How to "best" convert Adobe RGB images to sRGB

[alexsalvatoretrotta]

Hi everyone!

I have a series of images that are original with Adobe RGB color profile, and my goal is to get them web compatible, then convert them all to sRGB.
I have a doubt about which is the best and correct method, to stay as faithful as possible to the native color profile (Adobe RGB).

What I am using for my workflow is:
I open the Adobe RGB image > Export > Save for Web > Embed Color Profile, Convert to sRGB.
This way the conversion should happen automatically during export.

The question is:
Would it be better to do the conversion BEFORE exporting?
Or is it just the same thing?

To convert first, I mean:
Open the Adobe RGB image > Edit > Convert to Profile (sRGB Profile ...) > Export > Save for Web > Embed Color Profile, Convert to sRGB.

I have looked at both images exported with the 2 methods, and they are visually identical, but reading the histogram data the data changes slightly.

Thank you!

[davescm]

The conversion uses the same colour engine whether you convert in Save for Web or in Edit > Convert to Profile.

However Convert to Profile offers additional control over the rendering intent. This affects how colours that are out of gamut, i.e. colours that exist in Adobe RGB but cannot be contained in sRGB, are treated. 

The two options applicable here are Relative Colormetric and Perceptual. Simplistically, Relative colormetric moves out of gamut colours into the smaller gamut, Perceptual does the same with out of gamut colours but also moves some in gamut colours to maintain a perceptual difference between them. Which is best depends on the individual image.

You can turn on proof colours and see where those changes as you switch proof on and off and then adjust the image accordingly.

Dave

[alexsalvatoretrotta]

Hi @davescm! 

Thanks for the explanation.

By default, I keep it on relative colorimetric in the Color settings.

So when you use the Save for web feature, it doesn't use the conversion options in the Color Settings? Did I get it right?
(So: Relative Colorimetric Intent, Use Black Compensation, Use Dithering)

[davescm]

Yes Save for Web will use your defaults but will not give you the functions to override them (provided the profile contains the tables to do so)

Dave

[TheDigitalDog]

Mucking up things further:

https://ninedegreesbelow.com/photography/srgb-profile-comparison.html

Using Adobes installed sRGB profile, Convert to Profile or Save for Web; no difference.

[alexsalvatoretrotta]

@davescm Ok, so ALSO the Convert to sRGB function in Save for Web uses your default color settings (Intent, Compensation, Dithering).

So if I use the function in Edit > Convert to Profile, or, Save for Web > Convert to sRGB, should the conversion and result be the same, with the exact same sRGB color profile? (considering my workspace is sRGB IEC61966-2.1)

This is right?

It is clear that if I need to do a particular conversion with settings other than the default, I will use Edit > Convert to Profile.

I also noticed that the document is CMYK native and you want to do the conversion, in this case you need to do it from Edit > Convert to Profile (and not from Save for Web as the output will be without profile color tag).

[TheDigitalDog]

The check box Use Dither (8-bit/Channel Images) is used when converting 8-bit per color images. It allows Photoshop to mix colors in such a way that aliasing is reduced when conducting color space conversions.
Visually the difference is pretty tiny.

[D Fosse]

To be clear: your working space doesn't matter. The embedded profile will always override it (if there is one).

And again - rendering intent is moot with standard working RGB profiles. You get relative colorimetric whatever you choose.

[Stephen_A_Marsh]

To convert first, I mean:
Open the Adobe RGB image > Edit > Convert to Profile (sRGB Profile ...) > Export > Save for Web > Embed Color Profile, Convert to sRGB.

I have looked at both images exported with the 2 methods, and they are visually identical, but reading the histogram data the data changes slightly.

Thank you!

By @alexsalvatoretrotta

Is that a typo? Why convert twice?

Any colours that exceed the sRGB gamut will be clipped.

Standard sRGB profiles only have a relative colorimetric table. You could try an sRGB profile with a perceptual rendering table (generally found in output printer profiles, not working space profiles):

https://www.color.org/profiles/srgb_appearance.xalter

https://www.color.org/srgbprofiles.xalter

Once converted to sRGB using both methods and viewed in a web browser, you can then make your own call.

[davescm]

'Standard sRGB profiles only have a relative colorimetric table. You could try an sRGB profile with a perceptual rendering table (generally found in output printer profiles, not working space profiles):'

Very good point Stephen 🙂

Dave

[NB, colourmanagement net]

"

Standard sRGB profiles only have a relative colorimetric table. You could try an sRGB profile with a perceptual rendering table (generally found in output printer profiles, not working space profiles):

https://www.color.org/profiles/srgb_appearance.xalter

https://www.color.org/srgbprofiles.xalter"

nice tip Stephen, good to know

neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

[NB, colourmanagement net]

Doing it using Edit > Convert to profile allows you to choose the rendering intent. That’s how I'd do it, you also get the opportunity to preview the changes and MAYBE alter the original still in Adobe RGB before converting. 

Moving images to a smaller colourspace can "clip" detail in areas of high saturation. The histogram will reveal clipping 

I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management