How the Color Management works in InDesign?

[Ashu24845488rcnx]

Please tell me about the InDesign Color Management. 

How the color is transforming.

How RGB color value calculations are done.

Whether the given color value is changed?

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[Frans v.d. Geest]

It all depends on your RGB source profile setting and your CMYK output profile setting, it is calculated by translating to LAB and from LAB to the output gamut, and rendering intent in that profile.

[Ashu24845488rcnx]

Okay, thank you.
So whether it consider the color profile of monitor while displaying final output color?

Can you please provide the calculation part of the color transformaton.

[rob day]

All color is converted into your system's RGB Monitor profile for display. The device independent Lab space is used to make the translatiion.

So if your document has Coated GRACoL as its CMYK assignment, and ProPhoto RGB as its RGB assignment, displayed CMYK color is a conversion from GRACoL>Lab>Monitor RGB, and displayed RGB color is a conversion from ProPhoto>Lab>Monitor RGB.

In both cases there are probably some colors that are outside of the Monitor RGB gamut depending on the monitor's capabilities, so the out-of-gamut color gets clipped.

[Ashu24845488rcnx]

okay, but i'm confused about the conversion that you have mentioned.
So can you please explain briefly and provide conversion code.

[rob day]

So can you please explain briefly and provide conversion code.

I think the math/code for Adobe color conversions is not open source and is proprietary. Maybe explain what you are trying to do?

Color spaces can be shown as a 3D model—Apple’s ColorSync Utility can display and compare color spaces. For example this is my Monitor RGB space:

I can compare it with a different space—here’s the comparison to Coated GRACoL CMYK. You can see most of, but no all of, the GRACoL space can be displayed. Some of the cyan/green spectrum is outside of my display’s gamut. The color management system brings the out-of-gamut color into the Monitor RGB gamut—the out-of-gamut cyans and greens get "clipped". The chosen Conversion Intent (Relative, Perceptual, Absolute, or Saturation) is used to determine how out-of-gamut colors are brought into the destination gamut.

The Lab space is an abstract representation of all visible color—it’s not tied to any device. It’s used to make the translation between device dependent  spaces. You can see my Monitor RGB space (as well as Coated GRACoL CMYK) are completely inside of the Lab space:

[rob day]

provide conversion code

You can use JavaScript to get and set color conversions in Photoshop or InDesign. As an example this thread links to a JavaScript that will get color managed RGB and CMYK  process color conversions for Pantone solid ink Lab colors:

https://community.adobe.com/t5/indesign-discussions/branding-color-guide/td-p/10818696

[Ashu24845488rcnx]

Thanks @rob day  for your explaination.

[Ashu24845488rcnx]

Can you please explain the conversion process of RGB color if i apply tint and opacity.

[rob day]

Hi @Ashu24845488rcnx , Opacity is a transparency effect while Tint is an opaque color with a simple percentage adjustment of the starting RGB values.

For example if you apply a 50% tint to an RGB color, the Color panel will show the RGB values of the tinted version. Here the starting RGB values are 100|255|0 and the 50% Tint value is 178|255|128. The adjusted RGB values are a percentage change where sv is the starting value and t is the tint percentage: 255–((255–sv) x (t/100)). With CMYK colors where the scale is 0–100, the formula is simply sv*(t/100)

The appearance of the tinted or untinted RGB colors depends on the RGB profile assignment:

Opacity is considerably more complex because the document’s Transparency Blend Space comes into play. InDesign lets you mix objects with different color modes on the same page, so there has to be a single blending space chosen for when the transparency effects are flattened for final output or export.

If the Transparency Blend Space is set to Document CMYK, the page is previewed as the RGB colors would output in the document’s assigned CMYK space—the RGB colors are not actually converted to CMYK, but you get a CMYK soft proof of the future RGB color conversion to CMYK:

If the chosen Blend Space is Document RGB, the transparency effects are soft proofed in the document’s assigned RGB profile. An RGB blend space would be useful when you are exporting to a flattened image format like JPEG for web or screen destinations:

[Ashu24845488rcnx]

Thanks @rob day 

[Ashu24845488rcnx]

Hi @rob day 
I have small doubt about the formula you mentioned above "255–((255–sv) x (t/100))".
Whether this formula works for all the color? (like outOfGamut color)

[rob day]

The example I'm showing above is out of gamut. Keep in mind that if there is any transparent object on the spread, the chosen transparency blend space is invoked for the preview. The tint formula only gets the the percentage of an RGB color when the scale is from 0 (black) to 255 (white)--there's no color space conversion.

[Ashu24845488rcnx]

Hi @rob day , Is there any calculation for the CMYK and RGB Transparency Blend Space?

[rob day]

Is there any calculation for the CMYK and RGB Transparency Blend Space?

It would be either Document RGB (the assigned RGB profile) or Document CMYK (the assigned CMYK profile). The actual color does not change, but the displayed soft proof does.

The soft proof is color managed—when there is a transparent object on the spread, and the blend mode is CMYK, the display of RGB fills would be Document RGB>Lab>Document CMYK>Lab>MonitorRGB. The color managed soft proof does not change the actual RGB fill values:

Also, by default the Color Settings’ Conversion Option Intent handles how color is brought into gamut and could affect the display of an RGB color in the CMYK blend space..

Or, the Color Settings’ Intent can be overidden in the Assign Profiles... dialog:

[Ashu24845488rcnx]

Okay, Thank u @rob day 

[good_glamour11186]

Hi @rob day  
What is the conversion steps if the applied color is CMYK with 50% opacity and Transparency Blend Space is "Document RGB".
Can you please explain.

[rob day]

Hi @Ashu24845488rcnx , InDesign documents can have a mix of RGB, CMYK, or Lab native colors or swatches. Every document has an assigned RGB and CMYK .icc profile, which handle the color appearance of specified RGB or CMYK values. If the document has no assigned profiles, the fall back is to the Color Settings’ Working Spaces.

If you convert a native color or swatch from RGB to CMYK, or CMYK to RGB, the assigned document profiles are used as the source and destination for the color conversion.

[Brad @ Roaring Mouse]

Color management is a complicated subject, but if you are new to it, it's best to look at it through the analogy of boxes of crayons. Each color space/device can be looked at as being a different box of crayons. Some spaces have more crayons in the box. Some have less. Say RGB is a 64box and CMYK is a 24box. There will be more shades of certain colours in the 64box than in the 24box, so when you are converting from a 64box to a 24box, that same red you might have used from the 64box isn't available in the 24box, so it finds the closest matching red ... this unavoidably cause a shift in some colours that just don't exist in a 24box. How this conversion is done in the digital world is that every colour can be measured in the LAB color space, so Color Management in any any product uses those LAB numbers to find the closest match. Also, your monitor also has its own number of crayons, so even displaying any of these colors requires a bit of conversion, although this is just for your monitor and doesn't change you images in a any way.

In the old days, anything people were printing on an offset press used similar CMYK inks, so it was a common adage to pre-convert any RGB images to CMYK. Nowadays, however, there are so many different types of CMYK printers (and beyond, e.g a 12-ink Inkjet) that have very different colour responses, hence, each device has its own box of crayons, so its best to leave your images as RGB, and let Color Mangement deal with converting to the specific color space of your final output device for best results.

[Ashu24845488rcnx]

Thanks Brad @ Roaring Mouse.

If i apply RGB color to rectangle shape in InDesign, how the final output color will be display in the monitor?
Please explain the color transformation procedure that will be performed before color displaying on the monitor.

[Brad @ Roaring Mouse · Accepted solution]

There's no simple "conversion code", so if you're looking for a simple mathematical equation, there is none. I suggest you truly need to study Color Management. You can find lots of info in the Internet about the subject. Start there... as much as we're here to help, we are not here to provide you an entire free education. But here goes...

Color Management can be done in many places, it's not just in InDesign or whatever particular app you are using. It can also be at the System level. e.g a Mac has ColorSync.  No matter which is used though, they are all very complex software infrastructure that utilise ICC Profiles to convert colors from one device to another, that when properly installed and selected, can help maintain color consistency.

Back to its simplest concepts though, they are all using the set of data in each ICC Profile as a "look-up table" that have been carefully measured using a very accurate device called a spectrophotometer. e.g. an offset press will print out a very detailed sheet of hundreds of squares of colors on a particular type of paper, and these are all measured and stored in a file for that specific press for that specific paper: its ICC Profile.

Your monitor, when it was manufactured, will also be similarly measured and all the colors it can display are carefully recorded and stored in a specific ICC Profile for it, and is usually installed by your computer when you connect the monitor. Yes, there will be adjustments you will need to do, some are automatic some are manual, e.g. say if you turn the brightness down on your monitor, that chnages how its going to be displayed, so most computer systems have simple calibration utilities to make a revised ICC profiles for your monitor's current state. (High end professionals will employ a calibration device/spectrophotometer to measure their monitor even more accurately).

So to answer this one SPECIFIC question... "If i apply RGB color to rectangle shape in InDesign, how the final output color will be display in the monitor?

InDesign has its Color Settings (under the Edit menu) and what you have set there determines how colors are handled. In many cases the default for RGB in these settings is to a standard sRGB ICC, which is roughly equivalent to most monitors, but never exact. So, if you draw a box with pure Red in RGB (that would be 100R 0G 0B), InDesign passes that value to your computer system, which will then send it to your monitor and will "look-up" in the Monitor's specific ICC profile what values it needs to use to display that Red accurately to YOU. By the time it gets to the monitor it may be that it needs to uses the values 98R 3G 4B to match the Red in your document instead of 100R 0G 0B.

This in NO way changes the Red value in your Document; This is only for display purposes.

However, if you were to PRINT this Document, say to a typical CMYK-based press, InDesign will look up the printer's specific ICC profile (in ID's Color settings you might see a CMYK setting of e.g "SWOP Offset Coated" for an old-school offset press) and finds what it needs to send to the printer in CMYK to match your red as closely as possible. It may find that the closest match to your Red is 2C 92M 99Y 2K. While this "2C 92M 99Y 2K" will look fine on a standard offset press on the right paper. it will look completely wrong if sent to a completely different printer and paper, say an inkjet printer on gloss photo paper, you would need to make sure you have selected the right Profile for your intended output. 

What this all comes down to, is why exactly are you asking for a specfic "conversion code"?

We've already repeatedly explained the concepts to you, but you still continue to ask the same unanswerable question. It would help to know what your end goal here is.

[Ashu24845488rcnx]

Okay, Thank you.