xil_lookup_create_combined(3)

NAME

xil_lookup_create_combined − create combined lookup tables

SYNOPSIS

#include <xil/xil.h>

XilLookup xil_lookup_create_combined ( XilSystemState State,

XilLookup lookup_list[],
unsigned int num_lookups)

DESCRIPTION

xil_lookup_create_combined () creates a combined lookup table. A combined lookup table is used for transforming multiband data to multiband data. Compare this function with xil_lookup_create(3), which converts single-band data to single-band or multiband data.

Combined lookups are a combination of n single lookup tables, where n is the number of bands in the input image you want to convert. Each single lookup must be a 1-band to 1-band lookup table; the tables must all have the same data type, but each can use a different offset.

To create a lookup table for a multiband input image, you call xil_lookup_create (3) once for each band in the input image, then combine the single lookup tables into a combined lookup table by calling xil_lookup_create_combined ().

xil_lookup_create_combined () returns a handle to a data structure of type XilLookup, which is the combined lookup. The parameter State is a handle to the system-state data structure created when you initialize the XIL library, lookup_list[] is an array of type XilLookup that stores the single lookup tables created for each of the input image’s bands, and num_lookups indicates how many lookup tables are stored in the lookup_list[] array.

ERRORS

For a complete list of XIL error messages by number, consult Appendix B of the XIL Programmer’s Guide.

EXAMPLES

Create a combined lookup table for converting a 24-bit color image to another 24-bit color image whose green band is accented but whose red and blue bands are subdued:

XilSystemState State;
XilLookup lookup_tables[3];
XilLookup combined_lookup_table;
Xil_unsigned8 red[256];/∗ red component of lookup ∗/
Xil_unsigned8 green[256];/∗ green component of lookup ∗/
Xil_unsigned8 blue[256];/∗ blue component of lookup ∗/
int i;
for(i=0; i<256; i++) {
    green[i] = (i + 20) < 255 ? i + 20 : 255;
     blue[i] = red[i] = (i - 10) < 0 ? 0 : i - 10;
}
lookup_tables[0] = xil_lookup_create(State, XIL_BYTE, XIL_BYTE,
                                     1, 256, 0, red);
lookup_tables[1] = xil_lookup_create(State, XIL_BYTE, XIL_BYTE,
                                     1, 256, 0, green);
lookup_tables[2] = xil_lookup_create(State, XIL_BYTE, XIL_BYTE,
                                     1, 256, 0, blue);
combined_lookup_table = xil_lookup_create_combined(State,
                                                   lookup_tables, 3);

Museum