L_ColorThresholdBitmap
#include "l_bitmap.h"
L_INT EXT_FUNCTION L_ColorThresholdBitmap (pBitmap, uColorSpace, pCompData)
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pBITMAPHANDLE pBitmap; |
/* pointer to the bitmap handle */ |
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L_UINT uColorSpace; |
/* color space */ |
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LPCOMPDATA pCompData; |
/* pointer to an array of structures */ |
Using any one of eight color spaces, resets those bitmap’s pixel component values that fall inside or outside of a specified range.
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Parameter |
Description |
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pBitmap |
Pointer to the bitmap handle that references the bitmap on which to apply the effect. |
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uColorSpace |
Color space which the threshold is based on. Possible values are |
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Value |
Meaning |
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CLTH_RGB_SPACE |
[0x00000000] RGB color space |
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CLTH_HSV_SPACE |
[0x00000001] HSV color space |
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CLTH_HLS_SPACE |
[0x00000002] HLS color space |
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CLTH_XYZ_SPACE |
[0x00000003] XYZ color space |
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CLTH_YCrCb_SPACE |
[0x00000004] YCrCb color space |
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CLTH_YUV_SPACE |
[0x00000005] YUV color space |
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CLTH_LAB_SPACE |
[0x00000006] LAB color space |
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CLTH_CMY_SPACE |
[0x00000007] CMY color space |
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pCompData |
Pointer to an array of 3 COMPDATA structures that contains the parameters used to compare and modify each component. |
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Returns
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SUCCESS |
The function was successful. |
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< 1 |
An error occurred. Refer to Return Codes. |
Comments
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.
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Color Component |
Range for 8-bit components |
Range for 16-bit components |
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RGB |
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R |
0 – 255 |
0 - 65535 |
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G |
0 – 255 |
0 - 65535 |
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B |
0 – 255 |
0 - 65535 |
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HSV |
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H |
0 - 360 |
0 - 36000 |
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S |
0 - 100 |
0 - 10000 |
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V |
0 - 255 |
0 - 65535 |
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HLS |
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H |
0 - 360 |
0 - 36000 |
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L |
0 - 255 |
0 - 65535 |
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S |
0 - 100 |
0 - 10000 |
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XYZ |
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X |
0 - 255 |
0 - 65535 |
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Y |
0 - 255 |
0 - 65535 |
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Z |
0 - 255 |
0 - 65535 |
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YCrCb |
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Y |
0 - 255 |
0 - 65535 |
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Cr |
-128 - 127 |
-32768 - 32767 |
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Cb |
-128 - 127 |
-32768 - 32767 |
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YUV |
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Y |
0 - 255 |
0 - 65535 |
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U |
-112 - 111 |
-28567 - 28566 |
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V |
-138 - 137 |
-35337 - 35336 |
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LAB |
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L |
0 - 100 |
0 - 10000 |
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A |
-128 - 127 |
-32768 - 32767 |
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B |
-128 - 127 |
-32768 - 32767 |
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CMY |
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C |
0 - 255 |
0 - 65535 |
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M |
0 - 255 |
0 - 65535 |
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Y |
0 - 255 |
0 - 65535 |
This function works as follows:
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1. |
The bitmap is converted to the required color space. |
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2. |
For every pixel, the following operations are performed: Each component is compared with the nMinRange and nMaxRange ranges of the appropriate COMPDATA structure. |
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a. |
If it is inside the range, the component is considered to have "passed" the test. |
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b. |
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. |
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3. |
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: |
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a. |
If CLTH_VALUE_MIN is passed, the rejected pixel/component is set to 0. |
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b. |
If CLTH_VALUE_MAX is passed, the rejected pixel/component is set to 255. |
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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 signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.
Required DLLs and Libraries
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LTIMG 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
Windows 95 / 98 / Me, Windows 2000 / XP.
See Also
Example
BITMAPHANDLE LeadBitmap; /* Bitmap handle for the image */
COMPDATA pCompData[3];
L_INT nI;
/* Load a bitmap at its own bits per pixel */
L_LoadBitmap(TEXT("IMAGE3.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
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*/
L_ColorThresholdBitmap(&LeadBitmap, CLTH_RGB_SPACE, pCompData);