Cleaning the Background

Usually I don’t like wildlife images with a subject on an absolutely “creamy” background unless this effect was obtained in a natural way — with a lens and not through postprocessing. When the background isn’t detracting from the subject, I rather prefer that the objects in it, such as vegetation, soil, or rocks, are blurred but still a little recognisable than when it is looking just like a homogenous colour backdrop. In certain cases, however, I agree that the background has to be tweaked after the shot. More often it is necessary in the images of small subjects created with use of a macro lens. Since narrow aperture and consequently greater depth-of-field are typically required in macro photography, the not very distant objects in the background may appear in the image not blurred enough. Such photographs are then criticised as having a disturbing, “busy”, background — when the separation of the main subject isn’t sufficiently provided.

Macro photographers often use artificial backdrops — prints or colour paper — that they put behind the subject before making the shot. Obviously, this is possible only with static or slow-moving and not shy subjects, such as flowers or caterpillars. In most other situations the background can’t be controlled that well, and the photographer is confronted with a dilemma — to leave it as is, or to improve it in a graphic editing software. Sometimes the background looks so “dirty” that there is no other choice than to work on it in Photoshop. In my photography practice this need usually arises when I have photographed and underwater subject with a macro lens.

I use a small water tank that I built extra for this purpose from acrylic glass. Since I currently have only one such tank, it is quite wide, so that I can put also larger fishes and amphibians in it. For small animals, there is too much space, and this causes two problems. First, it is difficult to compose an image because the animal has too much freedom to move along the front glass and quickly leaves the view field of the lens. Second, the subject tends to swim away from the front glass thus leaving the area in focus. To solve these problems, I use dividers which are also made of acrylic glass. One of them limits the distance from the front glass and is made non-reflective — to absorb flash bursts.

When I photograph water animals in this tank, I fill it with clear water. Nonetheless, swimming dust and dirt particles can’t be avoided completely: Even when the water was absolutely clean they emerge as soon as the animal and the decoration objects are there. These particles appear in the photographs due to magnification by the macro lens. Air bulbs are a much worse problem: When the water was fresh and cold, they remain there for hours and appear in the photographs. When they are out of focus, it is even worse because they look like snow flakes. All this you can see in the picture below.

Of course, as in so many images captured with macro lenses, the background in this one looks very homogenous, and the foreground appears as if sticked on it. However, there is nothing wrong because the same effect can be observed in macro photographs that didn’t undergo the post-processing described in this article, i.e. that remained as shot.  Also, with this photograph of the newt, if we compare the original with the result, we would recognise that in the original the foreground was also looking “sticked”. The only difference was that the background was extremely messy. In the process described in this article I solved this issue, and, as you see below, the result was worth the efforts.

 

Read the complete article Cleaning the Background.

Black Image Export Bug in Capture One 7.1

Since the update of Capture One 7 to 7.1. a couple of months ago, another quite annoying bug emerged in this software: When a file with an image is exported as TIFF for additional processing and Photoshop opens it, what you see is only a completely black surface.

Since version 10.6. (Snow Leopard) Mac OS X includes Open Computing Language (OpenCL) – a programming framework that facilitates access of applications to graphic processing hardware. In the developers of Capture One made use of it. This had to be one of improvements of the version 7 compared to Capture One 6. The use of hardware acceleration via OpenCL is supposed to improve the processing speed of images on Macintosh platform. Unfortunately, this seemed not to work in my combination of Capture One 7.1 and Mac OS 10.8. Some other CO users also reported this problem.

I hadn’t updated my installation to 7.1.1 yet, so I don’t know if this bug was fixed. Since I don’t see it mentioned in bug fixes list, I assume that it wasn’t yet. In my current Capture One 7.1 installation I use the workaround showed in the following screenshot:

Turn off hardware acceleration for processing.

Turn off hardware acceleration for processing.

Open the Preferences of Capture One. On the first page General, select Never in the drop-down list for Processing in Hardware Acceleration (Use OpenCL for). This means that hardware acceleration wouldn’t be provided after that anymore. However, I don’t notice any improvement in the progress of file export when it is turned on.

Capture One vs. Adobe Photoshop Lightroom: White Balance

This is an excerpt of a larger article. The complete text is available here: http://www.nature-images.eu/contents/articles/c1-vs-lightroom-wb/index.html

White Balance Set To Daylight

Since the colour temperature of daylight varies very much, it seems logical that Adobe Photoshop Lightroom (or more precisely Adobe Camera Raw that underlies it) and Capture One may have different default Kelvin settings in daylight mode than Canon. This happens indeed: While the “Daylight” preset in Lightroom has the colour temperature of 5500K, i.e. that of normal daylight, and tint set to +10, in Capture One, these are 5305K and +2.6.

The higher the Kelvin value, the “warmer” is the colour, i.e. the greater is the shift of it towards red, yellow, or magenta. Lower values result in dominance of “colder” tones — blue, green, or cyan. Since the temperature value in Capture One is lower, the image tones should be colder than in Lightroom, and they are indeed — as the images shown below demonstrate.

Compare the image in Capture One Pro 7 and Adobe Photoshop Lightroom 4 after the white balance was set to “Daylight” (Click on pictures to enlarge):
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Capture One Pro 7 — 5305K / +2.6
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Lightroom 4 — 5500K / +10.

In the same image, the colour in Lightroom looks warmer than in Capture One. This is what actually has to be expected.

It becomes strange when the Kelvin and tint values in Capture One were set to the same as in Lightroom. Of course, the same colour temperature values should result in the same white balance, but in Capture One Pro and Lightroom they don’t. If you look at comparison below, you would notice that the left image — the one that was produced in Capture One Pro 7 — has pretty strong magenta colour cast.

Compare the same image when the colour temperature and tint in Capture One Pro 7 are set to the same value as in “Daylight” preset of Adobe Photoshop Lightroom 4 (Click on pictures to enlarge):
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Capture One Pro 7 — 5500K / +10
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Lightroom 4 — 5500K / +10.

One could think now that the white balance adjustment in Capture One is faulty, but this issue is not that simple. After I pushed the tilt slider to around +3, i.e. reduced magenta by 7 stops, the colour cast disappeared, and both images were looking similar. Hence, “daylight” has the same meaning in both programmes but the tilt slider has a different scale: For roughly the same colour appearance, the tilt value in Lightroom has to be triple as high as in Capture One. In Lightroom the tilt slider goes to 150 in both directions while in Capture One it is limited to -/+ 50 but allows decimal values. Therefore +3.3 in Capture One is close to +10 in Lightroom.

Having the colour temperature of 5200K the images that a Canon camera creates should have a bit colder colour than the standard daylight and even than the daylight preset in Capture One. Tint is another adjustable parameter that influences the look of an image. However, it is absent in cameras though available in raw converters and image editing software where it allows fine tuning of white balance through adjustment of the tones in a range between green and magenta.

Compare the image in Capture One Pro 7 and Adobe Photoshop Lightroom 4 after the colour temperature was set to the same value of 5200K as in daylight WB preset of a Canon camera (Click on pictures to enlarge):
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Capture One Pro 7 — 5200K / 0
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Lightroom 4 — 5200K / 0

The colour temperature scale is universal and absolute, hence the same colour temperature always has the same Kelvin value. Obviously, zero is zero — in other words, zero is nothing. Therefore, if tint was set to “0”, it should result in a balance between magenta and green, i.e. no bias towards either should be noticeable. As you see in the above example, it isn’t the case: The image in Lightroom has a stronger presence of magenta while the one in Capture One looks a little greenish.

Since the experiment with the daylight setting that I described above has proved the correctness of Kelvin scale in both programmes, I assume that here again it is the tilt setting that causes the problem: Either in Lightroom or in Capture One, or in both, zero tilt in fact isn’t zero. To me the image in Capture One looks not only more natural but also close to what I was photographing: The shield on it was hanging in bushes — not in the sun; therefore the light was for sure not as warm as in the image rendered by Lightroom.

White Balance “As Shot”

The difference in white balance treatment in both programmes is even more evident when an image has just been converted from a raw file and no adjustments were made. Both, Capture One and Photoshop Lightroom always set own white balance values upon import of an image and ignore the camera white balance. The picture below shows the same image shot with 5200K and 0 tilt as it appears in Capture One and Lightroom upon import.

Both, Capture One and Lightroom ignore camera white balance and set their own temperature and tint for imported images. (Click on pictures to enlarge):
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Capture One Pro 7 — 5305K / +2.6
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Lightroom 4 — 4850K / +1

For some reason that probably only developers of Lightroom know it sets the colour temperature to 4850K and tint to +1 in images that originally have 5200K and 0 tint and calls this white balance “As Shot”. Surprisingly, the white in the image appears more neutral here compared to its look in the above example — when I set the colour temperature to 5200K. The overall contrast, saturation and colour balance in an image imported to Lightroom are also more neutral than in Capture One.

Although the white balance looks okay, the image in Capture One appears to have a little more contrast, and its colour is more vivid. In Capture One, the import WB parameters for images shot with daylight preset are closer to the original and identical to the daylight preset in this programme: 5305K and +2.6.

Unlike Lightroom where the import white balance is “As Shot”, in Capture One Pro 7 it is called “Custom”. However, if you select there “Shot” from the drop-down list, the values will remain the same — as you see in the following sample pictures:

In Adobe Photoshop Lightroom the white balance set at import is called “As Shot”. In Capture One it is initially labeled as “Custom”, however, the values remain the same when you select “Shot” from the list (Click on pictures to enlarge):
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Capture One Pro 7 — 5305K / +2.6
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Lightroom 4 — 4850K / +1

Corrected White Balance

The discrepancy in Kelvin and tilt values between two programmes becomes even greater after the white balance was corrected. If in-software automatic WB correction was applied in Adobe Photoshop Lightroom, the colour temperature of the image is displayed as 4500K with +2 tint. In Capture One these values are much higher: 5031K and +4.6 tint. However, both programmes decreased the colour temperature of my test image by the same value of about 300K — from 5305K to 5031K and from 4850K to 4500K. (See pictures below.)

Automatically set white balance by software algorithm: The result looks in Capture One and Adobe Photoshop Lightroom similar but the values defer very much (Click on pictures to enlarge).
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Capture One Pro 7 — 5031K / +4.6
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Lightroom 4 — 4500K / +2

Visually, the result of correction in both programmes is satisfying though I like the image in Capture One more. The colour tones of the image created in Capture One are closer to the original while he image in Lightroom looks colder.

The most reliable and the easiest way to correct white balance is by using a neutral grey reference object. In landscape photography it can be a stone, but better results are achieved with a standard grey object — a grey card or cube. For testing the white balance the reference should, of course, have standard grey colour. In my tests I used a small grey card DGK-M Mini made by Digital Image Flow. In the test image used in this article you see it hanging on a twig near the warning shield.

Below you see the test image after correction via a grey card in Capture One Pro 7 and Adobe Photoshop Lightroom 4. The colour temperature and tint set according to grey card are higher in both programmes than the values set by built-in automatic adjustment.

Compare colour temperature and tint after white balance was automatically corrected with values taken from a grey card (Click on pictures to enlarge):
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Capture One Pro 7 — 5330K / +2.1
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Lightroom 4 — 4900K / -2

For my eyes, the result in Capture One looks better again: The white of the shield is clearer. In Lightroom it has a slight greenish colour cast that is barely noticeable but the diagramme in the top left corner helps to determine it.

Conclusion

The fact that the colour of an image in Capture One shifts only slightly when WB presets are changed or when white balance is automatically adjusted from grey card lets me assume that this programme does it correctly. Also the appearance of the image in Capture One was quite close to that one that I was seeing through the viewfinder of my camera. In comparison to this, obviously, something is wrong with colour processing in ACR or in Lightroom. It may be a matter of taste, if the picture has more contrast and is more vivid, as it is in Capture One, or with less contrast and desaturated, as in Lightroom, but the colour temperature and tint values in these two programmes do not match at all, and the white balance in Lightroom doesn’t even come close to the setting of the camera. The reason is for me a mystery. To me it looks like a flaw that undermines the reliability of Lightroom as of an image processing tool. This is very disappointing since this software is so great in many other aspects. I have a strong hope that Adobe would improve it some day. Till then I, personally, would prefer to use Capture One for colour adjustments in raw files.

Something ingenious doesn’t need to be complicated

Something ingenious doesn't need to be complicated

Here is a solution for the well-known problem with laptop screens that can drive mad everyone who requires confidence in colour presentation – for instance, a photographer processing images on a mobile computer.

I don’t like the realization though: A piece of velcro has to be sticked to the laptop housing from outside (ugly and inconvenient – particularly on small laptops), this little gauge thing can be lost very easy… I’d wished the laptops to have such a viewing angle indicator built in.