CODEWITHSUNDEEP
iphoneobjective-cios
AndyC
AndyC

Reputation: 115

checking if a pixel is within a certain colour range

I have an iPhone app where you can select a pixel from an image and it will return the RGBA colour details.

I need to be able to determine if the selected pixel is within a certain range of colour e.g. a light or dark variation of a specific colour.

What would be the most efficient way of doing this?

Upvotes: 1

Views: 129

Answers (1)

Resh32
Resh32

Reputation: 6590

You will first have to convert your RGBA colorspace into HSBA (as suggested by @Zaph)

- (BOOL)getHue:(CGFloat *)hue saturation:(CGFloat *)saturation brightness:(CGFloat 
*)brightness alpha:(CGFloat *)alpha

Once you know the hue, saturation and brightness, you could define a "3D sphere" around a specific point. Hue is what defines the color, saturation is how vivid your color is (or grayed), and brightness is the amount of luminosity.

I would assume that you want a tight hue, and a loose saturation and brightness values, no need to look at alpha if you do not have transparency.

Upvotes: 3

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