Discover Fixel Zone Selector 1

Fixel Algorithms Zone Selector

This is a guide that introduces you to Fixel Algorithms Zone Selector 1.

In order to understand what this plug-in does and how it helps us, we have to stop on two core points. The first one is that Fixel Algorithms affects the image’s luminosity and the second one is Ansel Adams’ Zone system. So

Fixel Algorithms Zone Selector 1 is a plug-in that generates luminosity masks and is based on Ansel Adams’ Zone System

Luminosity and luminosity masks

If you are a photographer then you know that every object is reflecting lights in different ways. The lightness or the darkness of this reflection gives us lighter or darker results.

Easily shown, if you take a look at this picture of the Royal Palace taken in Monza, Italy, you will notice that the green of the leaves, grass and trees in the background looks different depending on how it reflects light.

Some greens look lighter and some look darker. So there is a range of luminosity around the green colors that goes from darker to lighter. At times when contrasts are very intense, more than in this picture, the extreme levels of luminosity, the lightest and the darkest, might be very hard to control. That would result in a lack of details.

Again, if you have spent some time in the photographic world, right now the High Dynamic Range (HDR) bell should ring very loudly.

If you have never heard of it, HDR is a photographic technique that consists in taking different pictures of the same area to include all details that the brain can adjust while looking at a scene, but that the camera can’t, especially if it is oriented towards a very contrastful picture with wide tonal ranges.

As you know, our brain adjusts the luminance of the subjects in front of us no matter the levels of contrasts in some scenes, so that we can catch all details. This does not work as easily for your digital camera. What is done by some professionals then, is: the photographer takes different pictures of the same subject with different exposures, each adapted to a specific part of the subject it-self. Finally, composing the pictures together in post-production, and picking the best exposition for every part of the subject to blend it in one single picture, the final result emulates the adjustments made by our brain when we looked at that scene in real life.

A quick look at this example with two exposures, one for the sea and one for the sky finally combined in one picture where everything is exposed the way eyes saw it, might help you follow me. The picture is taken in Stockholm, Sweden


One of the risks of this technique, is that if you are too zealous in hunting the details, you will end up with a non-realistic fairy tale-like result that does not fit all spectators’taste. With digital photography, viewers are getting more and more keen to these artefacts, spotting these solutions easier than you might expect them to.

HDR is somthing that, if not done well, might degrade the quality of your works.

So one finesse for whoever is using Photoshop, is to furtherly work on the adjustment of each and every part of the picture with a luminosity or luminance mask, in order to have a better control of your results. Masking in Photoshop is a non destructive way to edit selective parts of your pictures, allowing to control the intensity of the results in post-production.

Now, HDR composites and luminosity masks work hand in hand. But I would like to have you thinking about the huge amount of time both the shooting and the retouching take when we create HDR pictures.

Luminosity masks are created using the channel palette in Photoshop. It is such a time consuming process that some people make a living by creating actions for luminosity masking.

But then Fixel Zone Selector 1 came, and bravely reinterpreted Ansel Adams’ Zone System to help us saving time without compromising on quality. What’s then, in this Zone System?

Ansel Adams’ Zone System

Ansel Adams is a name that all professional photographers know and respect. He’s one of the most influencing fathers of the art it-self. Even if he photographed with analog cameras and even if he photographed in black and white, much of his study and production around photographic techniques are still relevant even for digital photographers.

Now I have a scenario in front of me: you who read either know the Zone System very well and have no need to be schooled on this, or you have no idea about it and you are eagerly waiting to learn more, but expect me to make it as simple as possible.

For both of you and the sake of your time, I will try to make it very brief, but I really need to underline that it is a subject worth more of the space I allow me to give it. There is a lot of production on the internet around the Zone System, so I will stay on what is relevant for digital color photography and rely on your curiosity to find more.

You digital camera has something that somehow already works having this system on mind. You might call it the plus/minus button or the light compensation, but it is a fuction that allows you to lighten or darken your picture. If you know how your camera is built, you know that it tends to interpret scenes with a huge amount of white or with a huge amount of black, as scenes with a huge amount of 18% kodak grey. That is a compromise that helps the camera render skin tones correctly. It is also a compromise that affects your results and you know that if your whites or your blacks look too grey, then it is the light compensation that can come to help. It might look different depending on the camera you use, here some examples


You can go up or down with the light compensation, plus or minus. The plus side tells the camera in a way to make the white whiter, and the minus side tells the camera to make the black more black.

Consider a painter: if a painter is creating a scene and he wants to make it darker, he or she will add the same amount of black to all colors to make them progressively and proportionally darker. If he or she wants to make it lighter he or she will add the same amount of white to all colors to illuminate the scene.

If you check these nuances of blue, where I did put black and white on the extremes, you can see how they gradually go from a darker one to a lighter one.


When you take a picture, that colors are darker may likely depend on the fact that that part of the picture is in the shadow, as much as the lightest ones are lighter because they are more exposed to the light. The range of colors can be much wider than in my example and can give us real headaches in tricky situations.

Now Ansel Adams was a researcher, not just a photographer, and was already concerned about this issue. Back then things were solved in the dark room, with a painful and time taking work.

Adams had divided levels of exposure that might throw off your camera in eleven standardized zones, and keep on mind that the core factor here is luminosity. We are working on different ranges of luminosity. Each of Adams’ zones refers to a specific tonal scale, having 18% grey in the middle.

In jargon we say every zone is + or – 1 stop with 18% grey on V. The System Zone is normally expressed in Roman numbers. V is five, go figure out the rest. Zero is pure black and ten is pure white.

Let’s try to sum them up in an easy table


[source: Wikipedia]

Now if we want to apply this to the blue colors, looking back at my former picture, you can apply the table this way:

I am being very picky now when placing my black and my white, as they are textured.

If we now look at our plug-in, Fixel Zone Selector 1, there you can see how the interface looks like


and it should look very familiar now. So what are we doing here? Basically, every time we choose a zone, we select all areas in the picture that would fit the description of the tonal zone of the chosen number. When you will select a number, the button that shows “comp” will turn into “mask” and the picture will show a masked selection of the given tonal range.

In this way you can adjust even the trickiest situations just going through the selections of tonal ranges in Fixel Zone Selector 1 and give your picture that feeling and dynamic it had when your eyes perceived the subject.

In the following video I will show you very quickly how it works on a night picture of Rome’s Pantheon:



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