Determine Color Range

 Keywords: Determine Get Retrieve Color Range RGB Pixel

Question:

I am using some code I found in the tech db to capture pixel colors on the screen. I am trying to write a script to do something based on a color of an object on the screen, the problem is the colors vary a bit. Does anyone know how to figure out a color range? IE in hex or rgb if a color is in the red range return 1, gold return 2, etc. If someone could help me figure this out, it would be greatly be appreciated.

[W15978]

Answer:

This is the VGA color palette.

black #000000
navy #000080 
blue #0000FF 
green #008000 
teal #008080 
lime #00FF00 
aqua #00FFFF 
maroon #800000 
purple #800080 
olive #808000 
gray #808080 
silver #C0C0C0 
red #FF0000 
fuchsia #FF00FF 
yellow #FFFF00 
white #FFFFFF

I would guess you can define a red range like this?

From (red-((red-silver)/2)) 
To (red+((fuchsia-red)/2)-1)

But better read there ...
http://en.wikipedia.org/wiki/RGB_color_model

An RGB triplet (r,g,b) represents the three-dimensional coordinate of the point of the given color within the cube or its faces or along its edges. This approach allows computations of the color similarity of two given RGB colors by simply calculating the distance between them: the shorter the distance, the higher the similarity.

Having a digital 8-bit per channel RGB triplet, each item of red, green, blue has an integer value ramge from 0 to 255 resp. a hex value range from x00 to xFF.

As I understand Wikipedia's description of the three-dimensional Euclidean space, the distance between two points in this space can be evaluated by the formula

Euclidean_Distance_RGB = Sqrt ( (r1 - r2) ** 2 + (g1 - g2) ** 2 + (b1 - b2) ** 2 )

Here comes a small WinBatch script to demonstrate the calculation (my first attempt to this theme ever). How to interprete the results is left to you.

; (c)Detlev Dalitz.20091121.

; In the three-dimensional Euclidean RGB space ...
; the distance between two points (r1, g1, b1) and (r2, g2, b2) is ...
; Euclidean_Distance_RGB = Sqrt ( (r1 - r2) ** 2 + (g1 - g2) ** 2 + (b1 - b2) ** 2 )

#DefineFunction udfEuclideanDistanceRGB (intR1, intG1, intB1, intR2, intG2, intB2)
Return Sqrt ((intR1 - intR2) ** 2 + (intG1 - intG2) ** 2 + (intB1 - intB2) ** 2)
#EndFunction

; 1: pure red color.
intColor1R = 255
intColor1G = 0
intColor1B = 0

; 2: red looking color.
intColor2R = 255
intColor2G = 0
intColor2B = 32

; 3: red looking color.
intColor3R = 255
intColor3G = 64
intColor3B = 32

; 4: color with red amount.
intColor4R = 128
intColor4G = 64
intColor4B = 32


fltColorDistance_1_2 = udfEuclideanDistanceRGB (intColor1R, intColor1G, intColor1B, intColor2R, intColor2G, intColor2B); 32.000000
fltColorDistance_1_3 = udfEuclideanDistanceRGB (intColor1R, intColor1G, intColor1B, intColor3R, intColor3G, intColor3B); 71.554175
fltColorDistance_1_4 = udfEuclideanDistanceRGB (intColor1R, intColor1G, intColor1B, intColor4R, intColor4G, intColor4B); 145.770367

fltColorDistance_2_3 = udfEuclideanDistanceRGB (intColor2R, intColor2G, intColor2B, intColor3R, intColor3G, intColor3B); 64.000000
fltColorDistance_4_3 = udfEuclideanDistanceRGB (intColor4R, intColor4G, intColor4B, intColor3R, intColor3G, intColor3B); 127.000000

Exit

Article ID:   W17924

Filename:   Determine Color Range.txt

File Created: 2014:07:18:09:51:38

Last Updated: 2014:07:18:09:51:38

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