color.h

Contains functions for normalized grey scale color sensing.

color type

The struct type for color sensors is defined as

typedef struct Color
{
    sensor s;
    double k, l;
}
color;

consisting of a color sensor object (s) and calibration parameters k and l.

Constructor

The constructor for color is defined as

color colorNew(char sport);

where sport is the port of the designated color sensor in a character format.

If, for example, a color sensor is connected to the port 2, the corresponding color would be constructed using

color foo;
foo = colorNew('2');

Note, the default color profile (defined by k and l fields), where k = 1.0 and l = 0.0, is used when constructing color. The profile can be changed manually by changing the values of k and l fields manually,

...
foo.k = 2.33;
foo.l = 1.23;

or by using colorProfileCalib,

...
colorProfileCalib(&foo, "path/to/some/profile_k", "path/to/some/profile_l");

or colorProfileLoad,

...
colorProfileLoad(&foo, "path/to/some/profile_k", "path/to/some/profile_l");

functions.

Functions

double colorRead(color cs);

• reads and returns normalized grey scale color value from color sensor in %
• Parameters:
  • color cs - color sensor object

void colorProfileCalib(color *cs, char *profile_k, char *profile_l);

• calibrates and loads color profile
• Parameters:
  • color *cs - pointer to color sensor object
  • char *profile_k - k profile file name string
  • char *profile_l - l profile file name string

void colorProfileLoad(color *cs, char *profile_k, char *profile_l);

• loads color profile from profile files
• Parameters:
  • color *cs - pointer to color sensor object
  • char *profile_k - k profile file name string
  • char *profile_l - l profile file name string

Color normalization

Suppose the k and l are the sensor calibration parameters, then the normalization of sensor reading is calculated by

normalized reading = k * ( reading + l )

The k and l parameters are derived from the raw readings of black and white color values and are calculated as

k = 100 / (white - black)

and

l = - black

The colorProfileCalib function uses the averages 50 raw readings of black and white to achieve greater accuracy when calibrating k and l parameters. This number is hard-coded, but can be modified easily by changing the code under // read and sum some number of values and // divide by number of values read comments in color.c.