Color Label Code (CLC)

Color Representation based on Run Length encoded Images. More...

The Color Label Code is an extension and part of the Run Length Code. The color interpretation of the RLC value (0xFFFF as white and 0 as black) becomes senseless. The CLC contains the color instead, the RLC is only used as switching signal. A header at the beginning of the CLC can store several things:

• a pointer to the referring RLC,
• the maximum color for circular processing (for example, 256, so [0-255] is the color range where the distance between 255 and 0 is the same as between 0 and 1),
• a background color which is used for uninteresting and to-be-ignored regions

An example usage is the input of a vector image from the gradient_3x3_thresh() function, using the magnitude (st) as guide input and the direction (ccmp1) as color. The threshold selects the strong enough edges, and their direction is stored as color at the CLC. Regions with magnitudes lower than the threshold get the background color at the CLC.

Note

Color run length code is only a good choice if the segmentation of the image depends on an additional information, like 'same brightness but different color'

It is important to understand that there is an exact correspondence between Run Length Code entries and color stored in CLC. The byte count of RLC and CLC are identical. This is depicted at the following table. For a better understanding, the RLC and CLC data is displayed side by side.

RLC Meaning	RLC Address (U16*)	CLC Address (U16*)	CLC Value/Meaning
SLC LSB	0 + pRLC	pCLC + 0	RLC LSB
SLC MSB	1 + pRLC	pCLC + 1	RLC MSB
dx	2 + pRLC	pCLC + 2	Maximum Color for Circular Arithmetic, e.g. 128 or 256.
dy	3 + pRLC	pCLC + 3	Designated Color used as Background Color Number.
Line Start Xolor	0 + 4 + pRLC	pCLC + 4 + 0	Color of corresponding RLC Line Segment.
Xolor Toggle	1 + 4 + pRLC	pCLC + 4 + 1	Color of corresponding RLC Line Segment.
...	...	...	...
Xolor Toggle	n - 1 + 4 + pRLC	pCLC + 4 + n - 1	Color of corresponding RLC Line Segment.
dx: End of Line	n + 4 + pRLC	pCLC + 4 + n	-to be ignored-
Line Start Xolor	n + 1 + 4 + pRLC	pCLC + 4 + n + 1	Color of corresponding RLC Line Segment.
...	...	...	...