LBitmap::SelectData

#include "ltwrappr.h"

virtual L_INT LBitmap::SelectData (pDstBitmap, crColor, uSrcLowBit, uSrcHighBit, uThreshold, bCombine, uFlags = 0)

virtual L_INT LBitmap::SelectData (plDstBitmap, crColor, uSrcLowBit, uSrcHighBit, uThreshold, bCombine, uFlags = 0)

Selects a specified number of bits of an 8, 12 or 16-bit grayscale bitmap and puts them into a mask, then colors the bitmap depending on the mask. This can show bitmap variances depending on user-defined conditions.

Returns

Comments

This function is used as a visualization aid. You can select certain bits of the supported type bitmap and show the variances of that bitmap under conditions that you define.

The pDstBitmap should not be allocated when calling this function. That is, you should free the allocated bitmap before calling this function. When the function returns successfully the pDstBitmap will be a 24-bit RGB bitmap.

For 8, 12 and 16-bit grayscale bitmap, the uSrcLowBit can range from 0 to 7, 11, and 15 respectively. However if this value exceeded the range then the function will not return an error, and the pDstBitmap will be a pure black bitmap.

For 8, 12 and 16-bit grayscale bitmap, the uSrcHighBit can range from uSrcLowBit to 7, 11, and 15 respectively. No error will be returned if uSrcHighBit is greater than 7, 11 or 15. The function will return an invalid parameter error if uSrcHighBit < uSrcLowBit.

The function will first construct a mask from bits uSrcLowBit through uSrcHighBit. For each pixel, the pixel value will be combined with the mask using a bitwise and operation. The result will be shifted to the right by uSrcLowBit. This result will be compared with the threshold: if the value is greater than or equal to the threshold, the output pixels color is changed using crColor. If the result is less than the threshold, the output is set to 0.

The following example shows you how to treat a 16-bit grayscale bitmap:

In a16-bit grayscale bitmap, the bits are ordered as b15 b14 b13 ... b2 b1 b0.

For uSrcLowBit = 3, uSrcHighBit = 8, uThreshold = 16 and crColor = RGB(0, 255, 0):

In Source bitmap (pDstBitmap)

------------------- 

b15 b14 b13 b12 b11 b10 b9 |b8 b7 b6 b5 b4 b3| b2 b1 b0

-------------------  

0 1 1 0 1 1 1 0 1 0 0 1 1 1 0 1 

In our case, the mask is 010011 in base 2 (19 in decimal). Since 19 >= 16, the destination pixel will be colored using rcColor. The output pixel will be:

if bCombine = FALSE: crColor = RGB(0,255,0)

if bCombine = TRUE: we take the high byte of the source pixel, which is 01101110 in base 2 (0x6E), and then the value is AND-ed with each component of the crColor. So the output pixel will be RGB(0x00 & 0x6E, 0xFF & 0x6E, 0x00 & 0x6E) which is RGB(0x00, 0x6E, 0x00).

Let us consider another case: the source pixel is 0110111000011101 the mask value is 000011 in base 2(3 in decimal). Since 3 < 16, the destination pixel will be:

if bCombine = FALSE: RGB(0,0,0)

if bCombine = TRUE: The high byte of source pixel will bet set for the RGB, that is RGB(0x6E, 0x6E, 0x6E).

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

This function supports 8, 12 and 16-bit grayscale bitmaps only. Support for 12 and 16-bit grayscale images are available only in the Document/Medical toolkits. It also can process the whole image or a region of the image. If a bitmap has a region, the effect is applied only to the region.

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.

Required DLLs and Libraries

See Also

Example

L_INT LBitmap__SelectDataExample(LBitmap *pLeadBitmap, LBitmap *pSrcBitmap) 
{
   L_INT nRet;
   /* This example applies Selecting. */
   // Call the function
   nRet =pLeadBitmap->SelectData (
                            pSrcBitmap, 
                            RGB(233, 10, 77), 
                            2 /* uSrcLowBit */,
                            6 /* uSrcHighBit */,
                            25 /* uThreshold */,
                            TRUE);
   if(nRet !=SUCCESS)
      return nRet;
   pLeadBitmap->Free ();
   // Now we have the resulted image in pLeadBitmap
   return SUCCESS;
}