What's the difference between choosing "Assign" or "Convert" when changing color space from RGB to CMYK?

[LogosByDim]

Hi there everybody, thanks for tuning in.

I've been working with a document created using a template for the web, whcih automatically assigns a sRGB color profile. Now, just for example, if I want to switch the color mode from sRGB to CMYK I see I have two options: one called "Assign" and the other, which is default by the way, called "Convert". I do understand the different gamuts between RGB and CMYK and that converting from the first to the last may produce dull shades to the colors. What I do NOT understand is what the difference is between ASSIGN and CONVERT in the Document Setup Menu under Color. One thing I've noticed is that Converting the colors do make a change to the color sliders, whereas assigning the color mode doesn't. Can someone explain how theese two features work in detail and preferably in a context for printing? Thank you so much for your help in advance!

Dimitar Z.

[Fixx]

1 hour ago, LogosByDim said:

if I want to switch the color mode from sRGB to CMYK I see I have two options: one called "Assign" and the other, which is default by the way, called "Convert".

If you try to move from RGB to CMYK you will notice the Assign/Convert choice is greyed out. Moving from one colour space to another is always converting.

Changing colour profile can be done either as Convert or Assign. If colour management is working right you will want to use Convert. Assign is for unmanaged files (no profile assigned), or if you know image has wrong profile attached.

[LogosByDim]

29 minutes ago, Fixx said:

If you try to move from RGB to CMYK you will notice the Assign/Convert choice is greyed out. Moving from one colour space to another is always converting.

Changing colour profile can be done either as Convert or Assign. If colour management is working right you will want to use Convert. Assign is for unmanaged files (no profile assigned), or if you know image has wrong profile attached.

Thank you Fixx for the great explanation, that is exactly what I was looking for. You answered my question perfectly. Please have a nice day ahead and keep solving problems like mine. Helps a lot!

[Lorox]

On 11/17/2020 at 9:18 AM, Fixx said:

If you try to move from RGB to CMYK you will notice the Assign/Convert choice is greyed out. Moving from one colour space to another is always converting.

Changing colour profile can be done either as Convert or Assign. If colour management is working right you will want to use Convert. Assign is for unmanaged files (no profile assigned), or if you know image has wrong profile attached.

Yeah, I think it's obvious that when you go from RGB to CMYK (or vice versa) there must be a conversion.

When going from one CMYK profile (say Fogra27) to another (say ISOcoated_v2) you sort of can decide whether the colours already there in the document should maintain their given CYMK values ( > Assign) or if the colour's appearance should be encoded according to the values the new target CMYK profile considers appropriate ( > Convert).

However, I've encountered some recurring difficulties regarding colour profiles myself and I'm not sure what to finally think about it...

 

[LogosByDim]

2 hours ago, Lorox said:

When going from one CMYK profile (say Fogra27) to another (say ISOcoated_v2) you sort of can decide whether the colours already there in the document should maintain their given CYMK values ( > Assign) or if the colour's appearance should be encoded according to the values the new target CMYK profile considers appropriate ( > Convert).

Hi Lorox, thank you for the explanation. I did see the "assign" and "convert" buttons were grayed out when switching from RGB to CMYK (color spaces), only after I posted the question. In this case it is always a conversion.

So the main difference is essentially when changing from one color profile to another, as you said? Why would I choose assign instead of convert? Let's take this for example.

I'm working on a logo in Affinity Designer using the RGB color space and the sRGB color profile. For some reason, I'd like to change the color profile to Adobe RGB, because it covers a wider color gamut. In this case, assigning or converting the color values wouldn't make any bad impact on the design, I assume, since the Adobe RGB profile already covers the sRGB color profile.

Now. If I was working in Adobe RGB in the first place, and then later on wished to change to sRGB, I'll have to options: Either choose "convert" so that the color values used in the document change in order to fit inside the color gamut that is covered by sRGB. Or, only "assign" the new color profile from Adobe RGB to sRGB without having a change to the color values. This case is unrealistic though, as I understand it, because the colors that were from Adobe RGB and outside the new sRGB color profile aren't being covered in sRGB, despite the fact that I "assigned" the color space, or rather embedded it in the document.

This perhaps could lead to problems I assume? Since the colors that were originally used in the first Adobe RGB color profile aren't covered in the newly "assigned" sRGB profile.

Am I right on this or did I misunderstand something? Perhaps the assign feature is used in a different case or situation?

Thank you for reading!

[Chris26]

On 11/20/2020 at 4:13 PM, LogosByDim said:

So the main difference is essentially when changing from one color profile to another, as you said? Why would I choose assign instead of convert?

Let's make this less complicated.  CONVERT: Maintains the exact colours that you have in your image but gives them new numbers based upon the colour profile of the target output. ASSIGN:  You preserve the colour numbers, but the new profile you have assigned will change the colours drastically.

To put it another way:  Colour 120 120 120 is an almost neutral gray.  If I convert this colour then I maybe reading these numbers: - 125 125 125, BUT the exact same neutral gray will be seen in the image.  If I choose assign, 120 120 120, then I will maintain these exact same numbers in the new image document BUT the colour will no longer be an almost gray. It may become a darkened gray.  this is just a simple summary, I hope something here helps to clarify.

If you would like a more detailed clarification then I recommend this :  https://ninedegreesbelow.com/photography/convert-assign.html

[LogosByDim]

1 hour ago, Chris26 said:

Let's make this less complicated.  CONVERT: Maintains the exact colours that you have in your image but gives them new numbers based upon the colour profile of the target output. ASSIGN:  You preserve the colour numbers, but the new profile you have assigned will change the colours drastically.

Hey Chris, thanks a lot for simplifying my unclarity, I appreciate it. After seeing your answer and reading through the whole article you attached, I truly understood the whole thing so much easier. Everything is clear for me now.

If someone reading this topic has the same question as I had, I advise you to read the article attached in the answer given by Chris26. It is very well written.

Thank you everyone for your answers!

- Dimitar

[Chris26]

5 minutes ago, LogosByDim said:

Hey Chris, thanks a lot for simplifying my unclarity, I appreciate it. After seeing your answer and reading through the whole article you attached, I truly understood the whole thing so much easier. Everything is clear for me now.

If someone reading this topic has the same question as I had, I advise you to read the article attached in the answer given by Chris26. It is very well written.

Thank you everyone for your answers!

- Dimitar

You are very welcome

[Lorox]

I guess Chris26 (and the article he'd referred to) made the topic relatively clear and understandable – at least as we're talking about RGB colour mode. This given, I'd think this will be useful predominantly for photographers whereas converting from RGB to CMYK (and possibly from one CMYK profile to another) will be important to designers doing work that is bound to be commercially printed using e.g. offset printing.

In this area it might be crucial that certain colours will not be changed at all and be printed with the exact CMYK values which had initially been assigned to them (e.g. for some corporate design or house style) whereas colours in pictures (RBG and/or CMYK) placed in the design actually should be converted to fit the actual printing process/workflow and thus appear – visually – unchanged in the end (while in fact their colour numbers/values have been more or less altered in the process).

It can actually get a bit complicated when a proper prepress workflow is concerned. In this respect Affinity Publisher has given me some headaches recently as black text/type – which in CMYK printing should normally be just 100% black (with no C, M or Y in it) – had turned out to be a mix of all the four components of CMYK in the PDF meant for sending to the printer's shop. It could be corrected in the end, but one has to double check and be quite careful – mistakes can happen easily as it seems.

[LogosByDim]

Yes @Lorox, I do agree with all that you said. In fact, color management for printing of logos was my main concern on this topic.

When I design a logo for an individual it usually goes only with an RGB color space format. But when a client is seeking to print the logo I need to prepare a CMYK version as well, of all the files. Sometimes also a spot color, PANTONE version.

Since RGB has a broader color gamut than CMYK, isn't it wiser to begin the design in RGB and then convert to CMYK?

Some people suggest the opposite, to start off with CMYK and then convert to what is needed. That way you're always sure the colors you choose will be suitable for printing.

But isn't it a strange to start off with a smaller color gamut? To get those nicely saturated colors in RGB later on would require a lot of changes to colors if one begins with CMYK.

Anyways, this is more than out of point for this topic. Thanks to everyone for the answers and I think all my questions are solved. 🙂

[Slammer]

23 hours ago, LogosByDim said:

Now. If I was working in Adobe RGB in the first place, and then later on wished to change to sRGB, I'll have to options: Either choose "convert" so that the color values used in the document change in order to fit inside the color gamut that is covered by sRGB. Or, only "assign" the new color profile from Adobe RGB to sRGB without having a change to the color values. This case is unrealistic though, as I understand it, because the colors that were from Adobe RGB and outside the new sRGB color profile aren't being covered in sRGB, despite the fact that I "assigned" the color space, or rather embedded it in the document.

Just imagine you are going down a one way street where every step you take will diminish your color gamut, going from a low gamut profile to a high gamut profile won´t magically increase your gamut and in this case your adobe RGB has the wider gamut over the sRGB.

This goes all the way down to CMYK which has the smallest gamut and there is no coming back from there.

[Chris26]

8 minutes ago, Slammer said:

Just imagine you are going down a one way street where every step you take will diminish your color gamut, going from a low gamut profile to a high gamut profile won´t magically increase your gamut and in this case your adobe RGB has the wider gamut over the sRGB.

Hi Slammer, well I recognise this is going off the OP's original question since he has his answer now, but, Yep, just to throw a spanner in the works, I have read a few times about these two colour spaces and decided to dig up something of Practical Interest to anyone who is interested and that is that Adobe RGB's wider colour gamut comes with a few exceptions and here they are:  There are more detailed explanations as to what is going on under the hood, but simply put.......

Quoted from  https://www.cambridgeincolour.com/tutorials/srgb-adobergb1998.htm

 Ask yourself: do you really need the richer cyan-green midtones, orange-magenta highlights, or green shadows? Will these colors also be visible in the final print? Will these differences even be noticeable? If you've answered "no" to any of these questions, then you would be better served using sRGB. sRGB will make the most of your bit depth because it allocates more bits to encoding the colors present in your image

 

[Slammer]

5 hours ago, Chris26 said:

Hi Slammer, well I recognise this is going off the OP's original question since he has his answer now, but, Yep, just to throw a spanner in the works, I have read a few times about these two colour spaces and decided to dig up something of Practical Interest to anyone who is interested and that is that Adobe RGB's wider colour gamut comes with a few exceptions and here they are:  There are more detailed explanations as to what is going on under the hood, but simply put.......

Quoted from  https://www.cambridgeincolour.com/tutorials/srgb-adobergb1998.htm

 Ask yourself: do you really need the richer cyan-green midtones, orange-magenta highlights, or green shadows? Will these colors also be visible in the final print? Will these differences even be noticeable? If you've answered "no" to any of these questions, then you would be better served using sRGB. sRGB will make the most of your bit depth because it allocates more bits to encoding the colors present in your image

 

Interesting, I alway love reading about the nitty-gritty aspects of color management, I suppose that the question of colour balance is a case of how the profile sets the white point. In today´s printing, especially offset printing, wide gamut CMYK is very much a thing, even more so in flexographic I would wager.
However what I have noticed is that adobe RGB performs better after inRIP conversion to a generic CMKY profile on press than sRGB does. Having said that I do think that it could be an issue that in Europe denstitometers are set to Status "E" and in the US they are on Status "T" and that gives you a complete different whitepoint.

It´s one of the reasons, that prints done in the US with Euroscale profiles tend to have issues, same with a EU printer using SWOP in combination with status T.

[LogosByDim]

Morning! I see that @Slammer and @Chris26 both have some pretty interesting opinions. Thanks for all the input, despite that it went a little off the road, but I also like to get in to details when it comes to color management.

What would you think: Is it better to start off designing a vector drawing in sRGB, then convert the final work to CMYK for a printable version. Or start off in CMYK and then convert to RGB?

Let's say the above example is related to a logo design in vector, aimed to be used for both a website (RGB for screens) and offset printing (CMYK). What would you do?

[Chris26]

2 hours ago, LogosByDim said:

Morning! I see that @Slammer and @Chris26 both have some pretty interesting opinions. Thanks for all the input, despite that it went a little off the road, but I also like to get in to details when it comes to color management.

What would you think: Is it better to start off designing a vector drawing in sRGB, then convert the final work to CMYK for a printable version. Or start off in CMYK and then convert to RGB?

Let's say the above example is related to a logo design in vector, aimed to be used for both a website (RGB for screens) and offset printing (CMYK). What would you do?

I actually.for the first time in my years as a photographer, am having to design a logo and branch into design, so I am not very experienced at all when it comes to this subject about different CMYK things and exporting stuff to pdf with all the problems I have read about rich blacks, poor blacks, and any other non black issues that are supposed to be black🙄, as I have much to learn.  But my instincts tell me to start all designing in sRGB.  Then I will soft proof that in the CMYK profile of the out-sourced printer I choose (if printing myself on my laser then I would of course stay in sRGB and have no need for any converting), then I will adjust the necessary colour according to the soft proof and send that to the out-sourced printer.  Logic here is to do all designing in s'RGB since it would be harder to have a cmyk image and then adjust for output on your own printer or even moreso for an out-sourced printer.  But I would be glad to hear from others on this issue.

[LogosByDim]

55 minutes ago, Chris26 said:

But my instincts tell me to start all designing in sRGB

The first that came to my mind was also to start off in sRGB and then convert to CMYK if needed for print, and make the necessary adjusments so the colors look almost the same after the conversion. But most articles I've read regarding this question say that it's wiser to start off with CMYK because the conversion to RGB later on won't have that big color shift (difference), and you may not even need to adjust anything after converting. I believe this sounds pretty logical. 

It's interesting to hear that you're trying out something new @Chris26. I've been into the creation of logos for while and that's what got me concerned about color management in the first place.
And hey! If you would need any help with your logo I'd be glad to help you out. That would be lots of fun. You can send me a direct message by clicking here.

Anyways, thanks for the opinion!

[Chris26]

15 minutes ago, BofG said:

I'd go sRGB and put a soft proof on from the get go.

The thing is that CMYK on a screen looks worse than it does on real paper output. You don't get the same reflectance, diffusion etc. so it always looks "flatter" on screen. If you opt for a CMYK document, then you straight away compromise whatever you produce for use on screen, if you go for RGB then at least you are fully in control of the compromises that are made between screen and print.

Yes I agree with that, and as a side note the only real value in soft proofing an RGB image in a CMYK profile is that you can see exactly, with great precision, which colours and tones may not print.  Brightness levels are harder to determine, but as a general rule of thumb I always tweak a global brightness adjustment upwards and this has proved generally pleasing.

[Lorox]

6 hours ago, LogosByDim said:

Morning! I see that @Slammer and @Chris26 both have some pretty interesting opinions. Thanks for all the input, despite that it went a little off the road, but I also like to get in to details when it comes to color management.

What would you think: Is it better to start off designing a vector drawing in sRGB, then convert the final work to CMYK for a printable version. Or start off in CMYK and then convert to RGB?

Let's say the above example is related to a logo design in vector, aimed to be used for both a website (RGB for screens) and offset printing (CMYK). What would you do?

If I may contribute something from my angle as a graphic designer working mainly for print:

I personally very much prefer or suggest starting from CMYK (if not black and white only) when designing a logo. Starting from CMYK ensures that the logo will be printable by offset printing quite exactly the way it has been seen on screen before (given, of course, that the system/display is more or less calibrated).

As the CMYK colour space is considerably smaller than the common RGB colour spaces, the logo begun in CMYK should be easily reproduceable on screen once it has been converted to RGB as there are almost no colours in CMYK that cannot be closely reproduced in RGB. Given that the vast majority of displays in use will not even be able to truly display any RGB colour space bigger than sRGB it seems reasonable or sufficient to me to produce an RGB-version of the initial CMYK-logo using just that sRGB colour space.

There may be exceptions, however, if you consciously and decidedly design for screen only and really want to push one or the other other colour for that vibrant (if not garish, posibly...) highly saturated, almost neon colour look as it is possible in RGB with some hues.
These sort of colours just cannot survive in CYMK, though. So you'll lose them and will be forced to accept considerably dulled versions of these after CMYK conversion, should the necessity arise at some time to have a print ready version nevertheless. Alternatively you might consider to create a version of your logo not using (just) CMYK but adding a suitable vibrant PANTONE spot colour (or even a fluorescent spot colour).

[v_kyr]

40 minutes ago, Lorox said:

As the CMYK colour space is considerably smaller than the common RGB colour spaces, the logo begun in CMYK should be easily reproduceable on screen once it has been converted to RGB as there are almost no colours in CMYK that cannot be closely reproduced in RGB. Given that the vast majority of displays in use will not even be able to truly display any RGB colour space bigger than sRGB it seems reasonable or sufficient to me to produce an RGB-version of the initial CMYK-logo using just that sRGB colour space.

[LogosByDim]

1 hour ago, BofG said:

I'd go sRGB and put a soft proof on from the get go.

The thing is that CMYK on a screen looks worse than it does on real paper output. You don't get the same reflectance, diffusion etc. so it always looks "flatter" on screen. If you opt for a CMYK document, then you straight away compromise whatever you produce for use on screen, if you go for RGB then at least you are fully in control of the compromises that are made between screen and print.

Thank you @BofG, I totally agree with the extra versatility when starting from sRGB, as long as one manages to keep the colors consistent when converting to smaller gamut color spaces later on - CMYK.

[LogosByDim]

45 minutes ago, Lorox said:

As the CMYK colour space is considerably smaller than the common RGB colour spaces, the logo begun in CMYK should be easily reproduceable on screen once it has been converted to RGB as there are almost no colours in CMYK that cannot be closely reproduced in RGB. Given that the vast majority of displays in use will not even be able to truly display any RGB colour space bigger than sRGB it seems reasonable or sufficient to me to produce an RGB-version of the initial CMYK-logo using just that sRGB colour space.

I truly agree with your opinion @Lorox. When we aim at consistency of the design while taking into consideration both print and digital screen mediums, I believe starting with CMYK would be the safest bet.

As you said, the exception being if the logo would initially be used only digitally, and then at a later point needs a printable version. The color shift will be greater here.

[Chris26]

1 hour ago, Lorox said:

I personally very much prefer or suggest starting from CMYK (if not black and white only) when designing a logo. Starting from CMYK ensures that the logo will be printable by offset printing quite exactly the way it has been seen on screen before (given, of course, that the system/display is more or less calibrated)

My obvious question mark banging up and down on the top of my nicely brushed and radiant hair as I read this was:  Exactly which of the myriad of cmyk profiles should one adopt when setting up one's document?   Should have added, assuming one is designing something but has no idea which priter one might be sending it to.

[LogosByDim]

7 minutes ago, Chris26 said:

Exactly which of the myriad of cmyk profiles should one adopt when setting up one's document?  

Upvote. Someone got an idea? The CMYK profiles are not few, as you all know.

My assumption is that when choosing which profile to use, when sending a file to a large print shop, consulting with the print shop on what profile would be most suitable for them would be the best. Perhaps one profile would produce a better result in the US, while a different profile for print shops in Europe. I think the standards are different.

[Fixx]

5 minutes ago, LogosByDim said:

Upvote. Someone got an idea? The CMYK profiles are not few, as you all know.

Common sense says use profiles your customer is going to use. You have to ask to what uses customer is going to put your design: letterhead, packaging cardboard, newspaper print etc... and probably supply a version for all those uses. The logo should look the same in all uses, or you have design a simplified version for lower quality printing methods.

[LogosByDim]

3 minutes ago, Fixx said:

Common sense says use profiles your customer is going to use.

I agree with that, Fixx.