histogrammes de couleur et RVB

[Taniere29]

Bonjour à tous,
dans le cadre d'un exposé sur les histogrammes, je suis confronté à une difficulté sur l'interprétation des histogrammes de couleur (R,V, et B).
L'histogramme d'une couleur exprime t'il la luminosité ou la saturation de la couleur (ou les deux)?
Quelles différences entre l'histogramme "couleur" et l'histogramme "RVB" comme dans photoshop par exemple?
merci de votre aide
Taniere

[Manfred M]

Let me do a quick Google Translate for the rest of the members:

Hi all in the context of a presentation on histograms, I am faced with a difficulty on the interpretation of color histograms (R, G, and B). Does the histogram of a color express the brightness or saturation of the color (or both)? What are the differences between the "color" histogram and the "RGB" histogram as in photoshop for example? thank you for your help

Taniere

[Donald]

I would just note that one of the 'rules' of the forum is that all communication must be in English. I know this seems very unfair to those whose first language is other than English, but for those people there are other fora available.

Donald
Moderator.

[Manfred M]

The R,G & B histogram is nothing more than a capture of the individual RGB channels, with the left side of the histogram representing the count of the darkest pure colours and the right side the lightest. The height of the histogram mere records the number of points in the image that have each value. The the RGB colour model saturation is intrinsically tied the the specific colour value, so effectively you are right, both brightness and saturation are melded together in what the histogram shows.

The RGB histogram is an amalgamation of all three colour histogram values into a single value, roughly based on how the human visual system interprets them; roughly 30%R, 60%G and 10%B.




L'histogramme R,V & B n'est rien de plus qu'une capture des canaux RVB individuels, le côté gauche de l'histogramme représentant le nombre des couleurs pures les plus sombres et le côté droit le plus clair. La hauteur de l'histogramme enregistre simplement le nombre de points de l'image qui ont chaque valeur. La saturation du modèle de couleur RVB est intrinsèquement liée à la valeur de couleur spécifique, donc effectivement vous avez raison, la luminosité et la saturation sont fusionnées dans ce que l'histogramme montre. L'histogramme RVB est un amalgame des trois valeurs de l'histogramme couleur en une seule valeur, à peu près basée sur la façon dont le système visuel humain les interprète; environ 30%R, 60%V et 10%B.

[Taniere29]

thank you Manfred M for this clarification.
and sorry for this first message in French.
Regards

[Cantab]

I would just note that one of the 'rules' of the forum is that all communication must be in English. I know this seems very unfair to those whose first language is other than English, but for those people there are other fora available.

Donald
Moderator.

Donald, I've just read your reference to the English rule -- a few minutes after I'd typed on another thread that messages could be in French but that there would be very limited communication if a message is not in English! It's a long time since I read the rules (assuming I did when I joined).

[DanK]

We have one person who routinely posts here in Portuguese, but he appears not to reply to any comments.

[lunaticitizen]

If only the forum software could automatically translate members' posts into our mother tongue, like Instagram does for example

[Acorn]

I suppose, Donald, it's bit like Gaelic and English and even Welsh. Thank heavens BBC Alba now has subtitles.

[xpatUSA]

I suppose, Donald, it's bit like Gaelic and English and even Welsh. Thank heavens BBC Alba now has subtitles.

Off topic but long ago on vacation in France, I learned that old folks from Wales and Normandy could understand each other's "native" tongue.