Test Your Correction Skills!

by Dan Margulis on September 24, 2020

If you’d like to check out how your color correction skills stack up to those of others, including some top professionals, my online discussion group recently finished a series of case studies in which group members were asked to submit their versions of some images chosen to be at least mildly challenging/interesting.

We did one of these exercises per week, for eleven weeks total. We didn’t tell the general public about it for fear of getting more entries than we could handle. But all the files are now accessible. You can read the text descriptions, but you technically have to join the group to access the images. It’s free, spamless, and cancellable whenever you like.

Here’s how it worked. An Italian member wrote me offline asking help with a photo of a brilliantly red carnival costume and mask. His problem was, it had to be printed in a book, and there is no way to achieve such vivid reds in any CMYK, let alone the one he was stuck with. And he is a photographer, not a retoucher, and so has not seen this issue many times.

I thought it would be a good exercise for the group as a whole, so I posted the RGB original and asked for people to send me their best CMYK efforts offline, together with an explanation of the procedures they followed. I then posted them and we had a good discussion of technique, some clear favorites, and requests for more such exercises. I suggested, and the group agreed, that we might as well accept that a lot of us are stuck at home with a lot of time on our hands, so that now might indeed be a good time to have such a series.

I therefore put together a series of ten original images, and each Monday I would release one. Those wishing to participate had one week to submit their entries offline, sRGB being the designated colorspace in all cases. The following Monday I would post them at the same time as I released the next one in the series.

The eleven studies drew between 21 and 30 entrants apiece. They were identified by number only without names attached (although some members identified themselves during subsequent discussions). The order in which they appeared was determined by random-number generator, since there is no better way to make one version look good than by sandwiching it between two bad ones. In addition to the online posting, I provided a downloadable .zip file containing all versions, for those wishing deeper understanding.

For each study, I quickly chose (before posting) what I thought might be the five best entrants, and averaged them into a “par” version, each of the five being weighted 20%. You may be aware from this blog that I am a big believer in this kind of blending. And if you look at these results you will be, too: everyone agreed that most of the time the par was better than any of its five parents.

Once posted, I stepped aside for a couple of days so that others could start the discussion. Within a couple of days, I posted a full analysis, discussing the strengths and shortcomings of each version and why some techniques proved successful and others not.

Here’s the announcement of the first of my exercises (reminder, anybody can read this and subsequent text messages, but to see the high-res images you need to sign up.)

The ten images I chose were selected for their diversity, and were ordered logically for the lessons to build on one another. Portraits, landscapes, flowers, night shots, scenes with action. Some were good for the workflow I advocate in Modern Photoshop Color Workflow, others less so. Some were pretty good out of the box, others had lighting issues. Eight were shot with respectable cameras, in six of which the raw capture was available. Since this was supposed to include work a retoucher might get in the real world, there was also one iPhone capture, and one desktop scan of an old, faded print. Here’s the list, starting with the one coming from the Italian photographer.

Carnival. An individual of unidentifiable gender wears a festive, floor-length gown and mask, brilliant red with yellow accents. Unfortunately, it is to be printed in a book, so it must be converted to CMYK, where it is not going to be possible to achieve such an intense red. You are given the CMYK specification; your mission is to make the costume convincingly colorful while retaining detail.

And now the set of ten selected by me, final product always sRGB.

Veiled Bride. A partially hidden face, a brick-wall background, a neutral gown and a lack of strongly colored objects come together as a recipe for boredom.

Niagara Spray. Another female portrait, the counterpart to the last one. This time, instead of being a distraction, the background is all-important, as the subject gets drenched by Niagara Falls.

Cinque Terre. A scenic hillside village in Italy, full of faded pastel buildings, with the sea in the background. Everyone agrees that the color has to be pepped up, but how far should we go?

Colosseum. A challenging night shot of Rome. How do we direct attention to the Colosseum, with so much going on elsewhere?

Panama 1978. A scan of an old print, faded. The print hasn’t been physically damaged, but the photofinishing of the time leaves a texture that needs to be addressed.

Monument Valley. Typical fodder for the workflow described in my book. A desert scene, full of subtle colors that need waking up.

A Toast to Greece. 70 years after being scattered by World War II, a family reunites in its ancestral village. The composition is fine but it’s a night shot under harsh lighting. Participants judged this one the toughest of the set.

Seated in Grass. A test to see how well we absorbed the lessons of the first two portraits. This woman is a redhead, but it’s easy to lose that color. And she has freckles, how to handle them?

Adirondacks. Autumn foliage, set off by flags of many nations, but with a twist: you’re given to understand that owing to unusual weather in the summer, this year’s display of color is the most spectacular in half a century. How to portray this without making it look artificial, or making the reds of the trees brighter than those of the flags?

Red Rose. The bookend to the first example, an image entirely about shape in the color red, this time, happily, in RGB. This is a good test of channel blending skills.


My update of M.E. Chevreul’s classic text On the Law of Simultaneous Contrast of Colors is finally available online. It was printed in late January; members of my discussion group were able to order it direct from the pressroom, which they did in surprising quantity. Our first shipment to Amazon sold out in four hours. The stock has now been replenished.

By reputation, Chevreul’s book belongs in the library of anyone interested in color, but it was published in 1839 when he couldn’t include serious graphics. And, although he tried to discuss every form of visual art that then existed, photography didn’t make the cut. I’ve supplied these things, among others, making it a joint effort between us rather than a mere translation and rewrite.

This is hardly a complete description. For that, check out my previous post, which offers the book’s Synopsis of Contents and many other goodies. I hope you’ll give us the chance to expand your horizons, and that you’ll agree that this was a book worth waiting 180 years for.


This is a pre-announcement of a book that is about to come on the market. You can’t order it for a few days yet, but you need to be on the lookout for the offer, because it’s going to be time-limited. After that, it will be available only on Amazon, which sometimes runs out of stock temporarily when a book is popular. This one appears to be.

What is it? Merely the finest practical work on color ever written. For once, I am not being egotistical. Rather, it is the considered judgment of history—nearly two hundred years of it.

Available for order now!

Available for order soon!

The French chemist M.E. Chevreul has regularly appeared in my previous books. In CC2E, I appointed him an honorary beta reader, and quoted him at length fourteen times, mostly in dialogs with other beta readers. His ideas sounded very modern, which is pretty good for words written in 1839.

His classic book on color strongly influenced the development of Impressionist and subsequent painting, but he introduced philosophies that are valid for all the visual arts. So it offers sections not just on how to use color in painting, but in tapestries, carpets, furniture, mosaics, churches, museums, apartments, formal gardens, theaters, maps, typography, framing, stained glass, women’s clothing, and even military uniforms.

Not, of course, photography, for when he wrote the daguerrotype was just being perfected. Nor web design. Instead, he describes problems we rarely encounter today, and then offers proposed solutions. This is a most useful exercise. If you aren’t able to predict what colors are most useful in, say, decorating an apartment that has no electric lighting, well, you should be.

Chevreul got into color in his 40s, by royal command. The king was dissatisfied with results from the Gobelins tapestry works, and blamed them on poor dyes. He hired our author, who was arguably the leading scientist in France at the time, to straighten things out. Chevreul did his testing and found out that certain dyes indeed were weak, but that the black, a particular target of criticism, was fine. When parts of a fabric dyed with that black, however, lay next to other parts that were dyed dark blue or purple, the black seemed weak and reddish. Chevreul called this misperception simultaneous contrast. Others had hinted at the effect before, but Chevreul defined it, as well as what he thought its ramifications were.

The resulting book got worldwide acclamation but there is doubt as to how many people actually read it. Chevreul, though a great scientist and an incisive observer of the arts, was a terrible writer. Furthermore, when the book made it into English 15 years later, it got a dullard of a translator who knew nothing about color. I publish a contemporary (1855) review from a scholarly journal, which stressed the importance of the book, but added, “We cannot forbear stating that justice is not done to Chevreul in the present translation. It is awkward, inelegant, often barbarous in style, and sometimes quite unintelligible.”

Yet this barbarous translation is the only full one we’ve had to deal with for the last 175 years, and the only one available for purchase (heavily abridged, yet) until next week or so. The best that can be said is that its title: The Principles of Harmony and Contrast of Colors, is a bit more descriptive than Chevreul’s De la Loi du Contraste Simultané des Couleurs. My new version, for better or worse, restores the original title: On the Law of Simultaneous Contrast of Colors.

I do not bill it, however, as a translation. Today books like his go through copy editing first, but his didn’t, and there are many stylistic faults and unclear sentences. I have acted as an editor to correct these deficiencies. Still, the text is recognizably his: the only stuff deleted is incontestably irrelevant today.

But his words comprise only two-thirds of the text. The rest is my commentary, needed to update what he was saying for modern needs or to point out areas where time has called his teachings into question. And naturally I have a lot of comments about the meaning for photography, although much of the time I discuss paintings, and how their lessons impact photos today.

In doing this, I revert to my customary method of showing alternate versions of images. This time, though, many of the images are paintings. I show how, Renoir, say, chose a certain color of clothing for a subject, and what would have happened if he had chosen something else. And I point out the obvious, that in many photographs it is permissible to change color of clothing, too, and I offer examples of when it makes sense.

Most of these comparisons show that the famous painter made the right choice, but not always. In a book like this, color graphics are crucial. Chevreul knew this, of course, and tried desperately to get them included. Those few he got in were primitive by our standards and cost a fortune, given the limitations of 1830s technology. I’ve added quite a collection, as follows (note: when there are, say, four variants of a given image, it counts as one image, not four)

Art that itself demonstrates a point about color usage:
Paintings: 40
Photographs: 42
Corporate Logos: 2
Weavings (tapestry, furniture covering): 4
Digital paintings: 2
Posters: 3
Stained glass: 2
Wallpaper: 2
Map: 1

Other artwork:
Artificial graphics to show points about human vision: 28
Photos, paintings, and linework used as illustrations only (no point being made about their own use of color): 41

To further aid in your decision of whether to get this book, here are some interesting pop-up links:
*The book’s front and back cover
*The Synopsis of Contents
*My Foreword
And two more, in response to those wanting more details on which artists were getting coverage:
*Dramatis personae: as Chevreul and I are both big name-droppers, this gives biographical information on the 172 artists, scientists, engineers, politicians, etc. who populate the pages, with an explanation of where they are discussed.
*Born at a time when the human life expectancy was about 40, Chevreul lived almost to 103. He therefore was alive before the French Revolution, and after the births of Franklin Roosevelt and Winston Churchill. I offer a timeline of his lifetime with respect to politics, science, culture, and his amazing career.
*And, if you want to download a zipped package of all five of the above, here it is.

My normal readership can’t be expected to have much interest in a book in which the word Photoshop never appears. On the other hand, my previous books require a certain computer proficiency, whereas this one is accessible to anyone who likes color, whether they know how to pick up a mouse or not.

So we launched a trial balloon. I announced the book in my discussion group a few weeks ago and offered to take orders for immediate shipment from the printer as soon as the books were bound. This resulted in more than five times as many orders as we anticipated, many for multiple copies. The rest of the books are now on their way across the country.

Anyhow, here’s hoping you find the project as interesting as I did. Keep your eyes open for the sales announcement!


Applied Color Theory Group Finds a New Home

by Dan Margulis November 24, 2019

The Applied Color Theory list, which discusses matters of interest to my students, friends, and colleagues, has been operating since 1999. For almost the past twenty years it has resided at yahoogroups. After many years of deterioration, yahoogroups recently decided it would now become e-mail only, no images allowed. We have therefore moved the group […]

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Unexpected and Unpleasant Surprises (The MIT 5k dataset 9)

by Dan Margulis September 2, 2019

Previous postings evaluating how the Picture Postcard Workflow did compared to the retouching team on the MIT dataset established the obvious, that neither PPW nor any other workflow is the perfect solution every time. The question is, how do identify when PPW shouldn’t be expected to be better? Sometimes the image simply doesn’t have enough potential for […]

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Copyright: When two photos are too close for comfort

by Dan Margulis April 15, 2019

The college basketball playoffs in the United States have just ended. Basketball sets the theme for the apparent resolution of a longstanding issue involving photography, and by implication many other areas of design. If without permission, you re-use someone else’s photograph, you may be looking at paying for copyright infringement. This is assuming that you […]

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R.W.G. Hunt 1923-2018

by Dan Margulis February 26, 2019

I recently learned of the loss of an outstanding contributor to the practical side of color science. Robert W.G. Hunt died in October at age 95. He was a prolific writer, but he is best known for his massive text The Reproduction of Colour, now in its sixth edition. Most of it is quite geeky, […]

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Image Distribution Surprises (The MIT 5k dataset 8)

by Dan Margulis December 7, 2018

The MIT study offers a unique opportunity to study the distribution of images. Most of the images that I and other authors collect for our own purposes test or prove a certain point. The MIT dataset, on the other hand, simply gathers together images that might be worked on professionally, whether dull or interesting, without […]

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Introducing the PPW Tools Panel, version 5

by Dan Margulis June 2, 2018

The Picture Postcard Workflow is more than a decade old, but it never really caught fire until the time of Photoshop CS5, when an imaginative Adobe product called Configurator allowed us to store actions in the form of a panel for easier use. Even in those prehistoric times, PPW was highly automated, so assembling its […]

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When Is There No PPW Advantage? (The MIT 5k dataset 7)

by Dan Margulis March 27, 2018

The arsenal of weapons that we can deploy against recalcitrant images is powerful and impressive. When used prudently, that is. Assuming that because you have them you are guaranteed to create stunning imagery tempts you to try too hard to make it so. When this happens, as we’re about to see, the weapons, including PPW, […]

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