Category Archives: Photo editing

Review: Cokin varicolor

A varicolor really starts to shine when you use it on seascapes.

Wouldn’t it be nice to have a real Photoshop filter that screws onto the front of your camera lens and just makes color look better? If landscapes, architecture, seascapes and vehicles are your thing, there is such a filter: the varicolor polarizer.

The varicolor used to make drab dirt and ordinary foliage more interesting
The varicolor used to make drab dirt and ordinary foliage more interesting

The varicolor consists of two tinted polarizers rotated 90 degrees from each other. Thus light is colored by one or other of the two tints depending on its phase… um, that means absolutely nothing to most people, so here’s a better description:

Most landscape scenes have two types of light: direct and reflected light, such as

  • Direct light from the sky vs light that has been reflected from water
  • Direct light from the sky vs reflected light coming from the ground.
  • Reflected light coming from two very different surfaces, typically shiny vs rough.
  • Highlights and reflections vs non-highlights from the same metallic object (typically vehicles).

The varicolor filter will separate the direct and reflected sources and tint them via two different colors. The amount of tint can be varied by simply rotating the filter.

Many photographers assume a varicolor is simply a variable warming and cooling filter, and the packaging on one of the main suppliers of varicolors, Cokin, does little to kill this miss-assumption.

Cokin Packaging, showing a varicolor being used as q variable warming/cooling filter. This is not how it is usually used!
Cokin Packaging, showing a varicolor being used as q variable warming/cooling filter. This is not how it is usually used!

It is true that a varicolor filter can be used just for global warming/cooling, and can totally change the lighting.

Blue/yellow varicolor, used to turn a blue sky (left) into a magenta, orange and violet sky.
Blue/yellow varicolor, used to turn a blue sky (left) into a magenta, orange and deep blue sky.

More usually though, you make slight changes to the ambient. You are more typically not trying to tint the scene so much as tint the direct and reflected light via two complementary colors ( typically, but not always, warming and cooling) to get a visual separation between the two.

In this series of shots, the sky light is rendered bluer, and the ground and foliage yellower
In this series of shots, the sky light is rendered bluer, and the ground and foliage yellower
The cool thing about these photos is that there is almost no color correction going on: the photos pretty much looked like this from the camera live-view when I took them!
The cool thing about these photos is that there is almost no color correction going on: the photos pretty much looked like this from the camera live-view when I took them!
In this scene, the small puddles could not be seen, the ground was a uniform grey, the sky an overexposed solid white and the foliage the same shade of green throughout. All this changed when the varicolor was used, and I saw the change directly through the camera viewfinder, rather than having to do it all in post.
In this scene, the small puddles could not be seen, the ground was a uniform grey, the sky an overexposed solid white and the foliage the same shade of green throughout. All this changed when the varicolor was used, and I saw the change directly through the camera viewfinder, rather than having to do it all in post.

Buying a varicolor filter

Varicolor is an effect most suitable for wide angle lenses. There are two companies that sell wide angle varicolor filters, Singh-Ray (‘gold-n-blue’) and Cokin (P173). Hoya also do them, but in smaller sizes (typically 58mm) that are not really useful as we are nowhere near wide angle diameters.

The Singh-Ray is priced too high for most people’s pockets. The Cokin is about 1/5 the cost and very affordable, but comes as a square cassette for the Cokin P Series holder rather than a standard 77mm filter thread (such as the one I need for my Tokina 11-16mm, a lens that suits a varicolor perfectly).

A Cokin P series filter cassette (l) and the standard 77mm circular filter format (r) most non-Cokin users would prefer.
A Cokin P series filter cassette (l) and the standard 77mm circular filter format (r) most non-Cokin users would prefer.

There is a third option: make your own standard varicolor filter, using a cheap Cokin P173 and an even cheaper no-brand circular polarizer filter.

Making a standard 77mm varicolor filter

The Cokin filter cartridge is easy to open (you just prise it open with a knife at one corner enough to get your fingernails in, then open it with fingers – it opens very easily as it isn’t glued down) to reveal a much more standard looking circular 75mm glass filter body. We next need a standard 77mm CPL (circular polarizing filter) to put the varicolor glass into. It has to be a CPL filter because like a varicolor, the CPL has to be rotatable on the lens for it to work. It also has to be a non-low profile CPL, for reasons we will see next.

The Cokin cassette opens easily. It is just held together by a series of plastic plugs, no clips/glue to overcome.
The Cokin cassette opens easily. It is just held together by a series of plastic plugs, no clips/glue to overcome.

When you take the varicolor filter glass out from the Cokin cassette, the first thing you will notice is how heavy and thick it is. A standard CPL is about 1.5mm thick glass. The varicolor is three times that: 4.5mm. In other words, it is half the thickness of a standard window pane!

That makes a kind of sense: the varicolor is two CPL filters, each with its own color filter added on, so we are talking x2 CPLs which takes us up to 3mm, and then x2 color filters on top of that. The upshot of this is that you cannot use a low profile CPL filter ring: it has to be full height.

Even with a full height filter, I had problems putting the varicolor into the CPL filter ring. The varicolor is just too thick! The only way to get it to fit was to reverse the filter retaining ring as shown below. The varicolor is about 2mm smaller in diameter than a standard 77mm CPL, and you can use that space by turning the retaining ring over so it goes down further into the filter, and just enough to become fully threaded into the filter body.

Top, the difference in thickness between a standard CPL and varicolor. Bottom, For a CPL, the retaining ring is screwed well into the filter. To get a varicolor into the same ring,  you typically have to reverse the retaining ring for it to screw in fully.
Top, the difference in thickness between a standard CPL and varicolor. Bottom, For a CPL, the retaining ring is screwed well into the filter. To get a varicolor into the same ring, you typically have to reverse the retaining ring for it to screw in fully.
My completed Cokin P173 Filter in a standard 77mm thread, ready to screw into my Tokina 11-16mm ultra-wide.
My completed Cokin P173 Filter in a standard 77mm thread, ready to screw into my Tokina 11-16mm ultra-wide.

Rotating the completed filter whilst looking through it at the sky, you will see the sky tint from bluish to yellow, going through a series of pinks and magentas at the midpoint. If you have any reflected light in the scene (coming from windows, water, or highlights on pretty much anything), they will take the opposite tint to the sky. This occurs because one CPL is tinting the direct (sky) light and the other one is tinting the reflected light.

Choosing the varicolor tint pair

The secret to using a varicolor is realizing that they move your overall white balance, and you need to fix this in post, removing any introduced color cast and pulling the varicolor effect back towards something much more desirable.

As well as the P173 (blue-yellow), Cokin also do the P170 (red-green) P171 (red-blue) P172 (pink-orange) and P174 (blue-lime). The p173 varicolor is the most popular because its two colors match the white balance temperature range. I’d be tempted to start with a P173, and chances are that it’s the only one you will ever need.

The Lightroom color balance slider, showing that color temperature is a variation between cold (blue) to warm (yellow). This color range is replicated in the Cokin P173.
The Lightroom color balance slider, showing that color temperature is a variation between cold (blue) to warm (yellow). This color range is replicated in the Cokin P173.

So, using the P173, you can tint the two light transmission types (reflected, direct) in a scene so one is warmer and the other is cooler. In the photos of the wood above, the light coming from the sun is cooled via the varicolor, and the leaves and foliage are made warmer. This creates a nice contrast between the two, and the lighting and reflected light thus become more prominent than it was on the day.

Using a varicolor

Although a varicolor can be used to give a nice warm-cool color balance differential between the sky and ground, its standard textbook use is where there is water, reflecting metal, or glass.

Effects of blue-yellow varicolor on water: yellow (left), no filter (center) and blue (right). This is as shot, no photoshop. A pretty strong effect!
Effects of blue-yellow varicolor on water: yellow (left), no filter (center) and blue (right). This is as shot, no photoshop. A pretty strong effect!

The above three photos were all shot with the same P173 filter, rotated to get the leftmost and rightmost versions.

Most people don’t care for this effect. Not only is the water overly tinted, every other color is way off via an undesirable cast. The effect puts a lot of photographers off, until you realize the secret of using varicolors properly…

The secret to using a varicolor is realizing that they move your overall white balance, and you need to fix this in post, removing any introduced color cast and pulling the varicolor effect back towards something much more desirable.

Setting the white balance (in this case by clicking the Lightroom white balance selector tool on the ground below the tree trunk to set it back to its original neutral grey) will also reduce the effect of the tint.

Yellow version pulled back via white balance correction. Much more subtle!
Yellow version pulled back via white balance correction. Much more subtle!

If you are shooting landscape, a bit of white cloud or grey ground will suffice to set white balance, but more generally, you need a grey card. If you don’t have one, an almost perfect stand-in is a square of card from an unwaxed, unbleached breakfast cereal box. The inner side makes a perfect grey card for the purpose of white balance. If you expect to be in direct sunlight, get a smooth stone or a bit of fine emery cloth and sand the grey side down for about a minute so it starts to lighten slightly. I’ve tested such a piece of sanded card against a calibrated X-Rite grey card, and the resulting color balance is consistently within 1% of the calibrated (and very expensive) X-Rite!

Varicolor filters and seascapes

A varicolor really starts to shine when you use it on seascapes.

The situation where a blue-yellow varicolor absolutely excels is when you need to take a photo of the sea on an overcast or very bright day. In this case, both the sky and sea will be the same grey (or blue-white). Grey on grey isn’t a very compelling color scheme. The grey light of the sky is at a different phase to the grey coming from the sea though, so using a varicolor we can save the day by creating a color separation where there was previously only grey. In fact, in this situation, the varicolor is a requirement to getting a decent shot unless you want to do some serious post processing!

In the shot below, I used the varicolor to turn the water blue, ignoring what was happening to the sky.

Out-of camera shot, initial varicolor
Out-of camera shot, initial varicolor. Lots of color separation, but also a pink cast

We now have some color separation between the sky and sea, but white balance has been totally destroyed and we need to reset it in post. We can either select the blue of the sea as our white balance point (which will warm the entire image towards sepia, and might have been appropriate if the sun was in the sky), or the grey of the sky (which will give us a blue sea and grey sky). Both will fix the issue, but will give us a totally different look. I want a blue sea, so have clicked the sky:

Changing white balance to tone down the varicolor: (l) making the sky grey or (r) making the sea grey.
Changing white balance to tone down the varicolor: (l) making the sky grey or (r) making the sea grey.

Tweaking the image further gives us our final photo…

Finished Seacape, with proper color separation between sky and sea.
Finished Seacape, with proper color separation between sky and sea.

In the actual scene, the sky and sea were the same color, and although this final version has been processed for exposure, I have hardly altered color at all apart from the initial white balance correction and lowering yellow from the foam. I left most of the color correction to my trusty real-life Photoshop filter – the Cokin P173.

Another cool use of the P173 is when you are using HDR photography. HDR will take the varicolor tints and overdrive them, giving you a dramatic effect.

Original Shots (top) and white balance corrected for grey sky and ready for HDR (bottom)
Original Shots (top) and white balance corrected for grey sky and ready for HDR (bottom)

When shooting HDR of fast moving water, it makes sense to use a fast shooting camera. The Sony A77 does 12 frames per second. That and its fast WYSIWYG live view make it perfect for landscape HDR, especially if like me you prefer to shoot hand held.

Final photograph: Robin Hoods Bay, North Yorkshire, England.  5 exposure HDR, rendered via HDR Efex Pro. Final correction (exposure dodge/burn) via Lightroom.
Final photograph: Robin Hoods Bay, North Yorkshire, England. 5 exposure HDR, rendered via HDR Efex Pro. Final correction (exposure dodge/burn) via Lightroom.

Disadvantages of the varicolor

As mentioned earlier, the varicolor is really two tinting CPL filters. It comes as no surprise then that the varicolor has such a strong color effect as it is really two filters, each with two elements (CPL+tint).

You will have the usual negative issues of stacking what is really two filters onto a lens, the biggest one being stop loss: you lose up to two stops of light. That’s enough to kill your autofocus even on a bright sunny day. Fast f2.8 glass is pretty much a must, otherwise its down to tripod and manual focus.

Vignette is another issue, so you may need to correct for that in post.

Finally, as mentioned earlier, a varicolor is seriously thick glass: 4.5mm, which is half the thickness of a standard window pane. On the bright side, such a filter is complex, so you simply can’t get cheap knock-off versions, and there are really only two brands available (Singh-Ray and Cokin).

Conclusion

Varicolors are typically only recommended for landscapes with water, and many photographers simply dismiss them as a variable tinting filter, but they can be used for so much more once you realise that the secret to their use is fixing white balance in post. After that, they become very useful, being able to make mundane color look dramatic (and often the focus of the shot).

  • They allow you to set the warmth of reflected light coming from windows in architectural and motor vehicle shots.
  • They allow you to crank up the contrast between the light coming from the sky and the light reflected from the ground, something that can make all landscape shots look different, bringing up color and enhancing lighting.
  • They create iridescence (think ‘body of a peacock’) when you shoot close-up foliage and car bodywork, especially when you have highlights.
  • They can act like an all-in-one warming-to-cooling filter when you have flat lighting

A blue-yellow varicolor is something to try out in all use cases where you would reach for your wide angle lens. It will be a firm favourite with anyone who has one of the affordable super-wide lenses (Tokina or Sigma) but you will need to do some DIY to move the filter glass from a Cokin P series cassette to a screw in filter, or you need to hold your breath and get a Singh-Ray.

Perhaps the best thing about the varicolor is that not many photographers use them. They don’t realise the white balance trick or are off put by the two stop light loss. That makes the varicolor a less used filter than it deserves and far from being an overused effect. In fact, if you pull back the effect with white balance, nobody will guess you created the effect optically!

Notes

  1. All forest photos shot with an Olympus Stylus 1 (the varicolor was hand-held in front of the lens).
  2. All seascapes shot with a Sony Alpha A77, Tokina 11-16mm, with the varicolor modded to screw onto the Tokina as a standard 77mm filter.

Capturing autumn color

When taking photos that rely on naturally colored light, you need to either manually set white balance before you take the shot, or change white balance later in post processing.

When taking photographs of autumn/fall foliage, you may find that your camera doesn’t capture the reds, browns and yellows as you saw them. This is because auto white balance is fooled by autumn sunlight, and will choose a colder (blue) white balance. The fix is to manually change the white balance.

Original image as-shot (HTC Desire HD camera phone)
Original image as-shot (HTC Desire HD camera phone)

Have a look at the image above. This is as-shot, via a cell phone (HTC Desire HD) during a walk through a wood, just before sunset, October 2012. The light was from a perfect low autumn sun, setting off the red and yellow of the leaves. Yet the photo captures none of this!

Camera auto white balance is fooled by the autumn sun and will set the white balance towards blue to compensate for the yellow cast the sun would otherwise create. The camera is not clever enough to know that you want that cast.

What to do? The solution is to either

  • Set the white balance away from ‘auto’. ‘Sunset’ or ‘Cloudy’ usually does the trick, with ‘Sunset’ being the more extreme.
  • Use an image area that you know is neutral (such as the grey hat in this case) to set white balance.
  • Simply set the white balance towards a warmer yellow until the overall image looks right.
White balance/Tint sliders as-shot (top) and after processing (bottom)
White balance/Tint sliders as-shot (top) and after processing (bottom)

For this photo, I used Lightroom’s White Balance Selector tool (keyboard shortcut, W), clicking on the hat. I also tinted the image towards magenta via the tint slider. Finally, I slightly increased exposure.

Image after white balance and tint edits
Image after white balance and tint edits

And here’s the resulting final image. The hat is now grey, but that is kind of beside the point: I now have the golden sunlight and autumn foliage as they were on the day!

More autumn Color
More autumn Color

Here’s some more photos post processed using the same white balance technique (all taken within 10 minutes of the initial photo).

Conclusion

When taking photos that rely on naturally colored light, you need to either manually set white balance before you take the shot, or change white balance later in post processing.

If you leave the camera on auto white balance, the camera tries to remove the cast caused by the colored light. Although this is desirable when you are shooting indoors (such as when you want to remove the blue/yellow cast caused by fluorescent/incandescent indoor lighting), it is rarely what you want when shooting outdoors.

Some photographers don’t realize that the issue is to do with white balance, and instead try to fix the issue using more complex color correction (HSB sliders, etc). Check the white balance first: it is a far easier setting to alter as there is only one slider.

Notes

  1. In some of the photos, I also added a small amount of clarity. If you do this, add it to foliage, clothing, hair and eyes only.  Don’t add it to the subject’s skin, as clarity has the ability to age the appearance of a person’s face.
  2. I chose to illustrate this blog post using a cell phone rather than my usual DSLR for a good reason: I have never used a cell phone camera that didn’t get auto white balance right under any outdoor condition. If you use a cell phone camera, you will typically always end up with an image that is too blue under daylight, and too yellow at night. If you use a cell phone camera often, be prepared to change white balance often if you want to capture the as-shot light ambience.
  3. The sky is blown out on some of the example photos, but this is usually unavoidable when using a cell phone: such devices have insufficient dynamic range. Available fixes for this include
  • Underexpose (although this is rarely successful as you leave insufficient dynamic range to fully capture the main subject).
  • Never make the brightest object (i.e. the sky) prominent. This is my preferred option.
  • Take separate shots of the sky and main subject, and composite them together later in post production.
  • If you have an Android/iOS phone, get a HDR app (I use HDR Camera+).

Colour Accuracy

The human eye sees an object as the same color irrespective of the angle and lighting you see it under. Your camera can’t do this because it can’t see; it blindly measures.

I talked about accurate colour and its dependency on selecting accurate camera profiles in a previous article.  I now look at the next logical step; creating my own camera profiles tailored to my camera/lens and the lighting conditions of each particular photo shoot.

The problem with camera profiles.

Using a camera profile for your camera is a step in the right direction, but as I have found since writing my previous blog on the subject, there are other issues to consider

  • Each lens has different effects on colour. My Tamron 90 macro records greater vibrancy than my Sony 18-250 super-zoom. A manufacturer’s (or Lightroom) camera profile ignores the effects of the attached lens.
  • The camera profile is created under controlled lighting conditions. You may get similar lighting in a studio, but not elsewhere.

The magic of perfect colour

Before looking at my solution, it would be instructive to show the results.

Take a look at the images below.

Mahonia Leaf
Mahonia Leaf
Red Robin leaf
Red Robin leaf
Elaeagnus leaf
Elaeagnus leaf

At the end of the photoshoot for this sequence of images, I took a photograph that would later allow me to calibrate for colour. This calibration ensures that

  • I can correct for colour inaccuracy of my camera body and the attached lens.
  • I can correct for ambient light colour.

The photos above were not tweaked for colour to make them pleasing to the eye; they were calibrated to be true to life.

On to the solution to my colour accuracy problems; I created my own camera profiles via X-Rite Color Checker Passport.

X-Rite ColorChecker Passport

All camera profiles are created with reference to a colour swatch. X-rite ColorChecker Passport (CCP) has such a swatch (albeit with a smaller range of colours than the one Adobe use). To complete the solution, CCP comes with Lightroom/Photoshop plug-ins that automatically create a camera profile from any photograph containing the swatch. Camera profile creation with CCP is easy and borders on trivial. In Lightroom you just right-click on a photo containing the CCP swatch and select Export > ColorChecker. The resulting camera profile will be saved to your Adobe profiles folder, meaning that it will now appear in Adobe Camera RAW and Lightroom.

Let’s stop to think what this allows.

Supposing I took a shot of an apple; I can create a camera profile for both my camera/lens combination and lighting conditions. I do this  by taking an additional photo that includes the CCP swatch.  This photo is used to create a bespoke camera profile. If I now apply this camera profile to my apple photograph, my apple is now colour calibrated to the CCP swatch.

Now supposing I then give you the apple, telling you to take the same shot.  Irrespective of your camera/lens or lighting conditions, once you apply your camera profile (which you create in exactly the same way I created mine), your apple will be the exact same colour as mine. The apple in your photo will be the same colour as mine, because both are calibrated to the same swatch.

It doesn’t matter if I used a Sony camera and you used a Nikon, Canon or Pentax. It doesn’t matter that I shot the photo outside on an overcast day and yours was sunny.

So what actually is the X-Rite ColorChecker Passport?

The CCP is a passport sized plastic case. Unlike the more traditional single sheet swatch, the CCP is both sturdy enough to be carried out in the field, and small enough to fit easily in a camera bag side pocket, or your own coat pocket. The CCP also comes with a lanyard (not shown), so you can even just hang it around your neck.

X-Rite Color Checker Passport
X-Rite Color Checker Passport

There are 4 plastic ‘pages’ inside the CCP. The first two pages look like this;

X-Rite Color Checker Passport: pages 1, 2.
X-Rite Color Checker Passport: pages 1, 2.

The first page (top) contains some custom white points, and clicking them allows you to change the warmth of portrait or landscape shots. Nice, but it’s the second page that contains the beef; this is the swatch that the plug-ins look for in your photos to create the all-important camera profiles.

The plug-in can always extract the swatch from the photo as long as the 5 registration points (the 4  corner brackets and the centre ‘+’) are in focus and visible. Even if they are not, all is not lost; you manually place the position of the 4 corner points. The image below shows how this works. The plug-in cannot create a profile from this photo because it is blurred and the registration points are indistinct. The swatch extraction is performed by manually dragging the four green circles, ensuring that the green squares are each on a colour brick.

Manual Swatch detection
Manual Swatch detection

Page 3 contains a grey card. This is essentially a larger version of the grey brick to the right of white on page 2.

X-Rite Color Checker; page 3.
X-Rite Color Checker; page 3.

The final page contains a quality guarantee. Worth noting is that the standards used to calibrate the colour swatches are traceable to agreed standards (via NIST; the National Institute of Standards and Technology), so in the apple example above, your apple colour will look like mine because both your CCP and mine will be calibrated to the same standards. It is worth noting that this is not the case for many other calibration systems (particularly electronic monitor calibration devices, more on this later).

X-Rite Color Checker; page 4.
X-Rite Color Checker; page 4.

Examples and discussion

Below are two photographs I took as part of the work for this blog-post.

Image 1
Image 1
Image 2
Image 2

They were taken less than 2 minutes apart under full sun using the same camera, but the wooden table and the Sony Alpha symbol (on the lens cap) in each are different colours. This is because of the change of angle in the scene. Notice how easy it is to see variance in colour between photos even when taken a few seconds apart. In this case the variance is caused by a slight camera movement!

Before discovering colour calibration with CCP, I would have thought ‘oh, it’s caused by reflected light; the change in angle in phto 2 means more light is reflected and therefore there’s more light in the scene’, and the fix is simply to reduce exposure in post processing for image 2 to give us something like image 3;

Image 3
Image 3

Image 3 goes some way to fixing the Alpha symbol’s colour, but not the wood. The wood colour is more complex (the wood is not a solid tone and has a gloss surface) and so does not match Image 1 (the browns have become more orange) and nothing will fix it. You simply can’t make a series of objects look the same colour if they were taken under different conditions unless you explicitly calibrate all your photos to a common colour reference (such as the CCP swatch).

By calibrating using CCP once for the straight down view and again for the side on view, I get consistent colour despite the change in lighting conditions. I still have to change exposure for the second photo , but this time (image 4) both the Alpha symbol and the wooden table look the same colour as in image 1;

Image 4
Image 4

Again, think about what we have achieved here. The human eye sees an object as the same colour irrespective of the angle and lighting you see it under. Your camera can’t do this because it can’t see;  it blindly measures.  We have fixed this seemingly intractable and complex philosophical problem via a simple colour calibration!

Let’s get back from the high end philosophical and down to earth with a stupid question. Does it matter that the wood is wrong in image 3? Put another way image 3 doesn’t look wrong as a standalone photo. If the photo doesn’t look odd, does it matter that the colour might be a bit out? Here’s why it can really matter;

  • If you are shooting photographs with a main and backup camera, both will give different colour. You cannot be sure which (or even whether either) is right. By calibrating for colour separately from the camera hardware and optics, you get consistent colour irrespective of which camera or lens combination you use; all photos in your shoot will be consistent.
  • Colour calibration is vitally important when compositing in Photoshop. Taking a figure or sky from one photo and trying to composite it into another is easy to do in Photoshop, but hard to do realistically because two unrelated and uncalibrated photos will have different colour casts. By using CCP, you remove all colour casts, and the only issue you have to fix is relative exposure. Exposure matching is easy (you have only one slider to match); matching colour is much harder. It involves three sliders (and more likely 3 separate tone curves if you want to do it properly), and that’s assuming the simplest case where you are in RGB colour.
  • Camera manufacturors may tweak colour to make photographs look perceptually better, or more controversially, to hide high ISO noise. This makes the camera innacurate in non-linear ways. A camera designed to give perceptually better skin tones will be innacurate for background landscape tones in the same shot. Colour calibration corrects these marketing induced kinks.

Another stupid question; should you always use CCP? No, there are some exceptions;

  • Some colour casts are useful; you may want to capture the ambient light colour via its cast. A sunset is a perfect example of this; you want to catch all that gold tinted light, and what it does to the environment! Put simply, colour correction can correct out ambience and atmosphere. There’s always got to be some thought into whether colour correction is appropriate. Even so, I now always take the CCP out with me and always take a photo of the swatch if there is time. This gives me the ability to remove colour casts if I ever need to include the photos into a Photoshop composite image during post processing.
  • Some lenses give more vibrant rendition than the actual scene. You may not want to colour correct such a lens as the vibrancy may be desirable
  • The uncalibrated scene simply looks better. The ‘incorrect’ wood colour is actually warmer than the calibrated one, and the CCP shows up better in the brighter but ‘incorrect’ photo. Depending on your reasons for shooting the photo, the warmer, brighter version might be the keeper.

Taking a calibration for every set of shots is usually overkill though, and there is a third way to use the CCP; you create a separate camera profile for each camera/lens combination. It’s not as accurate as making a profile per photo sequence, but it way more accurate than using Adobe standard, and also better than using a single Adobe/manufacturer profile for the camera body only. See note 3 at the end of this post for more information.

Workflow

Taking all the above into consideration, I now use the following workflow;

  1. I always shoot RAW, and always explicitly select a camera profile when converting RAW to TIF or JPEG. I no longer use Adobe standard because I find it particularly inaccurate for my camera make (Sony).
  2. If I have time, or colour is very important I take a shot of the CCP per photo sequence and use the generated profile in post processing. For me, colour is generally only ‘very important’ if the photos may be used later in a Photoshop composite image. Doing this allows me, for example, to composite a sky and terrain, both taken on two different days, but both calibrated to the same swatch.
  3. If I don’t have much time (e.g. I am on ‘walkabout’), I take two shots of the CCP (one facing the sun, one facing away) for my main lens of the day, and use the 2 generated profiles for all photos taken on that day’s walkabout.
  4. I have created a profile for each combination of my Sony a500 camera and 4 most used lenses. For each combination I have three profiles; inside with incandescent lighting, outside sunny, and outside cloudy.
  5. If I haven’t taken a photo of the CCP for a shoot via (2)  or (3) above, I use one of the profiles from (4).
  6. Colour is never important for certain photos. The main candidate here is a true HDR; colour is rarely conserved in HDR, so I don’t bother calibrating for it. NB – there are ways to minimise colour inaccuracy when using HDR, see this previous post.

Using the ColourChecker the way it is intended (to give calibrated colour output from your camera) is only part of the work flow. One of the coolest things about using a calibration swatch is how easy it is to either calibrate other parts of the work flow, or measure their inconsistencies.

The Camera LCD.

Most people consider three colour accuracy areas in the digital photography work flow; camera image file accuracy, monitor accuracy and printer rendition accuracy. We forget that the camera LCD plays an important role, at least for the enthusiast or non-studio based photographer. Of course, you can’t calibrate a camera LCD, but you get a very good impression of your LCD’s strengths and weaknesses simply by pointing your camera at the swatch and comparing the image on your camera screen with the actual swatch. Since using my X-Rite ColorChecker Passport in this way, I know that my Sony A500 LCD screen:

  • Brightens blues slightly
  • Desaturates skin tones a little
  • Is otherwise extremely accurate, and certainly more accurate than an uncalibrated computer monitor.

The monitor screen and printer.

There are several hardware monitor calibration devices out there, and Both Mac and Windows 7 users can use colour profile accessories provided by their operating systems. I don’t trust hardware monitor calibration because (a) certain combinations of calibration hardware and monitor just don’t work, and (b) most are not calibrated to any standard; a Spyder and Huey will give different results on the same monitor!

A colour calibrated swatch such as the CCP is better because it is calibrated to a standard. To calibrate my monitor, I set up the monitor with the manufacturers drivers (and never use the OS default plug and play monitor). That gets me pretty close to calibrated, and for final tweaks, I visually eyeball the physical CCP swatch in front of me with an image of the same thing on the monitor, and set RGB values so all the swatch bricks match. All that remains is to change the monitor colour temperature (9300k, 7500k, 6500k) depending on ambient lighting.

Finally, for the printer, I use a print bureau who calibrate their printers to a standard; I don’t think consumer level printer devices are up to it, and leave print calibration to the experts.

Conclusion

The X-Rite ColorChecker (CCP) is now my one-stop solution for colour accuracy. It allows me to;

  • be sure of colour accuracy (or on the inverse, have an idea of how inaccurate my methods will be) irrespective of my camera/computer equipment and lighting conditions
  • to remove colour casts when using multiple photos in a Photoshop composite.

A CCP is quick and easy to use. All I have to do is place the CCP in the scene at the end of each set of shots, then export the same photo to the ColourChecker plug-in to generate a bespoke camera calibration for that set of shots.

Although the CCP is not intended to calibrate them, I find it invaluable in knowing how accurate (or otherwise) a camera LCD is, and I also use it to calibrate my monitor’s colour rendition by eye.

Notes

  1. For more information and videos on the X-Rite ColorChecker, take a look at the X-Rite ColorChecker Passport Blog. The X-Rite product page is here.
  2. The leaf photos in the opening section of this post were corrected (in Lightroom) for colour via a camera profile and had sharpening and slight contrast enhancement applied. The background (a piece of white paper) was then overexposed via the adjustment brush.
  3. The X-Rite ColorChecker Passport is a 24 colour swatch of the type Adobe recommends for use in creating a general camera profile. See in particular tutorial 5 on this link.

Flash Review: Photomatix vs Nik HDR EFEX Pro vs Photoshop CS5.

Review updated and conclusions significantly revised 6Nov 2010; original review was overly critical of Nik EFEX, but the issue was almost certainly due to my own camera work!

Autumn is the time of low, cold bright suns. Those suns make a perfect subject for evaluating a number of HDRI (High Dynamic Range Imaging) applications.

Last week, I drove around the Peak district (UK) whilst taking a large number of shots directly into the autumn sun. I then reconstructed the shots as tone-mapped images using three different applications;

  • Photomatix Pro
  • Nik HDR EFEX Pro
  • Photoshop CS5

I present the results of my trial below (as well as a few other test shots) as a flash review consisting of brief pro/con bullet points. The review is aimed at existing HDRI users, and I have kept it to brief bullet points under the assumption that you know the issues in HDRI, and standard HDR photography work flow. In fact, you probably only really want to know how good the just-released Nik HDR EFEX Pro is vs existing solutions, and want some insight regarding whether it is worth changing over to it.

The images below are shot to test particular important features of HDRI, as noted in the descriptions;

high autumn sun 01
high autumn sun 01

‘High autumn sun 01’ was shot with the camera on the ground using three exposures 0.7EV apart. The sun is to the  upper right in clear air, and is actually too bright to look at. The challenge here for HDRI software is threefold;

  • To ensure that the direct sun does not white out the sky
  • To give some detail back to the road in the near ground  (as it is out of focus close to the lens).
  • To maintain realistic colour to the road and walls (which would otherwise tend towards bright blue).
high autumn sun 02
high autumn sun 02

‘High autumn sun 02’ was again shot directly at the sun, using three exposures 0.7EV apart. In this shot the big cloud has the sun directly behind it, and appeared a bright white. The camera is hand held, and there is a breeze on the barbed wire. The challenge here for the HDR software is;

  • To remove ghosting in the wire between the three shots, without losing detail in the wire, and without blurring the grass texture around the wire
  • To correctly merge the overall shots without adding motion blur, thus keeping the distant tower and treeline intact
  • To add detail to the cloud surface.

It goes without saying that without HDRI we would see blown out highlights and clipped/banded shadows for both the above images.

Although HDRI can be used to for realism (i.e. to maintain a high dynamic range), it is also often used as a creative tool (enhancing textures and adding custom styling by using nonlinear tone map compression). HDRI can thus be used creatively to add movement or texture. The following two images illustrate examples of this.

Creative HDRI 01: low noon sun
Creative HDRI 01: low noon sun

In this shot, I am pointing at the low sun and trying to control the resulting flare via a circular polariser (i.e I am rotating the flare to ensure the longest streak is oriented with the adjacent tree, and also attempting to get a long diagonal streak top left to bottom right). I am doing this to (hopefully) give the scene a sense of movement. As this scene has a very large tonal range, I exposed across the entire range of the camera (12 exposures 1EV apart).

Issues here are;

  • How easy is it to control unwanted aberrations (chromatic aberration) whilst increasing the ones we want (flare).
  • how well did the application deal with the large number of files (12 4272×2848 images).

For the final image, I am using the fact that our house is currently partway through redecoration. It has bare, stripped walls. I thought it would be nice to bring out the textures of the walls through some extreme HDRI, to give a painterly effect;

Creative HDRI 02; Self portrait with red coat
Creative HDRI 02; Self portrait with red coat

Also, click here to see a larger image of the final composition (1200×800, opens in new window)

The issues here are;

  • Ease in bringing out the textures in the image.
  • Ease of controlling the main subjects of the image (shadow and coat).
  • The composition relies on the lack of colour/texture in the shadow, and how it is offset by the big colour/texture in the coat and cushion either side of it. The intent of the composition therefore relies on the technical ability to control the colour/texture in these three areas independently of each other.
  • Ability to add detail back to areas that would otherwise be blown out (i.e. the arm of the sofa and the bright sunlit areas on the wall)

Image created with 7 exposures 1EV apart.

This image is the only one of the set that is not a HDRI test; it is the only one that I consider to be a finished image. With this in mind its probably worth spending a little more time with this image, by also showing the brightest and darkest source images;

Brightest image
Brightest image
Darkest image
Darkest image
Although I created versions of each image in each application, I have only shown one version of each image (this is after all a flash review!). Tools used per each image are as follows;
  • Image 1: Photomatix and Photoshop (Photomatix used for tone mapping only, Photoshop used for post processing only)
  • Image 2: Photoshop only (i.e. Photoshop tone mapping, and Photoshop post processing)
  • Image 3: Nik EFEX (as a plug-in for Lightroom 3). No post processing in Lightroom.
  • Image 4:Nik EFEX (as a plug-in for Lightroom 3). No post processing in Lightroom.

Photomatix Pro

Good

  • Quick user interface (once you get to grips with it).
  • Very good ghosting and Chromatic aberration reduction algorithms.
  • The HDR tool of choice for many well known HDR photographers. Practically the industry standard in HDR creation (up to now).
  • Although the manufacturer’s instructions are a little obscure, there are a few good books that concentrate almost entirely on Photomatix.  I recommend Practical HDR by David Nightingale, the best of the several books on the subject that I own.
  • Dedicated batch processing

Bad

  • Interface is initially very daunting for beginners.
  • Clearly written by programmers rather than photographers; some of the sliders are inter-related (e.g. you have to vary the gamma value after moving many of the main sliders, but this is not made obvious. This leads to a very large learning curve before you stop ‘just guessing’ and begin knowing what each control actually does.
  • No advanced features such as curves or post tone-mapping contrast control. This means that you need Photomatix and another application (typically Photoshop or Lightroom/Aperture) to complete your tone-mapped images.
  • Poor image zoom controls.

Nik HDR Efex Pro

Good

  • Shortest learning curve of all the available options.
  • Nik have clearly learned from and fixed Photomatix’s inter-related sliders. All sliders in EFEX are easy to understand and show little inter-relationship.
  • Full featured enough for advanced users, and has almost everything you need in a single UI.
  • Brilliant, well thought out UI.
  • The ‘UPoint’ Technology is a godsend for quickly spot-editing the HDR image without having to set up adjustment layers (Photoshop) or Adjustment brush areas (Lightroom). Even better, it allows you to adjust before tone-mapping so you maintain dynamic range.

Bad

  • When you save, the whole HDR image is tone mapped and re-exported as a bitmap. This means that you lose all your settings, which is not too bad as you can save your slider settings as a user preset… but you also lose your UPoints! Ouch! An option to save the HDR file and UPoints might have made sense for pro users and professional photographers (who might have to tweak a complex image tone-map for the client, etc).
  • Overuse of UPoints can sometimes introduce glow fringes (especially around trees or other complex objects) when you change the tone of the surrounding sky). This is caused by the UPoints and NOT tone mapping halos.
  • Although the plug-in controls chromatic aberration (and usually does it well) you have no direct control of it. Nik EFEX generally tends to take control of many things behind the scenes, and this may be seen as a bad point for some users.
  • Seems a little buggy when used as a plug-in for Photoshop CS5 (update; seems to crash occasionally if you do not load the exposures into PhotoShop CS5 before invoking Nik HDR EFEX… if you load the images first, it seems ok).
  • Limited batch processing (you would be typically relying on Photoshop batch processing instead).

It is worth noting that althoughNik HDR Efex Pro is a plug-in and no shortcut is added to run it as a standalone, it does seem to works as a standalone if you run the executable file in the install directory (Program files > Nik Software > HDR Efex Pro > HDR Efex Pro.exe)

Photoshop CS5

Good

  • HDR features massively improved since Previous versions of Photoshop.
  • HDR features free if you use Photoshop CS5 anyway (and if you are serious in Digital Photography, you probably own PhotoShop already).
  • Cheap if you already own a previous version of Photoshop and upgrade to CS5
  • Allows you to do (or fake) most of the things that the other solutions allow, assuming you know Photoshop well.
  • The fact that it allows you to save the 32 bit HDR file (and use non destructive editing) means that you can save (and later edit) intermediate steps in your project.
  • The default settings tend to give very acceptable realistic HDRI images.

Bad

  • Requires a very good understanding of Photoshop to use well.
  • Tone mapping options a little limited when compared to other solutions.
  • Expensive if you have to buy Photoshop CS5 (i.e. without upgrading), and certainly not worth it if you are doing it for HDRI only.
  • Although Photoshop allows you to create a 32 bit HDR file, there’s almost no editing you can do with it without first tone mapping it first. In particular, none of the filters or dodge/burn work with a 32 bit file.
  • Takes longer than either of the other two options (longer, more complex work-flow).
  • Can produce massive files (and therefore requires beefy hardware)

Results

Best use of each application;

Photoshop only: When you want to create a realistic image (i.e. when you don’t want to make it obvious that HDRI is being used).
Photomatix and Photoshop: Best tool to use when you have a difficult set of images.
Nik efex: Best general purpose HDRI tool overall. Best tool to use if you have Lightroom but not Photoshop.

For these results, I’m looking for failures that would stop the image being accepted as stock photography on technical grounds.

For the first image, all three applications did well. Surprisingly, all three applications produced good results very quickly, with Nik EFEX being by far the fastest. Photomatix required curve enhancements in Photoshop.

For the second image, PhotoShop would have failed as it could not fix the movement on the wire. I had to add the wire in manually via layers/clone tools to give acceptable results, and that took an extra 20 minutes.

For the third and fourth images, there was one outright winner: Nik EFEX. Only this application gave me the level of control (via UPoints) needed to control specific areas of the images. For example, the last image was less effective in either Photoshop or Photomatix, because I could not enhance the shadow and coat separately whilst still in the tone mapping process. Photoshop CS5 comes close, but all the close editing has to be done after the tone mapping, and you can therefore lose  tonal range (the coat came out blown out in Photoshop whatever I did).

Fora ll three applications, a multi-core processor was seen to peak at 100%, proving all three applications are multi-core aware. However with large (or many) files, hard drive speed seemed to be the real bottleneck.

Conclusion

My current HDRI work-flow uses Photomatix and Photoshop together.  I really wanted to like and move over to Nik HDR EFEX Pro, lose Photomatix, and stop having to post edit my tone maps in Photoshop/Lightroom. An almost impossible task, but Nik HDR EFEX does it.

The only downside to Nik EFEX are;

  • You don’t get quite the same level of import control as Photomatix/Photoshop (albeit this is often better for work-flow; I have only seen Nik EFEX get it wrong once in about 50 or so images!).
  • You can’t save intermediate states as you can in Photoshop. This means that once you save, you cannot easily tweak the image without running through the entire tone mapping process again.
  • Although Nik EFEX is ideal for beginners in HDRI, the instruction pdf only tells you how to use the application. Some indication on how to actually photograph for HDRI would have been appropriate. This means that if you are new to HDRI, you will definitely need a HDRI book (but of course, non of them yet cover Nik EFEX). Catch 22.

Bottom line

The work-flow improvements created by Nik HDR EFEX Pro are substantial, but you do lose a little control at the same time. Although Nik EFEX is great for about 90% of my HDRI images, I’m still finding that I need Photomatix for about 10% of them, and this is mainly where the image has large amounts of Chromatic aberration (Photomatix seems a bit better for this).

Best use of each application;

  • Photoshop only: When you want to create a realistic image (i.e. when you don’t want to make it obvious that HDRI is being used). Also useful to tone down a HDRI image by merging it with one of the original exposures (this is a common trick I use, and I need Photoshop to do this whatever the HDRI application I used). Best tool to use when you are prepared to spend a long time on your image (you can emulate most effects in Photoshop, given enough time and/or Photoshop skill). Photoshop also creates the most realistic (true to life) images, but on the flip side, it also gives least ability for creative tone mapping.
  • Photomatix and Photoshop: Best tool to use when you have a difficult set of images, e.g large amounts of chromatic aberration. Also well respected in the HDRI community, with lots of literature on best use (almost all HDRI books cover it).
  • Nik efex: Best general purpose  HDRI tool overall. Best tool for creative use of HDRI. Best tool for new entrants into HDRI, because of it’s ease of use. Best tool to use if you have Lightroom but not Photoshop.