An excuse to discussing "Great Color" and getting to it!

[Asher Kelman]

I've abbreviated Doug's notes on my brief mention of my ideas on color for my workflow.

Asher Kelman: Girl From a Café #1

New York

"Redheads 2015"

Canon 5D 1.8, 1/100sec, 50 1.2L​

I am very careful in mostly using custom profiles for each lens-camera combination. I obey standard rules of color respecting the calibrations. However, in this case, the files were made with a 5D for which I have yet to create profiles, so I rely mostly on the best sampling for white balance. Only very rarely will I alter color balance by eye, but if I need to, I have a lot of mental memories stored of what the colors should be. Still, that work needs to b done on a cor profiled monitor in dim light with no obvious colors visible, except for that picture. No colored shirts and no magazines or colored coffee mugs on my disk to create a color distraction.

Hi, Asher,

I'm not sure I know what you mean here by "profiles". Do you mean for example ICC source device color profiles? Could you elaborate a bit more. Where are these profiles "applied"? "I obey standard rules of color respecting the calibrations." Could you elaborate a little more as to just what you mean by that?

...........I am surprised by your comment about doing the color work on a display "in dim light". As I recall, the usual recommendation for the environment of the display is one I would not characterize as "dim light" (I don't remember the actual illuminance value just now). Do you find a lower surrounding illuminance to be advantageous? Of course you give some hint as to your motivation in your discussion of "distractions" in that environment.

Doug

 

[Asher Kelman]

1. What is great color?




When we say we like some scene, in real life
or in a photograph, what are we using as our
measures by which we judge color to be great?



I will leave this for you all to answer before we deal with how to get it!

Asher

.............we will discuss how to get it further on.

 

[Asher Kelman]

So let me try. Then, I will present a small sliver of the available methodologies that photographers use.



By "Great color" we likely want to include measures of ideas of


1. "Accurate" in some physical sense, based on the actual energy distribution of photons or the tightness, (i.e. shorter versus longer wave forms), of the corresponding electromagnetic waves emanating from the subject being photographed.


2. Reproducing the vision of how that scene appeared. In general, this would seem to require the same physical determinants as needed in for the photograph to be "accurate", but, likely as not, our brains modified our experience. So some boosting or calming of the image's attention getting colors, might be needed.


3. Reproducing the scene with an impact similar to various types of analog films, such as Kodachrome, Velvia, Portra and the like where recorded colors are remapped so as to be in the style of some favored "look". These films may be described as delivering "richly saturated colors, Velvia or more restrained as in Portra.


4. Reproducing the experiences of that scene. This is where the artist can add an overlay of artistic effects to the remapping of the color, including changes in saturation, range of hues in a gradient, contrast and more - either applied uniformly to the entire picture, or else just in portions of the frame for some "ranking" in the application of the power of the effect to different elements.

Still, we can start with "accuracy", as all the subsequent presentations depend on an accurate reproduction of the kind of light coming from the recorded scene.

In very very simple terms, we can imagine that the names of the MFRs of digital cameras became the equivalent of the analog film styles of old. So some preferred the nikon look for skin for portraits while others like Canon, even though they had a different blush. Similarly in MF digital work, some liked the more seemingly ethereal colors of Leaf while others liked the more down-to-earth reproductions of Phase One.

Here are the rules of use.

Take a shot of a neutral grey card in the light of the photoshoot.

In Photoshop, (after setting the dark and light range), apply that image color by sampling the grey with the white balance dropper.

The color of the picture snaps to the style built in to that camera and the result was a reliable "Great Color". This was simple and anyone could now deliver a picture with "Great color".

But then it was realized that the cameras varied, one from another, even though made by the same MFR. So a number of companies delivered solutions to this. There were now a plethora of ways of analyzing the output to deliver accurate color.

Gretag Macbeth provided closely matched printed targets with an array of reference colors. Eventually this matured to an automatic process where one merely takes picture of the GM card with a particular camera-lens combination. Now the "profiles generated by this simple program allowed production of a curve that could remap the hues in the recorded image file and normalize it to be "accurate". So from now on, files from different cameras should give the same look on the same monitor.

(Of course, it means using a high quality monitor with uniform colors capabilities all over the scree real estate, from the center to the sides and corners. In practice, there are variations and the more high end screens achieve very similar reproduction of color anywhere on the surface.)


Asher


Next I will cover using the Gretag Macbeth cards and the means by which this data is accessed in Photoshop. Only later will we get to what clothes one wears during color editing!

 

[Jerome Marot]

Please watch the last video on this page: http://prolost.com/blog/lutlook.

It explains how filmmakers produce the kind of colours photographers get from plugins or instagram. More importantly, it explains the logic behind the colour selection and what to do so that it looks nice.

 

[Asher Kelman]

Please watch the last video on this page: http://prolost.com/blog/lutlook.

It explains how filmmakers produce the kind of colours photographers get from plugins or instagram. More importantly, it explains the logic behind the colour selection and what to do so that it looks nice.

Thanks again, Jerome for the richness you always add! One can export a frame from Adobe Premier to the desktop, open it in Photoshop CC 2014 or 2015 and then add any adjustment layers to correct the color to one's taste and then export the changes as a 3D color look up table or LUT to now apply to the entire video shoot in Premiere. What I must try is seeing if one can use that LUT for other still images in PS?

Asher

 

[Doug Kerr]

Hi, Asher,

Thanks again, Jerome for the richness you always add! One can export a frame from Adobe Premier to the desktop, open it in Photoshop CC 2014 or 2015 and then add any adjustment layers to correct the color to one's taste and then export the changes as a 3D color look up table or LUT to now apply to the entire video shoot in Premiere. What I must try is seeing if one can use that LUT for other still images in PS?

Very interesting.

What is the significance of the LUT settings you mention being characterized as "3D"?

Thanks.

Best regards,

Doug

 

[Antonio Correia]

In a moment I want to slowly move to color images, all this info is precious. Thanks !

But it looks like Magic Bullet can be used in Photography... Perhaps a bit too expensive...

I have loved the image by Asher since I saw it somewhere but then I had no time to comment !

 

[Asher Kelman]

significance of the LUT settings you mention being characterized as "3D"?

Doug,

Here is a very useful set of quasi-definition/explanations of the different LUT instruments in use for

• Bringing computer or display monitors to within a certain uniformity standard, such as the Adobe RGB Color Space
  
  
• Moving from one Color space to another
  
  
• Correcting to some standard a source device
  
  
• Delivering a Particular Cinematic "Look"

With digital images in Photoshop and other similar post-processing applications, the input source of the image, usually a camera, and the display or printer output of that image file are generally converted to a CIE color space as the intermediate step.

A LUT can do the various conversions in one step and that's convenient for cinematography. 3D LUTs can allow one to adjust multiple parameters across channels and effect deep changes in saturation.

A caveat to the use of creative 3D LUTs is that it may have been created for one specific color space and applying that combination of changes might very well give unexpected results of used in a different color space. So keep a note of the color space!

No one needs to be concerned in still picture work with these tools apart from knowing that look up tables are generated and stored in a computer monitor or on the hard drive for profiled or calibrated monitor or projector. Furthermore, as long as the monitor is regularly profiled or calibrated as needed, you don't actually have to realize that the myriads of adjustments needed to correct your images, (so that what's seen is what can be printed), are in fact stored as a look up table! ?

So if one is new to accurate and creative color work in Photoshop, hold off on applying many changes simultaneously to create a specific look until you have mastered color fidelity or "accuracy".

In the meanwhile one can use creative filters such as Nik, Topaz, OnONE or DXO film pack.

Asher

 

[Doug Kerr]

Hi, Asher,

I get it. This is from the Wikipedia article on 3D Lookup Tables:

A 3D LUT is a 3D lattice of output RGB color values that can be indexed by sets of input RGB colour values. Each axis of the lattice represents one of the three input color components and the input color thus defines a point inside the lattice.​

So this is a table that is three-dimensional in the mathematical sense: it takes a three-value input and the resulting entry ("point") gives a three-value output.

So it is defines a completely-generalized mapping from one RGB space to another RGB space.

Neat.

The context of the article is specifically the use of such tables to provide remapping at the point where the image is to be viewed on a high-precision display.

The article goes on to point out that commonly the table is 17 × 17 × 17 (4913 entries) (and interesting size), and that of course interpolation must be used. It indicates that typically the input is on the basis of 10-bit log-compressed values, while the output is typically RGB values suitable for driving the display proper.

But I can of course readily visualize the use of such remapping tables at other points in the overall image handling chain.

Best regards,

Doug

 

[Doug Kerr]

Hi, Asher,

As I recall, the look-up-tables used in basic display adapters are three one-dimensional tables. That is, each remaps the scale of one of the components (R, G, and B).

These are used in the "calibration" layer of display "preparation", in which the response of the display system it made to conform as nearly as practical to some recognized color space (often sRGB, I think).

Then the use of an ICC profile for the (calibrated) display is used in the processing chain to complete the concept of "proper" output color.

It is interesting to learn of the use of 3D LUT's in modern high-end display adapters. It sounds from your description that these can be loaded by information from the image processing software, seemingly related to color adjustments (like color grading in the digital cinema context) made by the "operator".

I still have to grasp how that fits into the overall process in such cases.

Best regards,

Doug

 

[Doug Kerr]

Hi, Asher,

Reviewing your recent note, it seems as if you are saying that, at least when working with a sophisticated image processing system, that changes the "colorist" makes in the coloration of an image are saved in the form of a set of LUT values.

Now, are those LUT values only saved so that when we next visit the modified image we will see it as it had already been adjusted (certainly an imperative), or is also so that the implementation of those color changes in viewing the particular adjusted image is done by propagating the LUT values into the LUT in the display adapter?

Thanks.

Best regards,

Doug

 

[Doug Kerr]

This is an interesting passage from the user manual for the basICColor display calibration and profiling software:

Some high-end monitor have an internal 3d Look-Up-Table (3D LUT) which allows it to manipulate the color characteristics of the display. This makes it possible to emulate the shape and size of a different color space instead of using the native color gamut of the display. This means a wide-gamut display with a color gamut of about 100% of AdobeRGB (1998) can reduces in it’s gamut to e.g. the shape and size of an sRGB-display.

When a monitor emulates a color gamut it’s not possible any more to show higher saturated colors than the colors of the emulated color gamut. Even when the monitor is able to show those colors in it’s native color gamut!​

This sounds a little different from the use of a 3D LUT in a display system that you discussed, Asher. But maybe it isn't really different.

Perhaps the scheme is to treat the color adjustment made by the "colorist" to a particular image as creating an ad hoc color space for that image. Then., by loading values into the 3D LUT of the display chain (when that image is being displayed, that color space it put into effect, the result being that the displayed image has the color characteristics established by the colorist.

I have to figger if that notion reaches from cover to cover!

Best regards,

Doug

 

[Doug Kerr]

This passage from the manual for the Adobe Lustre 2010 cinema video processing system gives some further insight into this matter:

http://download.autodesk.com/us/sys...3d9a411df9298473-7fee.htm,topicNumber=d0e9292

Here is the introduction:

When you use 3D LUTs, you apply an interactive viewing LUT that works through the NVIDIA® graphics card. The 3D LUT displays how the colour graded images will look on film stock as you work, without impeding processing speed.​

Interesting.

So, Asher, when working with still images, do we do a similar thing: populate the LUT of the display system so as to emulate color changes "made to the image" that in fact have not yet been applied to the image itself (but perhaps will be when the "deliverable" form is saved)?.

This is slightly evocative of the working of the Silkypix Developing Studio, except that there the changes are actually made to the "viewing" copy of the image (in some cases, in a slightly primitive way, for expediency), but are not applied to the "delivered" image until I tell SDS to "develop". (I suppose LR works somewhat the same way, perhaps especially if our display adapter does not have a 3D LUT).

Best regards,

Doug

 

[Doug Kerr]

Well, I find that evidently these days, the ICC profile used to mediate between the standard "internal" color space (the profile connection space, or PCS) and the color space of the (calibrated) display can describe this transform in two ways:

• With a basic linear matrix, which transforms by linear algebra any incoming RGB value triple to an output RGB value triple.

• With a lookup table, which transform by "table lookup" any incoming RGB value triple to an output RGB value triple.

The latter is of course far better than the former in dealing with nonlinearities in the response of the display proper (and is otherwise more capable in describing the needed mapping).

I believe this is wholly unrelated to the matter of the LUT in the display system, whether used for "calibration" or used as a part of the display of a color-adjusted image.

But of course I could be wrong there.

Best regards,

Doug

 

[Asher Kelman]

Hi, Asher,

Reviewing your recent note, it seems as if you are saying that, at least when working with a sophisticated image processing system, that changes the "colorist" makes in the coloration of an image are saved in the form of a set of LUT values.

Now, are those LUT values only saved so that when we next visit the modified image we will see it as it had already been adjusted (certainly an imperative), or is also so that the implementation of those color changes in viewing the particular adjusted image is done by propagating the LUT values into the LUT in the display adapter?

The image effect or look LUT can only be used for that selected image, never to the
display monitor LUT, whatever that monitor might normally address to display the look-3D-LUT-enhanced image! We always have an entiry separate and, (off-limits to PS), LUT for the display and the display LUT, likewise will never invade the territory of the saved or exported image file!

Asher

 

[Asher Kelman]

This is an interesting passage from the user manual for the basICColor display calibration and profiling software:

Some high-end monitor have an internal 3d Look-Up-Table (3D LUT) which allows it to manipulate the color characteristics of the display. This makes it possible to emulate the shape and size of a different color space instead of using the native color gamut of the display. This means a wide-gamut display with a color gamut of about 100% of AdobeRGB (1998) can reduces in it’s gamut to e.g. the shape and size of an sRGB-display.

When a monitor emulates a color gamut it’s not possible any more to show higher saturated colors than the colors of the emulated color gamut. Even when the monitor is able to show those colors in it’s native color gamut!​

This sounds a little different from the use of a 3D LUT in a display system that you discussed, Asher. But maybe it isn't really different.

Perhaps the scheme is to treat the color adjustment made by the "colorist" to a particular image as creating an ad hoc color space for that image. Then., by loading values into the 3D LUT of the display chain (when that image is being displayed, that color space it put into effect, the result being that the displayed image has the color characteristics established by the colorist.

I have to figger if that notion reaches from cover to cover!

Best regards,

Doug

No, the display is now fixed to only remap incoming data in a fixed way decided when the monitor is profiled. In applying a "Look" 3D LUT to the image for some esthetic effect it will be shown on the display according to the existing profile LUT.

Asher

 

[Asher Kelman]

What a LUT does in PS is to provide in one stroke what would take several adjustment layers. If the file is flattened and then the final hues will be specified as if it came from the camera just like that. Then it will be displayed by the monitor using the remapping of those colors into the color space set by the profiling software previously.

Asher

 

[Asher Kelman]

I have infinite patience for getting on the same page in understanding the various LUT needs and uses. We can then edit down the discussion of LUT here in this thread, but provide a new thread just for that!

Once we agree, we can proceed to pretend we know nothing about LUT adjustment systems for any purpose and get on with using a Gretag Macbeth card to calibrate the camera/lens lighting combinations we frequently use.

Asher

 

[Doug Kerr]

Hi, Asher,

I have infinite patience for getting on the same page in understanding the various LUT needs and uses. We can then edit down the discussion of LUT here in this thread, but provide a new thread just for that!

Once we agree, we can proceed to pretend we know nothing about LUT adjustment systems for any purpose and get on with using a Gretag Macbeth card to calibrate the camera/lens lighting combinations we frequently use.

Of course. At your convenience. I'm here.

Best regards,

Doug

 

[Asher Kelman]

Thanks, Doug,

Do you think there remain, amongst your questions, parts that are unanswered or responded to substantially wrong?

Asher

 

[Jerome Marot]

Thanks again, Jerome for the richness you always add! One can export a frame from Adobe Premiere to the desktop, open it in Photoshop CC 2014 or 2015 and then add any adjustment layers to correct the color to one's taste and then export the changes as a 3D color look up table or LUT to now apply to the entire video shoot in Premiere. What I must try is seeing if one can use that LUT for other still images in PS?

I did not intend to start a discussion on Look Up Tables. I intended to answer the 4 points listed in message #3.

What I find interesting in that video is that:

• videographers have access to more powerful color tools than photographers. Probably the reason is that there is more money in video than in photography.
• particular "film looks" are designed by constraining the range of colours around two unique hues chosen to be opposed around the colour wheel.
• one can design "film looks" with colours as crazy as one whishes: as long as skin tones are somewhat preserved, the viewer will find the colours to be believable.

After watching the video, I suddenly understand how, for example, Instagram filters were designed. I had no idea beforehand. Does this ring a bell?

 

[Doug Kerr]

Hi, Asher,

Thanks, Doug,

Do you think there remain, amongst your questions, parts that are unanswered or responded to substantially wrong?

As to wrong, there are so many things I don't know that I couldn't answer that.

As to unanswered, yes. But I think I will transport the discussion of the roles of look-up tables to a new thread.

Press on. I am, anxious to learn about the use of Gretag-Macbeth targets in developing source device profiles for cameras.

And if the matter of metamerism jumps into my head, I promise not to mention it (in this thread).

Best regards,

Doug

 

[Asher Kelman]

I did not intend to start a discussion on Look Up Tables. I intended to answer the 4 points listed in message #3.

What I find interesting in that video is that:

• videographers have access to more powerful color tools than photographers. Probably the reason is that there is more money in video than in photography.
• particular "film looks" are designed by constraining the range of colours around two unique hues chosen to be opposed around the colour wheel.
• one can design "film looks" with colours as crazy as one whishes: as long as skin tones are somewhat preserved, the viewer will find the colours to be believable.

After watching the video, I suddenly understand how, for example, Instagram filters were designed. I had no idea beforehand. Does this ring a bell?

Thanks, Jerome, I realized what your intent was! Thanks the video is fabulous. I'd love that for Photoshop!

A lot of issues such as matching skin tones, getting rid of sunburn and tan lines could better be done with these more sophisticated tools. I will try to deal with these topics down the line, but if you find a great 3DLUT tool for still images, and it can stand alone, then I would be super happy!

As to most of the LUT discussion I will do my tidying up in short order and create a separate thread!

Asher

 

[Jerome Marot]

Some photo software has a colour tool looking like a colour wheel. One can select a colour on the picture and move it around on the wheel. I think it achieves roughly what you want to do. It is indeed mainly used to correct skin tones.

Capture One and Phocus have this tool. Phocus can be downloaded free of charge from Hasselblad and, on an Apple computer, will work with all raw files supported by OS X. That should allow you to try the tool. I you use the tool on an image of the colour wheel, you will immediately understand what it does.

I'll attach two images of the colour wheel under this message:

​

The last image is from this site.

 

[Asher Kelman]

Thanks, Jerome!

I didn't realize the Focus from Hasselblad can be downloaded! I'll do just that!

I do like the idea of the split complementary colors as they are both interesting and also, at least to me, more southing than complementary choices. I appreciate you sharing these color sets!

Just in case anyone following thinks we have lost our sense of reality, let me add the following:

All of our discussion on "superb color" has most often nothing to do with getting to superb photography, as the color palettes are the least important missing component in pictures without staying power. Frankly, the colors out of most cameras, set to auto-everything, is anyway, often sufficiently "awesome" so as not to pull down an otherwise fine image.

So I just wanted to add perspective to interest in advanced color correction and "look" tools, and add some humility to my own position in advocating investment to get the colors that transform that superbly seen scene into a printed photograph, that's not just pretty, but also substantial and worthy of earning its place.

Asher

 

[Jerome Marot]

Just in case anyone following thinks we have lost our sense of reality, let me add the following:

All of our discussion on "superb color" has most often nothing to do with getting to superb photography, as the color palettes are the least important missing component in pictures without staying power. Frankly, the colors out of most cameras, set to auto-everything, is anyway, often sufficiently "awesome" so as not to pull down an otherwise fine image.

That is where photographers and cinematographers have a different approach. Photographers often have this idea that colours should be accurate, match reality, etc... Cinematographers use colour "grading" as a necessary step in their production to get fake colours that represent a certain mood.

Please have a look at the following (rather entertaining) video: Plot device. It has been designed to demonstrate the various moods associated with colour grading.

There is no reason why photographers should not use the same tools and, actually, some photographers do. "Accurate" colours are no more necessary in photography than in cinema.

 

[Doug Kerr]

Hi, Asher,

At the end of the introductory stanza of your tutorial on color management you said that you would shortly be discussing the use of a Gretag-Macbeth color target (or, I assume, its modern successor, the X-Rite Color Checker) to develop source device profiles for cameras (that is to say, combinations of bodies and lenses) under certain illuminants

I will be interested to learn about that.

In the meantime, on a slightly different front, à propos 3D LUT Creator, here:

https://www.youtube.com/watch?v=mZvrj8__5r0​

is a nice discussion of color adjustment at the post-processing LUT level using the Color Checker.

This is part 2 of a series. Part 1 focuses on the technical issues underlying this work.

Best regards,

Doug

 

[Asher Kelman]

Hi, Asher,

At the end of the introductory stanza of your tutorial on color management you said that you would shortly be discussing the use of a Gretag-Macbeth color target (or, I assume, its modern successor, the X-Rite Color Checker) to develop source device profiles for cameras (that is to say, combinations of bodies and lenses) under certain illuminants

I will be interested to learn about that.

Yup, let's go then!

We could use any camera-lens-lighting combination. In fact this should be routine for accurate work with your camera and even the native lenses from the same MFR. However, to see it in action, let's get a combination that really begs for intervention!

I routinely use the Sony A7R with the superb Leica M Summilux 1.4 lens on it! (I mount the lens on an adapter which has both the Leica M mount to receive the lens and the male FE mount of the Sony A7 series of cameras).The camera provides amazing resolution and dynamic range while the lens has the quality to match that in terms of resolution, contrast and beautiful rendering, with one huge caveat. That is a yellow cast over the images!

So we need to correct that color and in each quality of light that will be used.


We need a few tools.

1. Gretag Macbeth color checker.

2. The Adobe utility for converting RAW files from your camera to a DNG format


Simply take a picture of the Colorchecker chart and then import that RAW file to the Adobe utility to get a DNG file.

Here it's filled up to designate the DNG as belonging to the Sony A7R camera with the Leica M Summilux 1.4 mounted on it.

I make a separate file for shots with that lens in daylight, incandescent light and studio light.

Next we have to find out utility to read the created DNG reference files and derive correction curves to remap the colors of other images to neutralize the color cast consequent on using this camera-lens-lighting combination.

 

[Asher Kelman]

So we import the .DNG file to the Xrite Colorchecker Passport utility that comes with a pocket size version of the color checker in a hard plastic walle-sizedt flat case. It opens up and the miniature card can be used instead of the larger regular sized card. There are also other nifty color cards there we can touch on later.

There are also other sources for the software. I will try to add a link.

Here the image is not recognized by the software so it cannot automatically extract the color data from the respective colored squares.

It turns out that our picture is at an angle!

So we just click on the corners and we get the go ahead to make the profile and it is saved right where we need it in "Camera Profiles" which Adobe ACR in Photoshop and Lightroom knows to find.

 

[Asher Kelman]

I will shortly show how these profiles can be used in two checks of the mouse to correct one's pictures.

Let's whip back to reality for a moment. The minimum you need is a matched set of camera and optics from the same MFR and a white balance card or diffuser and don't ever change color using the sliders for correcting color. These should be avoided like the plague until you have confidence as to simple, reasonably accurate color reproduction. The cameras of the last 10 years are pretty well perfect for almost everything, except you need to include that WB card in all your sets of pictures for a new set of lighting!

If you don't have these profiles, then better stick to the MFR's own
lenses. Then all you will need is to include a neutral white balance
card, such as WhiBal™ from Michael Tapes or else include a white card
or diffuse white light using a diffuser over the lens or or a white
balance lens cap style diffuser gives perfect jpgs out of the camera!

​