What profile is Untagged RGB

[Lukas Engqvist]

Just need to check what you are using. I'd also love to hear the arguments you have. I am hoping all agree, but please be honest.

 

[TerryWyse]

The "correct" answer is to leave no image untagged but assign/embed something so downstream color management is going to be predictable rather than at the mercy of what person or system gets the file next.

Having said that, encountering an untagged RGB image at least says *something* about the color IQ of the person who gave it to you...that usually means the safest bet is to assume/assign/embed sRGB.

In a perfect world (and how I train folks to approach an untagged RGB image) is to start by assigning sRGB, AdobeRGB, ColorMatchRGB and ProPhotoRGB, roughly in that order, and see which is the most likely candidate (as seen on your proplerly calibrated and profiled display of course!).



Terry

 

[Lukas Engqvist]

Since there are formats that don't support tags, and other programs that don't honour tags, there must be a procedure for "incorrect" files... or are we saying .gif, and .png are incorrect under all circumstances?

 

[DCurry]

I use sRGB as my default for untagged images. The reason is that we get a lot of non-professional digital photos from consumer-grade point-and-shoot cameras, and even if they are not technically shooting in sRGB it is pretty darned close. If I default to AdobeRGB, untagged photos tend to look too red.

 

[Stephen Marsh]

In a world where one size fits all, where one is after repeatable results if there is no profile tagged to the image (rather than pleasing or "correct" results)? = sRGB

One could pick sRGB for consumer/office customers, Adobe RGB for graphic designers and Pro Photo RGB for photographers...if you knew who was who...and some photographers use Adobe RGB - so it is really hard to make blind assumptions. Not to mention that in Europe ECI RGB may be more common than Adobe RGB etc.

In a world where you have the luxury to second guess the folk supplying you files? = I use the Photoshop action attached to pick the "most pleasing" result, hand in hand with the info palette set to L*a*b* and or other values (in addition to a profiled monitor preview).


Regards,

Stephen Marsh

 

[Lukas Engqvist]

@Steophen oops I didn't put colormatch RGB as an option :S the "newsprint" RGB, there was a period we that was what was in circulation... 15 -12 years ago before the www was stable mind you.

 

[Stephen Marsh]

I don't think it is that big an issue Lukas, Apple RGB and ColorMatch RGB seem to have had their day (as has Bruce RGB, Don RGB etc). sRGB would appear to be the low end standard. Sure one can include these two similar 1.8 gamma profiles, however times have changed and I would presume that most OS X users have a monitor more similar to 2.2 gamma than 1.8 (and yes, I know - sRGB is not exactly 2.2 gamma).

Reading over my post, it would appear that I need to update my action to include ECI RGB!

Stephen Marsh

 

[rich apollo]

Since there are formats that don't support tags, and other programs that don't honour tags, there must be a procedure for "incorrect" files... or are we saying .gif, and .png are incorrect under all circumstances?

GIF will be in the colorspace of your monitor, by default, won't it? It is incapable of carrying an ICC profile, and so is simply RGB values being sent to your monitor.

PNG, can carry a profile, as Leonard told us on your other thread, but that depends somewhat on the software writing the file. There is a "chunk", as the spec calls it, that is dedicated to ICC profiles, but it may not get written. Without a profiile, PNG is assumed to be sRGB, unless it's grayscale.

GIF and PNG would be "incorrect" for print purposes, in my opinion. The output channels that they would be appropriate for, epub or web, don't support ICC profiles well, if at all, do they?

 

[Lukas Engqvist]

GIF and PNG are quite common in technical manuals, especially if they are manuals that explain how to use a screen interface. So I would say they may not be "design" files it does not disqualify them as appropriate for certain kinds of print. In reports, courseware, books that accompany a seminar etc they are normal, and printable, if handled correctly.

 

[buckeye]

You guys make my head spin.

 

[rich apollo]

I'm just trying to keep up with the Swede - ;•)

 

[Magnus]

We use..

We use..

Our default RGB is set to Adobe RGB 1998, and that's the profile we use on all our own RGB artwork as well.

Haven't seen the benefits of ECI RGB yet, if anyone can wants to convert me (sorry for the icc-joke) please go ahead!

 

[mglouis]

Fleshtones are the common point of contention. I rarely hear any fuss about other subject matter.

We use aRGB in our offset division where subject matter is varied and sRGB for digital where we get a lot of fleshtones coming from consumer-level digital cameras.

Matt Louis

 

[Lukas Engqvist]

@Magnus even for untagged images? Do you inform customers of this policy? The ECI RGB was more of an issue when comparing slides to screen since the white point had to be the same on monitor and light table (Adobe RGB is 6500k and ECI RGB is 5000k)

 

[Stephen Marsh]

The following sort of sounds like religious debate of creationist views vs. evolutionary views!

ECI RGB was created, and updated - by design.
Adobe RGB 1998 was created by accident - human error, a typo that escaped quality control back in Photoshop 5/5.5 (long before CS was added to the name).

That being said, I don't hold religious views on the choice of RGB working space, I have one default but use whatever is "best" for the image, edits and output at hand.

Stephen Marsh