Specifications

Histogram, Threshold, and Compare Functions
10-5
10
Lookup Table (LUT) and Histogram Operations
A LUT can be used to specify an intensity transformation. Given an input
intensity, LUT can be used to look up an output intensity. Usually a LUT is
provided for each channel in the image, although sometimes the same LUT
can be shared by many channels.
The IplLUT Structure
You can set a lookup table using the IplLUT structure. The C language
definition of the
IplLUT structure is as follows:
IplLUT Structure Definition
typedef struct _IplLUT {
int num; /* number of keys or values */
int* key ;
int*
value ;
int* factor ;
int interpolateType ;
} IplLUT;
The key array has the length num ;the value and factor are arrays of the
same length
num -1.The interpolateType can be either
IPL_LUT_LOOKUP or IPL_LUT_INTER.
Consider the following example of
num =4:
key value factor
k0 v0 f0
k1 v1 f1
k2 v2 f2
k3