Notices:Adobe and Photoshop are registered trademarks of Adobe Systems Incorporatedin the United States, Australia, and/or other countries.Mac and Apple are registered trademarks of Apple Computer Inc. registered inthe United States, Australia, and/or other countries.Windows and Microsoft are registered trademarks of Microsoft Corporationregistered in the United States, Australia and /or other countries.All other trademarks are the properties of their respective owners.Lobster and LobsterDemo are solely the product of Free Gamma Pty Ltd.No person, company or product mentioned by name in this text has any connectionwhatsoever to Lobster, LobsterDemo and/or Free Gamma Pty Ltd.The exception is Ian Lobb, the developer of Lobster, the author of these notes andthe founder and owner of FreeGamma Pty Ltd.Lobster, Lobster Demo and Free Gamma Pty Ltd and any, or all, its employeescannot be held responsible for changes to digital files from the part or full use ofLobster, LobsterDemo and/or any other products or advice of Free Gamma PtyLtd. Lobster, LobsterDemo and Free Gamma Pty Ltd are not responsible forthe content of recommended Internet sites.

Free Gamma Pty Ltd asks all users of Lobster and/orLobsterDemo to make new copies of their files for use with Lobsterand/or LobsterDemo.Unless users of Lobster and /or LobsterDemo have back-up copiesof their files, they should not use Lobster and or LobsterDemo ontheir files.Lobster and/or LobsterDemo presumes an understanding of basicPhotoshop operations.

All rights reserved. Except for personal and individual study, no parts of these notesmay be reproduced without written permission from Free Gamma Pty Ltd.Free Gamma Pty. Ltd., Melbourne, Australia. These notes first published May 2006.

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In this article we look briefly at some of the parts of the ZoneSystem.We use some convenient Photoshop divisions for zones and seeif they are accurate for Grayscale images.We then ask how we can measure zones in RGB colour files.Finally we try to accurately expose for the shadows, developfor the highlights (a classic Zone System strategy) with aLobster RGB colour file and use Zone System values.

The Zone System has a long history in analogue photography.This essay is not going to repeat a description of the Zone System that is availableelsewhere. There are classic Zone System texts that are the basis of the Zone Systemindustry.These texts are particularly valuable to understand the Zone System as outlined bysome of its early proponents:

The New Zone System Manual, Minor White, Richard Zakia, Peter Lorenz.Morgan and Morgan.1976The Negative: Exposure and Development, Ansel Adams. Morgan and Morgan.1968

While studying the Zone System, consider it to be made up of several stages:1. Tonality is divided and named. The total range of tonality from black to white

is divided into a number of distinct tonal steps called zones by thephotographers and scientists who developed the Zone System.Zone 0 is absolute black. Zone X is considered white (Zone System literaturealways name zones with Roman numerals.)

2. There is testing. There is a personal choice of B+W film and film developers,followed by their calibration. Film development methods, light meters, printdevelopers, papers, enlarging sources, thermometers etc. are included in thiscalibration so that various exposure and development choices will producepredictable zone values.Central to this testing is the establishment of a personal ISO for film, and aNormal development time where every EV (Exposure Value) numberdifference on your light meter is a difference of a zone in a print.

3. There are visual skills in the field. There is a previsualisation of the subjectmatter so that zone values are assigned to values in the subject matter.

4. Test outcomes and skills are combined and applied. The Zone Systemcontinues beyond previsualisation as light meter readings of the subject matterare made.The difference between the contrast of the subject matter as revealed by lightmeter readings, and the contrast of the subject in the previsualisation isreduced by choosing a Zone System film exposure and development plan.Typically, on B+W panchromatic film, shadow values are exposed toreproduce previsualised values, and the film is developed to a chosen gamma

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so that the highlight values also match the previsualisation. This is a preciseapplication of the approximate rule-of-thumb known as exposing for theshadows and developing for the highlights.

5. The Zone System values are also used for discussion.Values in black and white and colour prints already represent zonal values.Skilled Zone System users can discuss the zone values in a print. This makessome technical and aesthetic discussions possible that would otherwise be verydifficult. As well, the appearance of the anything in the world may bedescribed by those values. Skilled Zone System users can describe theshadows of a physical tree that already appears to them as zone IV (forexample).

In colour analogue photography, the nature of materials meant that there was neverthe same flexibility in a system of exposure and development that is found in B+Wphotography. Nevertheless the Zone System helped many analogue photographersunderstand the necessity for an exposure based on the sensitometry principles that arethe Zone System.Those familiar with the Zone System found that they were able to describe values incolour photographs by using zone descriptions. There are still zone values in colourand B+W prints, and in a previsualisation of the real (colour) world.

Zone System values are established historically and they are a working, livinglanguage. You would imagine that digital photography would be able to make gooduse of the Zone System language. As we know digital photography has produced aplethora of digital products and digital ideas. Some of these ideas are misusing theZone System tool.

ZONE SYSTEM LANGUAGEThose attempting to introduce the Zone System into digital practice needed towork out a method for measuring zones.This usually began by using either K values in a Grayscale file or RGB values inunsaturated RGB files. OFTEN ZONES ARE DIVIDED FOR CONVENIENCE,RATHER THAN ACCURACY. An example of this type of convenience is wheneach zone is designated as worth 10% K value. Or if using RGB values each zonewould be worth 25,25,25 RGB values. (See below).

So Zone 0 (black) would be 100%K to 90% K,Zone I would be 90% K to 80%K,until we reach zone X @ 100% K.

If counting in RGB, Zone 0 would be 0,0,0 to 24,24,24.But as you can see the arithmetic gets a bit messy because this only takes us to250,250,250. But.Some Photoshop users have looked at the 10 x 10 expanded grid in Curves and said,There are 10 grids, and there are 10 zones. What a wonderful coincidence. The firstsquare starts with the start of zone 0. Therefore the last square marks the transitionfrom zone XI to absolute white: zone X. It seems too good to be true.

Later we will see the difficulty of using this idea with colour files. But lets beginwith a black and white file, and convert it to RGB mode so that we can use RGB

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figures throughout this article. You can easily try the example below with K values of100% and 90% too.We configure the Curves dialogue box so that black is in the bottom left.An RGB value of 25,25,25 would be represented in Curves at A in the figure belowif the RGB Working Space was Ektaspace PS 5,J.Holmes (See Manual One:Preparation). According to some of the people who divide up the zones into Curvegrids, K and RGB values and this is where zone I would begin:

Zone I has a particularly important place in Zone System history. For thosephotographers who ran film calibration tests, it was the basis of many film ratings.The description of this zone in Zone System teaching IS particularly clear and precise.It is the first tonality where you can JUST see a difference between that zone andblack. The very first tonality!It is easy to see whether this would still true in a world where Curve grids equalzones. Fill an RGB file with RGB 0,0,0 and then paint some shapes with RGB25,25,25.This is obviously NOT the first discernible difference from black. And RGB 25,25,25is the darkest part of the value that some people regard as the digital zone I.So we have the somewhat ridiculous position of having values in the digital zonesystem different from the values in the analogue, historical zone system.Two languages pretending to be one.

If you want to trouble yourself even further with this, make a new RGB file whereyour profile in the New File dialogue box (File> New) is ProPhoto RGB fill withblack 0,0,0 and paint some shapes with RGB 25,25,25. Now make another new fileand in the New File dialogue box choose sRGB as your profile and paint with25,25,25 again,Note that the visual difference between the dark values and black is not equalbetween these 2 RGB profiles. Zone I means different things in different RGBworking spaces. Not satisfactory!And this is only the darkest zone. There is hardly a co-relation between the other gridvalues and the traditional Zone System values.It is not correct to try and use the Zone System language in a cavalier fashion.

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If we categorize zones according to the divisions in the Curves dialogue box we willnot be using the traditional zone system language. We will be inventing a newlanguage. We should not pretend it is the same language.

Using 10% K steps or 25,25,25 RGB steps, or the Curves grid as a way of definingzones has these 2 problems for black and white imagery:

1. These values or grids do not divide tonality in the same way as the pre-existantZone System.

2. What these values or grids represent varies as the Working Space changes.Assigning any RGB number or K number to a zone is contingent upon manyfactors among them is the choice of the Working Space. But every zone is acarefully defined abstract with qualities that remains separate from changescaused by Photoshop configurations.

CURVES, RGB COLOUR IMAGES AND THE ZONESYSTEM.(Windows users please read Control /click where the text gives Command /click.)Here are three 100% saturated, 100% bright, colours.They are RGB: 255, 0,0 0,255,0 and 0,0,255. These figures are the brightness valuesof their channels.

These have been Command clicked to place them on the curve of the Curves dialoguebox.

Their positions have been coloured so that you can see where each of these particularcolours appears on the RGB curve in the chosen RGB Working Space (EktaspacePS5, J.Holmes., see Manual One Preparation).

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Obviously they are not positioned on Curves because of an average of their brightnesschannel values or they would each be placed at the same point.Even though their brightness vales are the same, Curves does not rank the brightnessvalues equally instead Curves ranks them by their luminosity values.Luminosity appearance is the closest we have in RGB to the appearance of values aszones. (Looking at colour files in K values does not work for zone designation.)

IN A COLOUR RGB FILE, WITH MORE THAN ZERO SATURATION,PHOTOSHOP BRIGHTNESS CANNOT WORK BY ITSELF TO MAKE A ZONESYSTEM DIVISION.

WE WOULD NOT PREVISUALISE THESE THREE SAMPLES AS THE SAMEVALUE IN A ZONE SYSTEM PREVISUALISATION.

HOW THEY SIT ON AN UNEDITED RGB CURVE IS PHOTOSHOPSINTERPRETATION OF THEIR LUMINOSITY -OR -PHOTOSHOPS INTERPRETATION OF THEIR ZONE VALUE.

Curve values are the closest Photoshop RGB values that we have as to how we wouldplace the relationship of these three values as zones. In Curves we see their luminosityvalue. Luminosity takes into account Hue, Saturation and Brightness when assigninga value. And these factors are weighed with human vision factors. Just likea previsualisation!.

A luminosity read out is a necessary first step if we are going to assign zone values toRGB files. There is much more on this in the manual Luminosity

We have a luminosity histogram in Window> Histogram.We have Control points in Curves that show luminosity values.But we do not have any other ways of making a luminosity read out.How then, are we going to accurately assign zone values if we cannot read values thatrelate to human vision ( luminosity values)?

The Luminosity layer in a Lobster file DOES enable you to read out luminosityvalues using the Info palette - - you can read them out as RGB values. As each RGBnumber is the same (the Luminosity Layer has zero saturation) any of the RGB valueswill work as a luminosity value.Your RGB Working Space automatically modifies the luminosity representation on aCurve. AND IMPORTANTLY, THE CONTOURS OF RGB VALUES IN ALUMINOSITY LAYER ARE THE CONTOURS OF ZONES.MAKE A SELECTION OR A MOVE BASED ON LUMINOSITY LAYERVALUES AND YOU ARE ESSENTIALLY FOLLOWING THE SAME RULESTHAT DIVIDE UP ZONES.

USING ZONE SYSTEM STRATEGIES IN LOBSTERVariable B+W film development produces a variable contrast.The oldest Zone System strategy is finding a STRUCTURED way to use the variablefilm development of black and white film.This is how film can be exposed to lock-in a shadow value and film developmentaltered to produce the desired highlight value.

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With Lobster this strategy may be accurately extended to include colour RGBfiles. Please note this strategy is for Lobster files or B+W files. It is differentfrom using Curves or Levels in regular RGB colour files at any mode. See thedownload Levels in Regular RGB files @ Luminosity mode.

STEP ONE: Make a Lobster copy of your RGB file.STEP TWO: Open Curves, grouped with the Luminosity Layer and Command Clickon a value that represents the most important shadow area to you.STEP THREE. Command click on a value that represents the most importanthighlight area to you.STEP FOUR Control / Tab to cycle through the Control Points and return to theshadow value point.STEP FIVE Use the arrow keys on the keyboard to adjust the shadow value as youwish. (Sort of: Expose for the shadows.)STEP SIX Control / Tab to the highlight value (which has been accurately lockeddown) and use the keyboard arrow keys again. (Sort of: develop for the highlights)Please note that as you use the Luminosity layer to adjust values you are movingvalues that relate directly to human interpretations of tonality.

EXAMPLE:WE CAN EXTEND this idea of taking care of the shadows first and then adjustingthe highlights to more than two values.If this were B+W film and we were making a Zone System exposure, we would makean exposure based upon a light meter reading from an important shadow areaThis could be value A (Taking a meter reading from that area and underexposing it2,3 or 4 stops depending on how we wanted the shadow to look).

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We would also take a light meter reading from D. We would see how that would lookwith Normal film development and adjust the film development to match ourprevisualisation. Maybe C would end up being adjusted by a filter and maybe withB we would have to trust out choice of film and film developer.Because the Luminosity Layer enables us to 100% accurately assign positions on aCurve here are some simple steps with a colour RGB Lobster file:

STEP ONE: On the Luminosity Layer of a Lobster version of this file, make a Curvesadjustment layer that is grouped with the Luminosity layer @ Normal mode.(You can choose the Adjustment layers from the icons @ the foot of the Layerpalette.)

STEP TWO: Command click on shadow A to lock it downThen lockdown B, C, D.

STEP THREE: These values are now accurately chosen and locked down. Doing thisin a Lobster file has unprecedented accuracy and control for an RGB file.

STEP FOUR: You can move each of these shadow and highlight values as you wish.Control / Tab will enable you to move through the lock-down points and adjust themwith the keys on your keyboard.

It seems overkill to give a screen shot; nevertheless:

Photoshop allows you to have up to 14 lock-down points on a Curve.Each adjustment on the Luminosity Layer follows the same boundaries that definezones.

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ZONE MASKSAny selection that you make in the Luminosity layer using the Magic Wand,Select>Color Range or using Threshold, Levels, Curves etc. as a first step will befollowing traditional zone boundaries.You can edit selections by using any of the Photoshop tools or dialogue boxes thatallow you add, subtract or intersect with selections.Or you can save a selection and make any sort of move upon the alpha channel.These alpha channels can of course be loaded a masks at any time in your editing.

Lobster has many real Zone System moves built into it by virtue of using aLuminosity Layer whose values are based on human vision.Nevertheless you may not like Lobster and wish to use another product.Make sure there is not a division into zones based on brightness in colour files.This would make nonsense of the zone system.Make sure that Zone I is not designated as K 90% or RGB 25,25,25. That is not usingZone System language correctly.

You dont really need to know at which RGB or K value something becomes ZoneVII or any other zone. And this is flexible anyhow depending upon your WorkingSpace.But you could be aware of the Zone system language so that you can say Look at thedelicate texture in the brightest part of zone VII and other Zone System users knowexactly what you are saying. That is unless there is a haphazard definition of zones inthe digital realm.

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1p1.doc.pdfThe zone system2.pdf