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Sonia5FC1
Participant
May 13, 2022
Answered

Cohérence couleur - valeur hexadecimal

  • May 13, 2022
  • 1 reply
  • 568 views

Bonjour ! 

Je ne sais pas si vous pourrez m'aider, mais je ne sais pas pourquoi une même valeur hexadecimale ne rend pas (pour moi ^^) les même valeurs CMJN dans Photoshop que dans Indesign+Illustrator. 

J'ai pourtant utilisé Bridge pour synchroniser l'espace colorimétrique 😞 

Alors, j'avoue ne plus savoir où chercher, je n'ai pas souvenir d'avoir eu le soucis auparavent. 

 

Valeur hexa : #29B8CE

Dans Illustrator + Indesign : 

C : 70 M : 0 J : 20 N : 0 

Dans Photoshop : 

C : 70 M : 1 J : 20 N : 0 

Je sais que la différence est minime mais si je la "corrige", j'obtiens une autre valeur hexa : #2ab9ce.

 

Est- ce que quelqu'un aurait une idée ? 

Je précise que les versions de chacun des logiciels sont à jour et que si je vais dans les formats d'epreuve de chaque logiciel je suis bien en cmjn + j'ai bien créé mes documents en espace de travail cmjn à la base. 

 

Merci pour tout et bonne journée !

Sonia

This topic has been closed for replies.
Correct answer D Fosse

Hexadecimal numbers are not absolute, despite what most people think. They are just base 16 notation for standard RGB numbers.

 

Numbers are relative to color space.

 

This means that the same color will yield different numbers in different color spaces. And any given set of numbers will produce different colors. Note the hex numbers here:

 

The same goes for CMYK. US Web Coated (SWOP) is not the same as, say, Coated FOGRA39. The numbers will be different.

 

So you always need to know which specific color space you are dealing with. There is no need to synchronise color settings in Bridge, but you need to keep track of the document color spaces and know what they are. If you want consistency, you can only get that within a certain color space.

 

If you want an absolute reference, use Lab numbers. That's the reference for all color management:

 

There is also the matter of gamut clipping, which can easily happen in RGB > CMYK because the latter usually has a much more restricted gamut. That's just the limitations of the inks used in offset printing.

1 reply

D Fosse
Community Expert
D FosseCommunity ExpertCorrect answer
Community Expert
May 13, 2022

Hexadecimal numbers are not absolute, despite what most people think. They are just base 16 notation for standard RGB numbers.

 

Numbers are relative to color space.

 

This means that the same color will yield different numbers in different color spaces. And any given set of numbers will produce different colors. Note the hex numbers here:

 

The same goes for CMYK. US Web Coated (SWOP) is not the same as, say, Coated FOGRA39. The numbers will be different.

 

So you always need to know which specific color space you are dealing with. There is no need to synchronise color settings in Bridge, but you need to keep track of the document color spaces and know what they are. If you want consistency, you can only get that within a certain color space.

 

If you want an absolute reference, use Lab numbers. That's the reference for all color management:

 

There is also the matter of gamut clipping, which can easily happen in RGB > CMYK because the latter usually has a much more restricted gamut. That's just the limitations of the inks used in offset printing.

    S
    Sonia5FC1Author
    Participant
    May 13, 2022

    Thank you so much for all these information !

    I'll use the LAB datas in this case (seems easier ^^ and have the adding value to be identical ! ).

    I wish you a very good day, 

    Sonia 

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