Actually the chroma variants for increasing colourfulness are bigger than Dcam3 to be able to work. They are progressively uniformly larger versions of Dcam3 (different primaries) which are to be assigned and NOT converted to for the effect to take place. It is like changing the units and not the numbers. 1 cm → 1m. By this change of units, “1” is now physically a greater distance. Similarly, the chroma variants that decrease colourfulness are progressively uniformly smaller versions of Dcam3.
BTW the LUTs of DCP camera profiles are limited to Prophoto primaries, if I understand Anders Torger correctly. I’m not entirely sure what meaningful differences there will be in using ACEScg over Prophoto.
@Keentolearn@samuelchia I am not looking for an answer per se but rather if there is any specific our friend wants to say about replacing the default working profile with another.
Correct me if I am wrong: I am getting the impression that we are becoming preoccupied with the terms and concepts rather than the practical implications of them. My advice is start playing with raw files and make actual comparisons. PlayRaw is the perfect way to do that.
Be aware that some linear transformation are not independant of the working space in which they are performed, mainly when there are multiplications.
For instance, if you use channel mixer (matrix multiplication) in different WS, you will get different results.
Interesting. So the values out of prophoto gamut could be clipped if using a DCP?
Does’t it mean that there should be a way to assign (and not use) a color profile to the generated output?
It seems also mean that DCAM3 is an output profile?
Will be clipped. Exactly. The DCP must be an LUT profile specifically for this limitation to occur. Which is also why I’m uncertain about how advantageous it would be to switch to ACEScg. I doubt it will make any material difference even to a fussy regular photographer.
It was intended to be used in Photoshop where assigning profiles can be easily done.
Dcam3 is a working space RGB profile like sRGB, Adobe RGB, Prophoto etc. and I don’t mean “Working Profile” in the case of RawTherapee. Indeed it would be what you can use as the “Output Profile” in RT, although I normally think of output profiles as device profiles like display and printer.
@afre
Vast debate where everyone has their point of view. It’s like now everyone is a virus specialist and an epidemiologist
I think, Prophoto, is not the best, because blue Y is near of zero. With this choice some sliders are almost without action.
In addition these colors (deep blues with very low luminance) are barely visible or invisible
Widegamut, ACES_AP1, Rec2020 seems good enough
The input profile is the only profile that you assign in the literal sense: you choose how you want to interpret the input pixel values. Is your source encoded in sRGB? Then assigning an sRGB profile as your input profile is the only reasonable thing to do. Assign a different profile and your image won’t look right. Is your source a camera raw file? Then you need to assign a camera specific ICC or DCP profile to get your colors right.
The input profile converts input values to the XYZ reference color space, and then, usually, immediately to your working profile. There is no way to ‘assign’ this profile. The working profile is a large color space in which you can safely do your (non)linear image editing. A large space, like ProPhoto or ACES AP0, gives you plenty of room for (extreme) edits to your image, without causing color clipping or banding (assuming you work with floating points). Importantly, many image operations (edit: not all) require a linear profile (i.e. TRC with gamma = 1.0). Using a different gamma in your working profile will cause unexpected or undesired effects. All working color spaces in RawTherapee force a gamma of 1.0 (in other words, you only choose the primaries).
There are some caveats like @gaaned92 and @jdc point out: some tools are linked to the shape and size of the color space. That is simply how some operations need to be performed. The choice of primaries therefore influences how these tools work. That is why changing your working profile after you finished an edit, is generally a bad idea and may change your colors significantly. Simply pick a large enough color space when you start and then don’t worry about it anymore. Chances are you will never encounter any issues while editing.
Finally, you can choose an output profile. This profile should be determined by your intended medium. If you go for print, pick a printer profile. If you go for the web, pick sRGB. When there are differences in the gamut of your output and working color spaces, some gamut mapping needs to take place. There are multiple ways to do this (perceptual, colorimetric, …), which all slightly change the final look of your image. But this is the only function of the output profile.
Then onto the DCam profiles. If the profile is large enough, then sure, you can use that profile in place of ProPhoto as a working profile.
Holmes’ claims about “better perceptual linearity” with his “proprietary tone curve” for a working profile is complete nonsense. That is not the point of a working profile at all. You may want to do that for an output profile, but then the question is: why do you need such a large gamut in case of DCam3/4/5? Your intended medium probably doesn’t cover it.
So my main claim here is: anything that applies a specific look to your image (deliberate changes in chromaticity, adding of a tone curve) should never be done through any of these profiles. Unfortunately Holmes disagrees with me
Or any other wide gamut, for the sake of completeness.
There’s one instance where it is the way to go: when you use a raw processor as an intermediate application to perform non-raw edits (as wished by @Keentolearn), or as a starting point for your image, that will be further processed in other programs before arriving to the final image.
wow
if we apply chromaticity in Lab adjustments; Lab values become L=40 a=55 b=-58 as well in sRGB than Prophoto, because we stay inside the sRGB gamut; c) if we choose a color, close enough to the sRGB gamut limits, but inside the gamut: L=40 a=63 b=37 and we apply chromaticity +30, Lab values become - Prophoto L=40 a=81 b=49 - we can notice that the hue is preserved (arctg(b,a)), and in sRGB L=44 a=69 b=50 – the hue isn’t preserved.
Thank You Samuel…im learning again
The “better chroma” is “better” in the sense that if you want to increase the colourfulness of your image, you are better off with such an adjustment than the typical saturation slider which honestly is pretty awful. I agree… Joe Holmes talks about Epson Ultrachrome K3 inks being just a tad too rich (saturated) for DCam 3 profiles…solution… assign a saturation variant to DCam3 MASTER PROFILE to talk back to and handle the cheeky Epson INK K3 upstart…choice is ours …use a slider or find a smarter way to do the same thing… I’m certain (looking at the high quality of the photos on the RT front web page) that very smart ways have not been a problem to you guys and girls . anyway…
I certainly do not know.but …
I sense that DCam profiles are doing things the LAB way rather than the RGB way…lots of AB adjustments but no pressure on Luminosity. I also sense that he is trying to match the tone curves of the DCam range of working spaces to fit into the printers tone curve…If Imageprint (amongst others) make a decent living polishing up printer profiles to print better than the printer company can print … is there not also a market for doing the same thing for working spaces which predominantly service printer devices ? I don’t know
BTW the LUTs of DCP camera profiles are limited to Prophoto primaries, if I understand Anders Torger correctly. I’m not entirely sure what meaningful differences there will be in using ACEScg over Prophoto.
Thank You for raising that point
Could you please quote using the quote functionality instead of quoting in bold? That would be much more readable … and also gives more attention to your reply
Unfortunately, you are making a point about nothing here. Holmes’ Dcam spaces are RGB “working space” profiles. This is what the UI is called in Photoshop and how Elle Stone refers to such profiles. Don’t confuse it with “Working Profile” that is used within RawTherapee which refers to the internal calculation space which ignores any TRC if working on raw images.
As such, the TRC of the profile does come into play since it is about “output” - I mean output in the same way as you have defined “output profile”. Don’t get mixed up…
The Dcam spaces do not add a look. This is the second time I’m repeating this. They are intended for use as an “Output Profile” in RawTherapee and also as a “Working Space” profile in image editors like Photoshop, NOT as the internal “Working Profile” inside RawTherapee, except in this unique instance where @Keentolearn wants to use RT as an editor for a non-raw, already-processed image encoded in this space.
To be even more clear: When you use the Dcam spaces as the “Output Profile” in RawTherapee, the output file will not have a “look” applied to it by the Dcam profile. They behave no differently to the user than any other well-behaved RGB working space profiles. I’m rather surprised that there even is confusion about this.
Hmm…I’m pretty sure Joe didn’t say that. It doesn’t even make sense. What does it mean to say printer inks are too saturated for Dcam 3 profiles? If you mean - “UCK3 inks on some glossy media can attain a colour gamut wider than Dcam 3”, that would make sense.
That makes no sense to me also. Assigning a chroma variant in Photoshop modifies the colourfulness of the image uniformly. This is based on aesthetic decisions. On the other hand, to “handle the cheeky Epson INK K3 upstart” requires good gamut mapping from your source profile (document space) to destination profile (printer space). Assigning chroma variants won’t help you there.
The Dcam space’s TRC was designed with the intent of being “more perceptually linear” (than gamma-based TRCs or even L*) in Joe’s opinion, not with the primary intent of matching the printer’s tone curve. In fact, different printers have different tone response so it would be impossible to try and match it with a single TRC. A well-behaved printer aspires towards perceptually linear output, so ideally its tone curve is a reasonably close match to the one in Joe’s profiles. When Epson improved the driver tables for the Pro Stylus models back in the day, it happily brought their native tone response much closer to Joe’s proprietary tone curve and thus this design had this as an added bonus. Having the curves match closely is a big deal to minimise quantisation if you are working with 8 bit images and 8 bit conversions. It is not longer an issue with high bit processing that is recommended today. That’s why I mentioned earlier that having this special TRC is not so relevant today anymore.
Anyway, @Keentolearn did you manage to figure out how to add your own “working profile”? Guess what, in a different thread I was dealing with a different problem which required me to also do this, which I have never done before, and thanks to your asking here, I was able to successfully do this after some mild struggle.
I tried the tidying up of the DCam profiles so that the filenames matched in MacOs/ pictures and in Json…(copy and paste)
I’m not there yet but right now my situation is to stay backstage on what is merely a technical issue and soak up the tremendous flow of knowledge that is exploding around me…
You have proved that Custom profiles work in RT and thats good enough for me to continue until I find out what the problem is.
One point …the Json file never becomes a Colorsync controlled profile? …does RT become the application to open the Json profile …if its not in the Colorsync stable …Right? ps. I’ve always used Mac systems and rarely use Terminal in Mac unless I’m forced to…
Hmm…I’m pretty sure Joe didn’t say that. It doesn’t even make sense. What does it mean to say printer inks are too saturated for Dcam 3 profiles? If you mean - “UCK3 inks on some glossy media can attain a colour gamut wider than Dcam 3”, that would make sense.
i was’nt specific enough…
what Holmes actually said and I quote from his website " when a chroma variant set is used to control image color, the issue of the working space not being large enough to encompass all the colors that every printer can print ( as for example Chrome Space 100 and DCam 3 do not encompass the entire gamut possible with EPSON’s new UltraChrome K3 inkset ) largely vanishes because the space expands as you push colors outwards to the point where you could print those out-of-working space gamut colors (which did’nt exist in the image to begin with) anyway "
My comment :I suppose alternatively, we could skip across to DCam 4/5 or Prophoto in 16 bit…Holmes has variants too for Pro Photo and no Im not his agent!
It’s all on his website and much better described than I can manage.
One other thought… Holmes suggests that we think about what colors we want to photograph first and then think about the smoothest way to get those colors down on paper.
I also agree with you about an earlier comment you made about having respect for the input process first …not the output printed product being the most important issue…I like landscape color and I like K3 inks for printing those colors and I also keep the master file intact waiting for the post digital era. optimism
That is, a color space designed to process the image with it.
Which is, indeed a «working profile» designed to process the image with it. Do you see the analogy? The difference is that RT works in linear space, that is, without TRCs
I’m sorry, but when I was a Photoshop user, I understood by the many posts, articles and tutorials I read, that a working profile, with its TRC, was meant to edit the image, and it could also be the color space (or profile) of the output image, or not. My very last step right before exporting the image was always to convert the color space to a better suited one (usually to sRGB).
If they are designed to increase saturation of an image by just assigning them, then they do have a look (or an immediate result) that other spaces doesn’t offer.
And by the way, the fact that you’ve already said that doesn’t mean everybody MUST understand or agree with it. You should have the patience to explain it again, preferably with other words or other facts that made it clearer to the people that still has doubts. You’re not necessarily in possession of the truth, and if you are, then explain it to us 3-4 times, or as many times as necessary, until we understand it and agree with you.
Sorry, I don’t see the analogy, what is the contrasting example you are comparing to as an analogy?
Certainly one can insist on the use of Dcam spaces as the “Working Profile” for RawTherapee to process the image with, which will then ignore any TRCs embedded in them. We have no disagreement here at all.
Yes, we do not disagree at all on this also. The difference is Thanatomanic is talking in the context of RawTherapee, not Photoshop. When you talk about working space profile in Photoshop, it is always using the TRC of the working space profile, is it not? But when you talk about the “Working Profile” (in the words of the RT user interface), it ignores the TRC of the profile, even if you set it to your own custom profile which has an embedded TRC, is this not the case?
So Thanatomanic was insisting that the -
How is it complete nonsense in the context of Photoshop, or when the profile is used as the “Output Profile” in the context of RawTherapee? But of course it (meaning the TRC) is “nonsense” when used as the “Working Profile” in RawTherapee since it (TRC) is ignored.
Perhaps now @XavAL can see that we have no disagreement between me and you.
The Dcam spaces are not designed to do that. This is a gross misunderstanding. The Chroma Variants are what is used to increase saturation. Two very different things. The Dcam spaces are like e.g. sRGB, Adobe RGB etc. just normal RGB working spaces.
Let me try then to break it down for you. Say you are working on an image in sRGB. Then you assign Adobe RGB to it in Photoshop and of course the colours change. Can you say that Adobe RGB is a profile that “adds a look”? Can we also say that since Adobe RGB has a TRC of Gamma 2.2, this is complete nonsense and thus cannot be used as a working profile [for RawTherapee]? Of course, this is wrong.
Some folks are confusing the regular Dcam spaces with the special chroma variants of these spaces. To put it another way, the Dcam spaces are what you convert to just like any other regular RGB working space. The Chroma Variants are what you assign to modify the colour.
Joe has made chroma variants of Adobe and Prophoto as well, which modify saturation when you assign them to your images that are in those respective colour spaces. The chroma variants are essentially AdobeRGB/Prophoto/Dcam X spaces with their primaries slightly modified, shifted outwards or inwards if you like, such that the RGB space is then uniformly larger or smaller (in reference to Lab space). As such, the effect of assigning these chroma variants allows one to increase or decrease chroma with exactly the same visual effect as the Lab chromaticity slider in RawTherapee. That’s all there is to them. And you don’t have to use them at all if you don’t want you, you can just use the regular working spaces alone as normal working spaces which certainly do not add any looks and do not modify saturation one iota.
I assume the confusion arouse out of Matt’s writing which was initially very convoluted with lots of misleading/wrong points, which I’ve tried to tease apart as you can see. It seemed only to fuel others to drive the conversation further away from his main issue, and even raised some ire about Joe Holmes’s writing style and pricing strategy which seems misplaced in the context of the thread, along with repeated false accusations about how the profiles work. I had wanted to refrain from fanning the flames even more, since I have no intention to convince anyone to switch to using Dcam spaces. Joe’s articles about them and how they work are there for anyone to read, but continuously insisting on a false statement after someone tells you it is incorrect is not helpful towards learning.
It goes both ways. I cannot force anyone to understand something they don’t want to understand. I’ll leave it at this for the time being, hopefully this clears the air once and for all.
I have never used Photoshop extensively, but after re-installing it, playing with it and reading this and this, I understand things better. @XavAl’s explanation seems correct. Apparently Photoshop intends for you to only pick one color space and assumes you use soft-proofing to ensure your colors will look right on your medium. Then if you don’t show the advanced options on export and pick an different color space there (the output color space), Adobe assumes your working space is your output space. This space will be embedded in your exported file.
So the key difference here is that the choices for working color space and output color space (or profile, whatever you like to call it) is more visible in RawTherapee than in Photoshop.
If it does, that would be very bad for many editing operations. See here for more information: https://ninedegreesbelow.com/photography/test-for-linear-processing.html
Elle’s conclusion is that for Photoshop “Some editing operations and blend modes are automatically linearized, and some are not, and some editing operations are linearized at 32-bit floating point, but not at 16-bit integer precision.”
The key difference here is that in RawTherapee the TRC is ignored so you always operate in linear RGB mode.
Well, agreed on the regular DCam spaces. But Holmes doesn’t advertise his chroma variants any different than his regular DCam spaces. That means he implies they are working profiles too, right? That means a look is applied, which is not what a working profile should do. But since Adobe muddles working and output profiles together, I guess you can say that things are all right in the end?
This is still something I don’t understand. Can you explain what you do in Photoshop that makes these operations uniquely different?
Edit: I must correct myself from earlier statements where I strongly advocate to work in linear RGB space. While this is sometimes true, that is not always the case. Coincidentally, there is a recent nice post here that gives a few examples of operations that you want to do outside linear space. I think that Adobe may have the philosophy “use the TRC from the working profile and work in non-linear space by default, but internally convert to linear when necessary”, and RawTherapee is the opposite “ignore the TRC, work in linear, except in some cases”.
Unfamiliarity with the GUI of an app you don’t typically use does not mean its functionality is any less visible objectively, though subjectively you are right. It is less visible to you.
We need to break this down properly. Firstly, let’s look at RawTherapee. You can only pick one colour space for each of input, working and output. Only one. It is a raw converter and image processor, so the data has to necessarily move through several transforms, but only one colour profile can be used at each stage. Photoshop is no different in this regard.
Photoshop is just a raster image editor that works on non-raw images, raw images have to be processed by its plug-in, Adobe Camera Raw, or some other software and sent to Photoshop in a format it can parse. The image file can have only one profile associated with it at a time.
When you open your document, Photohop honours the embedded profile by default. If there is no embedded profile, you can assign a profile to your document. This is similar to the “input” profile of RawTherapee, though for RT it is usually a camera device specific profile for raw images, while usually in Photoshop you are assigning a device-independent working space profile. Photoshop can even use CMYK profiles and more which RawTherapee can’t.
The document profile is also the “working profile” (using RT speak) in Photoshop. This should be easy to understand.
The user can save the document as is with the current working profile. There is also a function to “Convert to profile” which is similar to the “Output Profile” in RawTherapee. You can choose to convert to any profile and choose the desired rendering intent and save that as another copy of your image or override the current document.
assumes you use soft-proofing to ensure your colors will look right on your medium.
Softproofing your image will not make it somehow look right in your chosen output medium! This is no different in RawTherapee. In softproofing, there is no actual change to the document’s profile as it stands. It is merely an on-the-fly simulation.
You still have to make the deliberate choice of converting to the correct output profile, just as you would do in RawTherapee.
Edit: I see you changed your post on this point as I was making my own. Please read on further below to see I acknowledged it.
I was generalising a bit there. Indeed certain functions in Photoshop can operate in linear mode even if the working space profile is non-linear. Photoshop also doesn’t have true 16 bit support, it is more like 15 bits + one signed integer. Some editing operations are forcibly 8 bit only too. It is too complex a program to describe in few words, but generally speaking, Photoshop honours the TRC of your working document.
That is not true in all situations also. If you set the working space TRC to a custom one, RGB operations in RT will not operate in linear mode. Also, you can choose log for resampling in geometric corrections. There are possibly others which are not coming to mind just now…
Hmm, honestly I have no idea what you really mean by this.
Yes, the chroma variants can be used as working profiles. If you use them as such, they cannot (read: totally impossible) modify saturation whatsoever and will not impose any look whatsoever. On their own, they behave normally just like any well-behaved RGB working space profile.
You must understand that Photoshop is not like RawTherapee where you can make edits, close the program and somehow those parametric edits are saved and associated with the correct document. Photoshop is old fashioned. You open a document, working on it, save it. Certain operations are destructive, after you save the file, and then open it, you can’t go back to a previous state. So this file can only have one color profile associated with it at any given point in time, period. This doesn’t mean “working” and “output” profiles are muddled. Photoshop has what is called the “Document Profile”, which is the current profile that is selected. It is up to the user to change it depending on their needs, whenever.
I recommend you to try this. Start with an image, JPEG or TIFF, which you have saved with the sRGB profile with its standard TRC (not gamma=1.0). Open it in RawTherapee’s editor. In the “Input Profile”, select Adobe RGB Gamma 2.2. Or maybe ProPhoto RGB Gamma 1.8. What happens? Your images colours are shifted right? The look has changed, right? They are more saturated, right? Do you say “a look as been applied”? So can we say Adobe RGB and Prophoto RGB are not doing what a working profile should do? No, of course not. Now why is that? Is it because they are badly designed? No, it is because you are using them the wrong way which is causing you to have this thinking. I am asking you to assign AdobeRGB/Prophoto RGB to an sRGB image, not convert. That is why the “look” changes. It is not due to the profiles but rather how you used them.
The chroma variants work exactly the same way. It is an unconventional way of using profiles to modify saturation, by assigning them in this way. It does not mean that they don’t behave like normal working profiles when used as such. If you instead have converted to the chroma variants, you will see that the image’s look does not change at all. Zero change whatsoever.
There is nothing special about the way Photoshop works with profiles that is unique. It is based on the same colour management principles as RawTherapee. Maybe you need to have a deeper understanding of what it means to assign vs convert to a profile. This is independent of Photoshop and RT. If you don’t understand this well, there is no point in continuing this discussion.
Beautiful! Yes! :)) Linear does not always been better. The main difference is Adobe is working on non-raw images which typically have gamma-encoded profiles (i.e. what you output from RawTherapee or other raw processing software), while RawTherapee typically works on raw images. Hence the observations you have made.
