L_ColorThresholdBitmap (original) (raw)
Summary
Using any one of eight color spaces, resets those bitmaps pixel component values that fall inside or outside of a specified range.
Syntax
#include "l_bitmap.h"
L_LTIMGCLR_API L_INT L_ColorThresholdBitmap (pBitmap, uColorSpace, pCompData, uFlags)
Parameters
pBITMAPHANDLE pBitmap
Pointer to the bitmap handle that references the bitmap on which to apply the effect.
L_UINT uColorSpace
Color space which the threshold is based on. Possible values are
| Value | Meaning |
|---|---|
| CLTH_RGB_SPACE | [0x00000000] RGB color space |
| CLTH_HSV_SPACE | [0x00000001] HSV color space |
| CLTH_HLS_SPACE | [0x00000002] HLS color space |
| CLTH_XYZ_SPACE | [0x00000003] XYZ color space |
| CLTH_YCrCb_SPACE | [0x00000004] YCrCb color space |
| CLTH_YUV_SPACE | [0x00000005] YUV color space |
| CLTH_LAB_SPACE | [0x00000006] LAB color space |
| CLTH_CMY_SPACE | [0x00000007] CMY color space |
pCOMPDATA pCompData
Pointer to an array of 3 COMPDATA structures that contains the parameters used to compare and modify each component.
L_UINT32 uFlags
Reserved for future use. Must be 0.
Returns
| Value | Meaning |
|---|---|
| SUCCESS | The function was successful. |
| < 1 | An error occurred. Refer to Return Codes. |
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.
This function is similar to the L_ConvertColorSpace function but provides greater flexibility by allowing the specification of a range and different options for handling those values that fall outside of the range. Please note that every color space component may have a different range.
| Color Component | Range for 8-bit components | Range for 16-bit components |
|---|---|---|
| RGB | ||
| R | 0 - 255 | 0 - 65535 |
| G | 0 - 255 | 0 - 65535 |
| B | 0 - 255 | 0 - 65535 |
| HSV | ||
| H | 0 - 360 | 0 - 36000 |
| S | 0 - 100 | 0 - 10000 |
| V | 0 - 255 | 0 - 65535 |
| HLS | ||
| H | 0 - 360 | 0 - 36000 |
| L | 0 - 255 | 0 - 65535 |
| S | 0 - 100 | 0 - 10000 |
| XYZ | ||
| X | 0 - 255 | 0 - 65535 |
| Y | 0 - 255 | 0 - 65535 |
| Z | 0 - 255 | 0 - 65535 |
| YCrCb | ||
| Y | 0 - 255 | 0 - 65535 |
| Cr | -128 - 127 | -32768 - 32767 |
| Cb | -128 - 127 | -32768 - 32767 |
| YUV | ||
| Y | 0 - 255 | 0 - 65535 |
| U | -112 - 111 | -28567 - 28566 |
| V | -138 - 137 | -35337 - 35336 |
| LAB | ||
| L | 0 - 100 | 0 - 10000 |
| A | -128 - 127 | -32768 - 32767 |
| B | -128 - 127 | -32768 - 32767 |
| CMY | ||
| C | 0 - 255 | 0 - 65535 |
| M | 0 - 255 | 0 - 65535 |
| Y | 0 - 255 | 0 - 65535 |
This function works as follows:
- The bitmap is converted to the required color space.
- For every pixel, the following operations are performed: Each component is compared with the nMinRange and nMaxRange ranges of the appropriate COMPDATA structure.
- If it is inside the range, the component is considered to have "passed" the test.
- If it is outside the range, the component has been rejected". The CLTH_TYP_BANDREJECT flag inverts this by making "rejected" components "passed" and viceversa.
- If CLTH_MOD_CHANNEL is set, the components are modified independently. If CLTH_MOD_ALL has been passed, the pixel is rejected by the test if any component is rejected. If the pixel/component is rejected, then:
a. If CLTH_VALUE_MIN is passed, the rejected pixel/component is set to 0.
b. If CLTH_VALUE_MAX is passed, the rejected pixel/component is set to 255.
c. If CLTH_VALUE_CLAMP is passed, components less that nMin go to 0 and components greater than nMax go to 255. This would work only with the CLTH_MOD_CHANNEL and CLTH_TYP_BANDPASS flag.
This function works for 1, 2, 3, 8,16, 24, 32, 48 and 64-bit color bitmaps and can support regions for 24 and 48-bit bitmaps. If a 24 or 48-bit bitmap has a region the effect will be applied on the region only.
One structure is used for each color component. The order is considered to be the same as in the CLTH_xxx_SPACE name. For example, for CLTH_RGB_SPACE:
- pCompData[0] structure is used for the Blue component
- pCompData[1] structure is used for the Green component
- pCompData[2] structure is used for the Red component
The pCompData[0].uStructSize must be set to sizeof(COMPDATA) before calling this function. For an array of structures, only the first structure in the array needs to have uStructSize member set.
To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.
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.
Color Threshold Function - Before
Color Threshold Function - After
View additional platform support for this Color Threshold function.
Required DLLs and Libraries
- LTIMGCLR
- 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_BinaryFilterBitmap
- L_ConvertColorSpace
- L_ColorSeparateBitmap
- L_ColorMergeBitmap
- L_AddBitmapNoise
- L_IntensityDetectBitmap
- L_SpatialFilterBitmap
- L_BinaryFilterBitmap
- L_MaxFilterBitmap
- L_MinFilterBitmap
- L_AddShadowBitmap
- L_ChangeHueSatIntBitmap
- L_ColorThresholdBitmap
- L_DFTBitmap
- L_AllocFTArray
- L_DirectionEdgeStatisticalBitmap
- L_FFTBitmap
- L_FreeFTArray
- L_FrqFilterBitmap
- L_FrqFilterMaskBitmap
- L_FTDisplayBitmap
- L_GetBitmapStatisticsInfo
- L_GetFeretsDiameter
- L_GetObjectInfo
- L_GetRgnContourPoints
- L_GetRgnPerimeterLength
- L_MathFunctionBitmap
- L_RevEffectBitmap
- L_SegmentBitmap
- L_SubtractBackgroundBitmap
- L_UserFilterBitmap
- L_AdjustBitmapTint
- L_ColorHalfToneBitmap
Topics
- Raster Image Functions: Modifying Intensity Values
- Correcting Colors
- Raster Image Functions: Getting and Setting Pixel Values
- Raster Image Functions: Doing Color Space Conversions
- Raster Image Functions: Correcting Colors
Example
L_INT ColorThresholdBitmapExample(L_VOID)
{
L_INT nRet;
BITMAPHANDLE LeadBitmap; /* Bitmap handle for the image */
COMPDATA pCompData[3];
L_INT nI;
/* Load a bitmap at its own bits per pixel */
nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("Image1.jpg")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
if (nRet != SUCCESS)
return nRet;
pCompData[0].uStructSize = sizeof(COMPDATA);
for (nI = 0; nI < 3; nI++)
{
pCompData[nI].nMinRange = 128;
pCompData[nI].nMaxRange = 255;
pCompData[nI].uFlags = 0;
}
/* Apply color Threshold effect on the image*/
nRet = L_ColorThresholdBitmap(&LeadBitmap, CLTH_RGB_SPACE, pCompData, 0);
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;
}