Hi Gert,

Gert Cuykens wrote:

what is the difference between brightness and saturation ?

saturation is a measure of how vivid a colour is, brightness is a measure of its brightness :) so a deep green would be both dark and saturated, whereas a light leaf green is perhaps not so saturated, and brighter.

To see the difference, use the color picker in HSV mode, and change the S and V sliders independently (Value and Brightness are very closely related).

Cheers, Dave.

No, hue means shade of color. Green, red, blue, etc.

-----Original Message----- From: gimp-user-bounces@lists.xcf.berkeley.edu [mailto:gimp-user-bounces@lists.xcf.berkeley.edu] On Behalf Of Gert Cuykens Sent: Thursday, December 09, 2004 5:18 PM To: David Neary
Cc: gimp-user@lists.xcf.berkeley.edu Subject: Re: [Gimp-user] difference between brightness and saturation

On Thu, 9 Dec 2004 23:07:25 +0100, David Neary wrote:

Hi Gert,

Gert Cuykens wrote:

what is the difference between brightness and saturation ?

saturation is a measure of how vivid a colour is, brightness is a measure of its brightness :) so a deep green would be both dark and saturated, whereas a light leaf green is perhaps not so saturated, and brighter.

To see the difference, use the color picker in HSV mode, and change the S and V sliders independently (Value and Brightness are very closely related).

Cheers, Dave.

--
David Neary,
Lyon, France
E-Mail: bolsh@gimp.org
CV: http://dneary.free.fr/CV/

thx

What does contrast and lightness do then ? Hue mean sunglasses right ?

On Friday, December 10, 2004 11:39 AM [GMT+1=CET], Gert Cuykens wrote:

can someone make a little help dictionary on the gimp site because when i read hue i think of a cow that says something :)

How about this:
http://docs.gimp.org/en/go01.html

Bob Long

http://docs.gimp.org/en/go01.html

yep looks very nice except it need some more words for example hue only shows two pictures. Can someone at the circle comment to the documentation please.

IMO these docs explain what hue actually is - though they could use some more links (HSV and Hue should be in section H, and link to their explanation in "Color"). And the images should be given numbers and be referenced explicitely.

Maybe you could point out how exactly

"Hue: It's the color itself, resulting from the combination of primary colors. All color shades (except greylevels) are represented in a chromatic circle: Yellow, Blue, and also purple, orange... It goes from 0° to 360°. ("Color" term is often used instead of "Hue". RGB colors are "Primary colors")."

should be changed?

HTH, Michael

Hi,

Gert Cuykens writes:

http://docs.gimp.org/en/go01.html

yep looks very nice except it need some more words for example hue only shows two pictures. Can someone at the circle comment to the documentation please.

If you think the docs need improvements, feel free to join the gimp-docs team. The manual is in CVS (module gimp-help-2) and there's a mailing-list (gimp-docs).

Sven

On Sat, Dec 11, 2004 at 11:33:40PM +0100, Gert Cuykens wrote:

who do i ask if they would like to change the word lightness into brightness from the gimp gui?

without taking the time to look it up, there is a chance that these definitions pre-date computers. much of the imaging language came from photographic techniques and laboratory color measuring and algorythms that describe the differences in colors.

i have a similar story. i wanted to yell at the designer of the XServer for choosing Red, Green and Blue for the display colors. my public schooling thoroughly trained me in Red Yellow and Blue. i did yell at him, actually. he kindly typed back that this RGB thing occured in 1910 or so, about the same time they were inventing sushi and thinking about having a world war now that the world knew about each other better or something.

it is all fairly crazy. to me, it is a wonder that anything works.

carol

On Sat, 11 Dec 2004, Gert Cuykens wrote:

who do i ask if they would like to change the word lightness into brightness from the gimp gui?

You don't to ask anyone, being an open source project, you can do it your self

I found these files that had "Lightness" which you could try changing to "Brightness"

gimpcolorizetool.c: gimphuesaturationtool.c: hue-saturation.c
gimpcolorspace.c

Owen

Gert Cuykens (gert.cuykens@gmail.com) wrote:

who do i ask if they would like to change the word lightness into brightness from the gimp gui?

"Brightness is the perceived intensity of light coming from the image itself, rather than any property of the portrayed scene. Brightness is sometimes defined as perceived luminance. (From Adelson, MIT)"

and

"Lightness is the perceived reflectance of a surface. It represents the visual system's attempt to extract reflectance based on the luminances in the scene. (From Adelson, MIT)"

So your implied assumption that Brightness and Lightness are exchangeable terms is simply wrong. You were quite unspecific where you want to exchange these terms and I cannot determine if the usage of "lightness" is correct or not. My guess is, that somebody put some thought in the choice of words and I wouldn't change it unless someone shows that the usage of "lightness" is wrong.

Bye, Simon

Hi,

Gert Cuykens writes:

who do i ask if they would like to change the word lightness into brightness from the gimp gui?

You could read up on the differences. A good source is the Color FAQ maintained by Charles Poynton.

Sven

Hi,

Gert Cuykens wrote:

i did not assume anything one of the reply's said it was :)

Apologies - I was simplifying things - perhaps too much. Both are directly related to luminance (which is often called lightness). I had the impression that you were something of a beginner, and did not want to overburden you with technical terms.

And quite honestly, while I knew taht there was some difference between the terms, I would not have been able to tell you what it was :)

Cheers,
Dave.

Carol Spears wrote:

i have a similar story. i wanted to yell at the designer of the XServer for choosing Red, Green and Blue for the display colors. my public schooling thoroughly trained me in Red Yellow and Blue.

RGB is for additive color mixing, like what happens in CRT and LCD displays.

Red, Yellow and Blue is probably used in the context of subtractive color mixing, like what happens with ink printed on paper or when mixing paint. The colors used for subtractive mixing are actualle cyan, magenta and yellow (the exact opposites of red, green and blue). But in mixing paint or similar, the color that is used for magenta is quite close to red, and the color that is used for cyan is quite close to blue.