How do I invert a colour?

user_67258 0
Viewed 79557

I know that this won't directly invert a colour, it will just 'oppose' it. I was wondering if anyone knew a simple way (a few lines of code) to invert a colour from any given colour?

At the moment I have this (which isn't exactly the definition of an invert, because if I pass it a grey / gray colour it will return something extremely similar e.g. 127, 127, 127):

const int RGBMAX = 255;

Color InvertMeAColour(Color ColourToInvert)
{
    return Color.FromArgb(RGBMAX - ColourToInvert.R, 
      RGBMAX - ColourToInvert.G, RGBMAX - ColourToInvert.B);
}
system.drawing.color colors .net c#
8 Answers

It depends on what do you mean by "inverting" a color

Your code provides a "negative" color.

Are you looking for transform red in cyan, green in purple, blue in yellow (and so on) ? If so, you need to convert your RGB color in HSV mode (you will find here to make the transformation).

Then you just need to invert the Hue value (change Hue by 360-Hue) and convert back to RGB mode.

EDIT: as Alex Semeniuk has mentioned, changing Hue by (Hue + 180) % 360 is a better solution (it does not invert the Hue, but find the opposite color on the color circle)

user_1295560

Try this:

uint InvertColor(uint rgbaColor)
{
    return 0xFFFFFF00u ^ rgbaColor; // Assumes alpha is in the rightmost byte, change as needed
}
korona_257310

Invert the bits of each component separately:

Color InvertMeAColour(Color ColourToInvert)
{
   return Color.FromArgb((byte)~ColourToInvert.R, (byte)~ColourToInvert.G, (byte)~ColourToInvert.B);
}

EDIT: The ~ operator does not work with bytes automatically, cast is needed.

user_1331430

What you already have is an RGB-Invert. There are other ways to classify colors and hence other definitions for the Inverse of a Color.

But it sounds like maybe you want a contrasting Color, and there isn't a simple Inversion that is going to work for all colors including RGB(127, 127, 127).

What you need is 1) a conversion to HSV (see ThibThibs answer) and invert the Hue, but also 2) check if the Hue isn't to close to the middle and if so go to either fully bright or fully dark.

user_607610

I've created this simple function for VB.NET:

Public Shared Function Invert(ByVal Culoare As Color) As Color
    Return Color.FromArgb(Culoare.ToArgb() Xor &HFFFFFF)
End Function

And this one for C#:

public static Color Invert(Color Culoare)
{
    return Color.FromArgb(Culoare.ToArgb() ^ 0xFFFFFF);
}
user_102938350
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