How to get HSV and CMYK colors from pixel?

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VS2012

I've made a color picker tool that gets a ARGB color from a pixel. I've figured out how to get HTML and HEX colors, but can't figure out how to get HSV or CMYK. All the articles that I've found are in C#. I've tried converting a few(with web converters), but I always run into a problem. Here's the code that I'm using to get the ARGB and HTML colors:

PXL_COLOR = bmp.GetPixel(0, 0).ToString 'ARGB

PXL_HTML = System.Drawing.ColorTranslator.ToHtml(bmp.GetPixel(0, 0)) 'HTML

Can someone please help?

Posted 8-Apr-13 2:05am

7774tlas

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2 solutions

Solution 1

If you have RGB you can calculate the CMYK and HSV values.

Have a look at this link: http://www.rapidtables.com/convert/color/index.htm[^]

Example:
R=50 = 50/255 = 0.196
G=100 = 100/255 = 0.392
B=150 = 150/255 = 0.588

K = 1-max(0.196, 0.392, 0.588) = 0.412
C = (1-0.196-0.412)/(1-0.412) = 0.667
M = (1-0.392-0.412)/(1-0.412) = 0.333
Y = (1-0.588-0.412)/(1-0.412) = 0

Posted 8-Apr-13 5:07am

petervanekeren

Updated 8-Apr-13 5:33am

v2

Comments

fjdiewornncalwe 8-Apr-13 12:27pm

My 5. Good resource.

7774tlas 8-Apr-13 15:08pm

Have patience w/ me, I'm horrible at math. This is what I've got so far, but what should I use in place of "max"? I keep getting an error.

Sub RGBtoCMYK()

Dim R As Double
Dim G As Double
Dim B As Double
Dim C As Double
Dim M As Double
Dim Y As Double
Dim K As Double

R = R / 255
G = G / 255
B = B / 255

K = 1 - max(R, G, B)
C = (1 - R - K) / (1 - K)
M = (1 - G - K) / (1 - K)
Y = (1 - B - K) / (1 - K)

End Sub

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petervanekeren · Accepted Answer · 2013-04-08T10:50:00

No Problem.

You can use Math.Max but it only accepts 2 values to compare. Max compares multiple values and retuns the largest one.

This should do the trick :)

VB

Structure CMYK
        Dim C As Double
        Dim M As Double
        Dim Y As Double
        Dim K As Double
    End Structure

    Structure RGB
        Dim R As Double
        Dim G As Double
        Dim B As Double
    End Structure

    Private Function RGBtoCMYK(ByVal rgbIn As RGB) As CMYK
        Dim cmykOut As CMYK
        With rgbIn
            .R = .R / 255
            .G = .G / 255
            .B = .B / 255
        End With
        'math.max only accepts 2 aguments to compare. 
        'Put all the values in an array and get the .Max of the array
        Dim arr(2) As Double
        arr(0) = rgbIn.R
        arr(1) = rgbIn.G
        arr(2) = rgbIn.B

        With cmykOut
            .K = 1 - arr.Max
            .C = (1 - rgbIn.R - .K) / (1 - .K)
            .M = (1 - rgbIn.G - .K) / (1 - .K)
            .Y = (1 - rgbIn.B - .K) / (1 - .K)
        End With
        Return cmykOut
    End Function

You can call the funtion usings something like

VB

Dim colorIn As RGB
   With colorIn
      .R = 50
      .G = 100
      .B = 150
   End With
Dim colorOut As CMYK = RGBtoCMYK(colorIn)