[Gimp-user] value invert is for luminance only, or can be also other thing ?

[Sven Neumann]

Hi,

On Tue, 2008-06-10 at 18:46 +0300, Cristian Secară wrote:
> In Colors menu there are two invert positions, one is Invert and other
> in Value invert.
> 
> For the first invert, the floating help says "Invert the colors".
> For the second invert, the floatig help says "Invert the brightness of
> each pixel".
> 
> My first question is why are the menu names not self-explained.
> Why is the first only "Invert" and is not "Color invert" ?

Because "Invert" implements the classic definition of an Invert
operation on RGB images. It's the term that people are looking for. 

> My second question is what other value things can be inverted other
> than the luminance pixels. Why is the second "Value invert" and not
> "Luminance invert" ? Whom else value ?

Value is a well-defined concept in image processing. The value of a
pixel is defined as the maximum value of its RGB channels. It one way to
define a measure for the intensity of a pixel. The Value Invert
operation performs the color inversion in the HSV space (where V is
Value), leaving Hue and Saturation untouched.


Sven