LBitmapRgn::SetRgnColorRGBRange

#include "ltwrappr.h"

virtual L_INT LBitmapRgn::SetRgnColorRGBRange(crLower, crUpper)

Creates or updates the bitmap region by adding a region that consists of all the pixels that fall in the range crLower ... crUpper, inclusively.

Returns

Comments

This function uses the RGB color model to set a region based on a color range.

To be added to the region a color must fall in the range crLower..crUpper. To set a region for all pure red, specify crLower and crUpper as follows:

crLower RGB(1,0,0)
crUpper(255,0,0)

Note that this would fail to include many colors that look red to the eye (like RGB(255,4,4)). To include ALL shades of red, you can use LBitmapRgn::SetRgnColorHSVRange.

To update an existing region, specify how the new region is to be combined with the existing one. For descriptions of the possibilities, refer to Creating a Bitmap Region.

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 standard Windows values for COLORREF represent either red, green, and blue color values, or an index into the bitmap's palette. A COLORREF value with the format 0x00BBGGRR represents the blue, green, and red color values for the specified pixel, where 0xBB is the blue value, 0xGG is the green value and 0xRR is the red value. If 0x01000000 is set in the COLORREF value (0x010000ZZ), the lower 8 bits (0xZZ) represent an index into the bitmap's palette which holds the color value. These COLORREF values can be used with any Windows function and macro that takes a COLORREF parameter.

In the Document/Medical Imaging editions, the COLORREF value may represent a 16 bit grayscale value if pBitmap is a 12 or 16-bit grayscale bitmap, or a 32-bit grayscale value if pBitmap is a 32-bit grayscale bitmap. So that the value is not confused with an RGB value, the COLORREF_GRAY16 mask (0x04000000) is set. In this case (0x0400YYYY), the lower 16 bits (0xYYYY) of the COLORREF value represent the 16-bit grayscale value. (0x0400FFFF is 16-bit white and 0x04000000is 16-bit black.) This is not a standard Windows value. Therefore, LEADTOOLS functions will recognize a COLORREF having this format, but Windows functions will not. For information on how to use a 16-bit grayscale COLORREF in a non-LEADTOOLS function, refer to LBitmapBase::GetPixelColor.

If working with 12 and 16-bit grayscale, and (crLower and crUpper) values represent the 16-bit grayscale values, then the function will work on the data. For example, you must do the following if you want to select the rage between 100 and 130:

 nValue = 100;

 rgbLo = nValue | COLORREF_GRAY16;

 nValue = 130;

 rgbHi = nValue | COLORREF_GRAY16;

Required DLLs and Libraries

See Also

Example

//This example sets a region corresponding to all colors that

//have an rgb that includes red but no green and no blue

L_INT LBitmapRgn__SetRgnColorRGBRangeExample(LBitmapRgn& rgn)
{
   COLORREF rgbLo, rgbHi;
   L_INT nRet;
   rgbLo = RGB(1,0,0);
   rgbHi = RGB(255,0,0);
   nRet = rgn.SetRgnColorRGBRange(rgbLo,rgbHi);
   return nRet;
}