Film Scanner .ICC Profiles and Photoshop/Lightroom

[Scott J.]

Howdy,

I'm a little confused about how an embedded custom .ICC profile for a film scanner gets handled when a film scan is opened in Photoshop and Lightroom. I've read a great deal about ICC workflows online and have tried to make sense of it all, but the explanations frequently seem a bit impenetrable (lots of vague, jargony language) and I'm usually left with a sense of not knowing what exactly is going on "under the hood" between different applications is the workflow. My confusion stems from three questions:

1. Let's say I've created a custom RGB .ICC profile for a certain film type (e.g., Velvia 50) on a certain scanner using an IT8 target. If I scan a piece of film and have the "Preserve Embedded Profiles" option active in the Color Management policies for the scanning software, does the custom .ICC profile in question also need to be installed on the computer system more generally (i.e., Windows>System32>spool>drivers>color) for other applications (Photoshop, Lightroom, etc.) to know how to correctly display colors in the image?
2. As a related follow up: If that custom .ICC profile hasn't yet been installed on the computer system more generally, how do other applications handle interpreting the colors? Presumably, an application like Photoshop can at least still see the name of the embedded profile, but won't know how to interpret the colors owing to the fact that it (Photoshop) doesn't have access to the instructions contained in the custom .ICC file. Does Photoshop just resort to using a default, generic profile (e.g., sRGB, Adobe 1998, etc.) in a case like that?
3. Photoshop is conveniently able to show a user the active .ICC profile for an open image, as well as offer options for converting the image to a different profile (i.e., Edit>Color Settings), but don't see a similar option in Lightroom. That has me wondering: Is Lightroom able to read the name of an embedded profile, look up its corresponding .ICC file, and display colors correctly? Or does it simply use a single, canned profile for all images (e.g., Adobe 1998), irrespective of embedded profile?

Hoping someone can sort me out! Many thanks!

 

[_T_]

You can and definitely should embed the icc profile of your film and scanner combination in the files you produce but that doesn’t mean that photoshop is going to display the file in that space.

Photoshop has its own working color space into which the data from your file is interpreted vis a vis your embedded profile. I assume lightroom does this but with less options I don’t use lightroom.

Then the output of photoshop gets interpreted by your operating system into the color space required by your monitor using the icc profile that you have your os set to use so that you can see it on your monitor.

You don’t need to install the icc profile for your scanner and film on other devices in order for them to see your files, that’s the icc profile that the os is using to communicate the colors to whoever’s monitor and if they try to use your scanner’s profile for that the colors will look messed up because the monitor can’t display those colors.

Before you send your files to anyone else or look at them on other devices besides the one you use to edit your photos (in ps or lr or whatever) you need to convert them to a common color space like sRGB or else other devices won’t know how to interpret the color the way you’re seeing it in photoshop. They’ll have to do their own interpretation of the data in the file and who knows what that will look like.

The end user should have the color profile they need to interpret the file you give them as long as you embed it in the file. That’s all that’s needed is the embedded profile. Just like all you need is the profile your scanner software embedded in the file before you edited it.

 

[Scott J.]

Thanks for the explanation, T.

Is it correct to say, then, that "embedding" an .ICC profile in a film scan doesn't just tag the file with the name of the .ICC profile (e.g., "flextight.icc"), but also embeds the mathematical instructions for how another computer (or piece of software) can go about interpreting the colors? For example, if I create a film scan with a Flextight scanner connected to one workstation using "flextight.icc" (just as a hypothetical example), then open that image file in Photoshop on another workstation that doesn't have "flextight.icc" installed, will Photoshop still be able to correctly display the image because the image file already comes bundled with the mathematical instructions needed to interpret the colors?

Assuming the above is true, is it the "Working Space" profile I have saved as a preference in Photoshop (e.g., ProPhoto RGB) that determines how Photoshop interprets the color?

As a side note, I did a little digging and found that Lightroom uses ProPhoto RGB as the default working space in the develop module, and that this setting currently cannot be changed. The fact that it can't be changed seems to confirm my two assumptions above. I.e., if the ability to manually select a working space profile in Lightroom isn't even possible, it must mean that the embedded profile contains all the info needed to perform the color interpretation, and that therefore, copying the custom profile (e.g., "flextight.icc) onto several different machines isn't necessary.

 

[_T_]

You basically have it but there are a couple points.

An icc profile doesn’t contain the mathematical instructions for interpreting the data in the image file. All an icc profile does is describe the specifics of the color space into which the data from the file was recorded. The mathematical instructions themselves are made by the software by reading the icc profile and using that information to determine what operations must be performed on the data in the image file in order to display the image.

The exact mathematical instructions the software comes up with are generated based on the embedded icc profile, the destination icc profile and the color data contained in the image file.

When you embed a profile into an image file you are embedding a copy of the icc file into the image file. So like you say you are embedding everything the software needs to be able to interpret the colors. Whether or not the colors will be properly interpreted on a given piece of software on a given device is a different story. That’s why you must convert the file to some kind of standardized color space like sRGB before distribution in order for your images to look right on a variety of other people’s systems.

The only system that needs to have your icc file that you generated by calibrating your scanner saved on it is the computer that is going to be running the scanner. It must be saved on that computer in order for your scan software to embed it in the image file, but once the scanning software embeds a copy of the icc profile from the file saved on that system it will travel with the file so long as you make sure that the embed color profile option is turned on in ps or lr. It is possible to discard the embedded profile when you are saving an edited image so be sure that the option to embed the profile is enabled.

 

[250swb]

Howdy,
Does Photoshop just resort to using a default, generic profile (e.g., sRGB, Adobe 1998, etc.) in a case like that?

It's not 'just resort to' but that is how you do it. Picky points aside the default image profile should be Adobe RGB as a TIFF, or sRGB for a JPEG. ICC profiles come into play when you want to print the image not as your default colour space, not when you are generating the image or post processing the image.

 

[_T_]

I’m sorry 250swb but that is not quite correct. ICC profiles play a role at every step of the digital image chain from capture (whether by scanner or digital camera) through editing and on to display (whether on a screen or as a print).

Each device has its own color space in which it must operate which comes down to the physical design of the device, so each device must have its appropriate icc profile in order to handle your colors correctly, whether it’s a monitor or the screen of a phone, a camera or scanner, an inkjet printer or a huge press for mass producing offset prints.

At each step the data from the image file is encoded or interpreted and reencoded through the use of the color space assigned to the file to ensure the correct rendition of colors.

Further, the file type in which the data is stored has no bearing on the correct profile to use. The correct profile is determined by the color space of the destination (either a print or for display on digital devices).

Adobe RGB for example is specifically designed for CMYK process printing, it contains a broader range of colors than most screens are capable of displaying which means that if your file is in Adobe RGB there is a good chance that it won’t look right on a given device.

sRGB is still the de facto standard for display on screens in general, although it is pretty old and there have been newer standards that have gained traction such as P3 which has a wider gamut. We are still some time out from the end of sRGB so for now if you want your images to look good on the widest possible range of devices, say for publication on the internet, it’s still the way to go.

If you are printing your own files on your own inkjet printer then it would be appropriate to use Adobe RGB so long as your printer is expecting to receive files in that color space. But if you are paying a professional printer to make your prints you shouldn’t assume that they want Adobe RGB. Always ask for all the specifications that they require of your files. I have worked with a number of printers who expect sRGB in their workflow and if they receive something else it will definitely look bad when printed.

 

[Scott J.]

Really useful information, T. Thanks for taking the time to answer all of my questions so thoroughly.