L_HalfTonePatternBitmap

Summary

Creates a halftone screen effect for an image while keeping its continuous range of tones.

Syntax

L_LTIMGCOR_API L_INT L_HalfTonePatternBitmap(pBitmap, uContrast, uRipple, uAngleContrast, uAngleRipple, nAngleOffset, crForGround, crBackGround, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to be changed.

L_UINT uContrast

Halftone pattern contrast. Increasing this value increases the pattern brightness, making it more visible.

L_UINT uRipple

Halftone pattern frequency. Internally, this value is divided by 100. For example, if uRipple = 200 the actual frequency is 2. Increasing this value increases the number of dots, lines, etc. in the pattern.

L_UINT uAngleContrast

Angular pattern contrast. Angular pattern only occurs if either HTPATTERN_CIRCLE or HTPATTERN_ELLIPSE option is selected. Increasing this value increases brightness of the "spokes" in the image.

L_UINT uAngleRipple

Angular pattern frequency. This parameter is used when either HTPATTERN_CIRCLE or HTPATTERN_ELLIPSE option is selected. This value determines how many "spokes" appear in the image.

L_INT nAngleOffset

Angular pattern offset in a hundredths of degrees (+/-). A positive value will rotate the screen clockwise, while a negative value will rotate the screen counter-clockwise. This parameter is used when either the HTPATTERN_CIRCLE or HTPATTERN_ELLIPSE option is selected.

COLORREF crForGround

The COLORREF value that specifies the foreground color for any exposed areas. You can specify a COLORREF value, such as the return value of the Windows RGB macro, or you can use the PALETTEINDEX macro to specify a palette color.

COLORREF crBackGround

The COLORREF value that specifies the background color for any exposed areas. You can specify a COLORREF value, such as the return value of the Windows RGB macro, or you can use the PALETTEINDEX macro to specify a palette color.

L_UINT uFlags

Flag that indicates which halftone pattern type to use. Possible values are:

Returns

Comments

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.

Use this function to create a halftone screen effect for an image while keeping its continuous range of tones. Use the uContrast parameter to control the amount of the midtones in the image.

Use the L_ColorHalfToneBitmap to create an enlarged halftone screen for each image channel. The filter divides the image into rectangles and replaces each rectangle with circles, one for each channel. The size of each circle is proportional to the brightness of the rectangle which it is replacing.

Use the L_HalfToneBitmap function to convert a 1-, 4-, 8-, 16-, 24-, or 32-bit bitmap to a halftoned bitmap, with a specified pattern rotation. A halftoned bitmap is a 1-bit bitmap that has been dithered for black and white printing or display.

Use the L_GrayScaleBitmapExt function to convert any bitmap to a gray scale bitmap without changing its resolution.

For an example, click here

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

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 in the Document and Medical Imaging toolkits.

If the bitmap has a region, this function works only on the region. If the bitmap does not have a region, this function works on the entire bitmap.

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.

View additional platform support for this Halftone Pattern function.

Required DLLs and Libraries

• 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.

Platforms

Win32, x64, Linux.

See Also

Functions

• L_DefaultDithering
• L_GrayScaleBitmap
• L_GrayScaleBitmapExt
• L_AutoColorLevelBitmap
• L_ColorLevelBitmap
• L_CorrelationBitmap
• L_GrayScaleToDuotone
• L_GrayScaleToMultitone
• L_HolesRemovalBitmapRgn
• L_SelectiveColorBitmap
• L_SkeletonBitmap
• L_HalfToneBitmap
• L_PointillistBitmap
• L_ColorHalfToneBitmap
• L_ColorSeparateBitmap
• L_ColorMergeBitmap
• L_DesaturateBitmap
• L_GetBitmapStatisticsInfo
• L_GetBitmapHistogram
• L_GetBitmapColorCount
• L_GetBitmapColors
• L_GetMinMaxBits
• L_GetMinMaxVal
• L_ConvertToColoredGray
• L_ColorizeGrayBitmap
• L_GetBitmapAlpha
• L_ShiftBitmapData
• L_SelectBitmapData
• L_AnnSetAutoHilightPen
• L_AnnSetAutoCursor
• L_IsGrayScaleBitmap
• L_WindowLevel
• L_WindowLevelBitmap
• L_WindowLevelFillLUT

Topics

• Raster Image Functions: Doing Color Expansion or Reduction
• Raster Image Functions: Filtering Images
• Applying Artistic Effects

Example

The following example loads a bitmap and applies the halftone pattern filter

L_INT HalfTonePatternBitmapExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap; 
 
   /* Load the bitmap, keeping the bits per pixel of the file */ 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("Sample1.CMP")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   /*Apply the filter*/ 
   nRet = L_HalfTonePatternBitmap(&LeadBitmap, 100, 200, 12, 2, 4500, RGB(255, 255, 255), RGB(255, 0, 0), HTPATTERN_LINE); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   //free bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return SUCCESS; 
}