LAPLACE_2 |
[0x0302] Detect general edges |
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EDG_LAPLACE_3 |
[0x0303] Detect general edges. (The filter used for this option is different than the filter used for the EDG_LAPLACE_2 filter.) |
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EDG_LAPLACE_DIAG |
[0x0304] Detect the diagonal edges |
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EDG_LAPLACE_HORZ |
[0x0305] Detect the horizontal edges |
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EDG_LAPLACE_VERT |
[0x0306] Detect the vertical edges |
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EDG_GRADIENT_N |
[0x0401] Detect north edges |
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EDG_GRADIENT_NE |
[0x0402] Detect north east edges |
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EDG_GRADIENT_E |
[0x0403] Detect east edges |
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EDG_GRADIENT_SE |
[0x0404] Detect south east edges |
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EDG_GRADIENT_S |
[0x0405] Detect south edges |
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EDG_GRADIENT_SW |
[0x0406] Detect south west edges |
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EDG_GRADIENT_W |
[0x0407] Detect west edges |
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EDG_GRADIENT_NW |
[0x0408] Detect north west edges |
Returns
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SUCCESS |
The function was successful. |
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< 1 |
An error occurred. Refer to Return Codes. |
Comments
Filters such as Sobel filter, Prewitt filter, Laplacian filter, and Gradient filter are used to determine the pixels belonging to edges in the bitmap.
This function can process the whole image or a region of the image.
This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.
The threshold range for the 16, 48, and 64-bit bitmaps is from 0 to 65535 and for 12-bit bitmaps from 0 to 4095. Otherwise, it is from 0 to 255. The threshold is applied on channels separately.
This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.
Required DLLs and Libraries
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LTIMG For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application. |
Platforms
Windows 95 / 98 / Me, Windows 2000 / XP, Windows CE.
See Also
Example
/* This example loads a bitmap and finds its edges. */
BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image. */
/* Load the bitmap, keeping the bits per pixel of the file */
L_LoadBitmap (TEXT("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
/* find the edges of the bitmap */
L_EdgeDetectorBitmap (&LeadBitmap,60, EDG_SOBEL_ALL);