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Flags for the LBitmapBase::Combine Function

Note: Arithmetic calculations in this table assume 24-bit image data.

The following flags define how to treat the source rectangle:

Value	Meaning
CB_SRC_NOP	[0x00000000] No change.
CB_SRC_NOT	[0x00000001] Invert the color, resulting in its complement.
CB_SRC_0	[0x00000002] Change all bits to 0.
CB_SRC_1	[0x00000003] Change all bits to 1.

The following flags define how to treat the destination rectangle:

Value	Meaning
CB_DST_NOP	[0x00000000] No change.
CB_DST_NOT	[0x00000010] Invert the color, resulting in its complement.
CB_DST_0	[0x00000020] Change all bits to 0.
CB_DST_1	[0x00000030] Change all bits to 1.

The following flags define the operation to use when combining the data:

Value	Meaning
CB_OP_AND	[0x00000000] Combine each set of bytes using a bitwise AND (&).
CB_OP_OR	[0x00000100] Combine each set of bytes using a bitwise OR (	).
CB_OP_XOR	[0x00000200] Combine each set of bytes using a bitwise exclusive OR (^).
CB_OP_ADD	[0x00000300] Add the byte values, allowing a maximum of 255.
CB_OP_SUBSRC	[0x00000400] Subtract the source from the destination, allowing a minimum of 0.
CB_OP_SUBDST	[0x00000500] Subtract the destination from the source, allowing a minimum of 0.
CB_OP_MUL	[0x00000600] Multiply the byte values, allowing a maximum of 255. The result is calculated as follows: result = (source * dest) / 255.
CB_OP_DIVSRC	[0x00000700] Divide the destination by the source. If source > 0, then the result is calculated as follows: result = min( (dest / source) * 255, 255 ). Otherwise, if source = 0, then result = 255.
CB_OP_DIVDST	[0x00000800] Divide the source by the destination. If dest > 0, then the result is calculated as follows: result = min( (source / dest) * 255, 255 ). Otherwise, if dest = 0, then result = 255.
CB_OP_AVG	[0x00000900] Use the average of the two values.
CB_OP_MIN	[0x00000A00] Use the lesser of the two values.
CB_OP_MAX	[0x00000B00] Use the greater of the two values.
CB_OP_ABSDIF	[0x00000C00] Calculate the absolute difference between the two values.

The following flags define how to treat the resulting image rectangle:

Value	Meaning
CB_RES_NOP	[0x00000000] No change.
CB_RES_NOT	[0x00001000] Invert the color, resulting in its complement.
CB_RES_0	[0x00002000] Change all bits to 0.
CB_RES_1	[0x00003000] Change all bits to 1.

The following flags define the channel of the source image rectangle:

Value	Meaning
CB_SRC_MASTER	[0x00000000] perform operation on all Channels*.
CB_SRC_RED	[0x00010000] perform operation on Red Channel.
CB_SRC_GREEN	[0x00020000] perform operation on Green Channel.
CB_SRC_BLUE	[0x00030000] perform operation on Blue Channel.

The following flags define the channel of the destination image rectangle:

Value	Meaning
CB_DST_MASTER	[0x00000000] perform operation on all Channels.
CB_DST_RED	[0x00100000] perform operation on Red Channel.
CB_DST_GREEN	[0x00200000] perform operation on Green Channel.
CB_DST_BLUE	[0x00300000] perform operation on Blue Channel.

The following flags define the channel of the resulting image rectangle:

Value	Meaning
CB_RES_MASTER	[0x00000000] perform operation on all Channels.
CB_RES_RED	[0x01000000] perform operation on Red Channel.
CB_RES_GREEN	[0x02000000] perform operation on Green Channel.
CB_RES_BLUE	[0x03000000] perform operation on Blue Channel.

The following flag determines whether to use the raw combine which combines the image data regardless of its palette or LookUpTable (LUT):

Value	Meaning
CB_RAWCOMBINE	[0x04000000] perform a raw combine.

Calculating Master Channel Values

In order to speed up widely used image processing filters in LEADTOOLS, the grayscale value (master channel) of a colored image is calculated using the following formulas:

#define CalcGrayValue(r, g, b) ((L_UCHAR)(((L_UCHAR) (((2 * (L_UINT) (r)) + (5 * (L_UINT) (g)) + (L_UINT) (b) + 4) / 8)))) 
#define CalcGrayValue16(r, g, b) ((L_UINT16) (((2 * (L_UINT32) (r)) + (5 * (L_UINT32) (g)) + (L_UINT32) (b) + 4) / 8)) 
#define CalcGrayValue32(r, g, b) ((L_UINT32) (((2 * (L_UINT32) (r)) + (5 * (L_UINT32) (g)) + (L_UINT32) (b) + 4) / 8))

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