LBitmap::DeskewCheck

#include "ltwrappr.h"

L_INT LBitmap::DeskewCheck(pnAngle=NULL, crBack, uFlags)

L_INT32 * pnAngle;	/* address of the variable to be updated */
COLORREF crBack;	/* fill color */
L_UINT uFlags;	/* flags*/

Rotates the specified bank check bitmap to straighten it.

Parameter	Description
pnAngle	Address of the variable to be updated with the amount that the function rotates the image. The amount of rotation is expressed in hundredths of degrees. For example, 500 mean 5 degrees clockwise. You can pass NULL if you do not need to check the amount of rotation. Valid values range from -2000 to 2000
crBack	Color used to fill the background following rotation. This is used only if DSKW_FILL is set in uFlags.
uFlags	Flags that indicate whether or not to deskew the image and what background color to use. You can use a bitwise OR (\|) to specify one flag from each group.
	The following flags indicate whether to deskew the image after the function finds the skew angle:
	Value	Meaning
	DSKW_PROCESS	[0x00000000] Deskew (rotate) the image. This is the default value.
	DSKW_NOPROCESS	[0x00000001] Don't deskew (rotate) the image. Generally this flag is used to find the angle of rotation.
	The following flags indicate what background color to use:
	Value	Meaning
	DSKW_FILL	[0x00000000] Use the color in crBack to fill areas exposed after rotation. This is the default value.
	DSKW_NOFILL	[0x00000010] Let the function automatically find the suitable background color used to fill areas exposed after rotation. crBack is ignored in this case.
	The following flags indicate which type of interpolation to perform:
	Value	Meaning
	DSKW_LINEAR	[0x00000000] Do not perform interpolation when rotating.
	DSKW_RESAMPLE	[0x00001000] Perform bilinear interpolation when rotating.
	DSKW_BICUBIC	[0x00002000] Perform bicubic interpolation when rotating.
	The following flags indicate the image type:
	Value	Meaning
	DSKW_DOCUMENTIMAGE	[0x00000000] The image contains text only. This is the default value.
	DSKW_DOCUMENTANDPICTURE	[0x00010000] The image contains text and pictures or light text.
	The following flags indicate the rotation type:
	Value	Meaning
	DSKW_NORMALSPEEDROTATE	[0x00000000] Rotate at normal speed (high quality). This is the default value.
	DSKW_HIGHSPEEDROTATE	[0x00100000] Rotate at high speed (moderate quality, only for 1-bit images)
	The following flags indicate which deskew algorithm to use:
	Value	Meaning
	CHECK_DESKEW_NOT_USED	[0x00000000] Do not perform any of the bank check algorithms. Perform the ordinary deskew. This is the default value.
	CHECK_DESKEW_NORMAL	[0x01000000] Use the bank check algorithm to deskew the bitmap. This algorithm considers many features common to standard bank checks in order to determine orientation.
	CHECK_DESKEW_DETECT_LINES	[0x02000000] Use the line detection algorithm to deskew the bitmap.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Like LBitmap::Deskew, you can use this function to automatically straighten scanned documents. For an example, click here.

LBitmap::DeskewCheck is designed to work especially on bank check images. The following algorithms can be used:

the normal deskew algorithm
a special bank check algorithm
a special line detection algorithm).

If uFlags contains DSKW_NOPROCESS, the function will update pnAngle with the deskew angle, without rotating the image.

Bitmaps can be rotated by as much as 20 degrees in either direction. This function is intended for bank check images that are mainly horizontal lines of text. The results are less predictable with other types of images.

To update a status bar or detect a user interrupt during execution of this function, refer to LBase::EnableStatusCallback.

This function does not support 12 and 16-bit grayscale and 48 and 64-bit color images. If the image is 12 and 16-bit grayscale and 48 and 64-bit color, the function will not return an error.

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.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

LTDIS

LTFIL

LTIMGCOR

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

See Also

Functions:	LBitmap::Deskew, LBitmap::Despeckle, LBitmap::WindowLevel, LBitmap::AutoBinarize, LBitmap::DynamicBinary, LBitmap::AutoBinary, Class Members
Topics:	Raster Image Functions: Doing Geometric Transformations
	Raster Image Functions: Filtering Images
	Processing an Image
	Using Color Values in LEADTOOLS
	Raster Image Functions: Processing an Image
	Deskewing

Example

L_INT LBitmap__DeskewCheckExample()
{
   L_INT nRet;
   LBitmap LeadBitmap;
   L_INT32 lRotatedAngle;
   L_TCHAR szDummyBuffer[50];
   nRet =LeadBitmap.Load(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\clean.tif"), 0,ORDER_BGR);
   if(nRet !=SUCCESS)
      return nRet;
   // Deskew the image, and get the angle with which the image was rotated
   nRet =LeadBitmap.DeskewCheck (&lRotatedAngle, RGB(0,0,0), CHECK_DESKEW_DETECT_LINES | DSKW_HIGHSPEEDROTATE | DSKW_PROCESS | DSKW_NOFILL | DSKW_DOCUMENTIMAGE);
   if(nRet !=SUCCESS)
      return nRet;
   wsprintf(szDummyBuffer, TEXT("The image was rotated with %d degrees"), lRotatedAngle/100);
   MessageBox(0, szDummyBuffer, TEXT("Check Deskew"), MB_OK);
   
   return SUCCESS;
}