RGB VS HSL VS HSV

• color spaces

A mathematical model that describes colors as tuples of numbers. We can represent and visualize the same image using different color spaces by RGB, HSV, HLS.

 

• Grayscale images

an example of a grayscale image

 

A single channel images that only contain information about the intensity of the light.

Each pixel value indicates the amount of light for that pixel.

It usually describe this intensity with a 8-bit integer.

We can see how each object has a different intensity.

 

• RGB

 

Each pixel of the image is described as a tuple of three values. These values are 8-bit integer.

A RGB image is made of three channels, one for each color of the model.

 

Limitaions

- Non linear color model

- Hard to determine specific colors

 

• Hue

A single number between zero and 360 that specifies the color.

color encoding, angle[0,360]

 

• Lightness and Value

Relative lightness of darkness of a color [0,1]

 

• Saturation

Measurement of colorfulness [0,1]

 

• HSL

Hue Saturation Lightness

 

• HSV

Hue Saturation Value

 

 

HSV (hue, saturation, value) colorspace is a model to represent the colorspace similar to the RGB color model.  Variation of the saturation goes from unsaturated to represent shades of gray and fully saturated (no white component). Value channel describes the brightness or the intensity of the color. 

 

H, S : Adjust the color

V : Adjust the brightness

So if you specify only the H and S ranges, you can extract color areas even in dark images.

 

https://docs.opencv.org/3.4/da/d97/tutorial_threshold_inRange.html