Dual illuminant DNG profiles
Dual Illuminant DNG camera profiles
When lighting varies
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Keith looks at quickly creating DNG dual illuminant camera profiles for testing lenses, cameras, and lighting under variable lighting conditions. Using a few photos of an X-Rite colorchecker card and their free camera calibration software is all it takes.
DNG profiles are a great way of optimising photos taken under unusual lighting conditions, but a dual illuminant profile can give a bit more flexibility when conditions vary.
Oh, and it’s also useful if you use old software that doesn’t fully support your latest camera…
Custom lighting and variable lighting
When I’m working in a studio I have full control over my lighting and can create custom DNG profiles to aid in the processing of my RAW camera files. I happen to use these with Adobe Camera Raw (ACR) and Photoshop most of the time, although I do occasionally use other RAW file converters.
I’ve found custom DNG profiles, of the single illuminant type very useful for specific lighting setups, such as LED and compact fluorescent (CFL) lighting. I’ve many examples of creating and using the profiles in my lighting related reviews.
A single illuminant profile was all that was required for this conference venue. There are some similar examples covering product photography lighting in my recent look at the ColorChecker Nano card.
In real life I often shoot in conditions of variable lighting, such as working factories. Here it can help to make use of the Dual Illuminant option in X-Rite’s ColorChecker Camera Calibration Software – [free Download ]. Profiles help with consistent reproduction of colours – especially important when a client has equipment/products painted in distinctive colours or has a coloured logo.
Source images for profiles
At its simplest, take two well exposed photos of a colour checker card, one with the warmest lighting around and one with the coolest.
How to tell? If you shoot in RAW format, your image processing software will usually have an ‘as shot’ option for colour temperature. This can be fooled (see below), but white balancing on one of the mid grey patches in the white->black strip will give you an idea of the colour temperature of the light source illuminating the card.
You don’t need the profile at the time of shooting, just a set of photos of cards under the different lighting present. Then you can create a profile (or profiles) and see how it improves colours. This is most often noticeable if there are artificial sources of light around newer than good old fashioned tungsten light bulbs.
Another use – new camera, old software
For various reasons I still use Photoshop CS6 – most importantly it supports processing the RAW files of the Canon 5Ds I use for my work. At some point I’ll move on – probably when Canon bring out a mirrorless successor to the the 5Ds. It has camera profiles for the 5Ds but doesn’t support my Canon EOS RP [review]. This is a backup and ‘experimenting’ camera. For processing the RAW files I use the free Adobe DNG converter to produce DNG versions which I can then work on. Now, if I really needed processing of the RP .cr3 RAW files I can always use DxO PhotoLab or other newer packages.
Years of past work in IT has left me with a strong feeling of: ‘upgrade to experiment, but keep your production machines stable until update is absolutely necessary’
So, yes this is of relevance to me, and many others I know who still use ‘old’ but perfectly good software ;-)
A quick DI DNG profile
I was out testing an old lens [Soligor 300/5.6 – article] on the RP and wanted to look at the colours compared to another Canon lens. Now you can do this by just shooting the card under the same lighting with each lens, but I was in ‘experimenting mode’ ;-)
So, I shot two photos (exposed for the card) of the ColorChecker Passport. One in direct sunlight (warm) and one with the card pointing to the northern sky (cool)
Here are the files in Adobe bridge (no I don’t ever use Lightroom – that’s an entirely different story)
Here’s the ‘cool’ shot – the camera is giving an ‘as shot’ colour temperature of 4550K.
This warm value is coming from the warm colour paving slabs and those yellow road markings. These are also over exposed, but remember, it’s the card that we need correctly exposing. If you’re unsure, bracket exposures and check that no parts of the card image are clipping.
Here’s the card in full sun. The temperature shows as 4900K
The DNG files have no adjustments for use with the camera calibration software.
I’ve selected ‘Dual Illuminant DNG’ and just drop the two DNG files onto the window.
The software will normally autodetect the targets.
The cool shot target is detected too.
Then it’s a simple click of the button to create your custom profile.
I have others for the RP but this one will do as a general ‘outdoors’ profile.
Now when opening my RP RAW files in ACR, I have this default profile available.
Here’s the cool shot, white balanced for the card, with the new profile being used.
Using the profile
The profile creation photos were taken using a Canon EF50mm F1.4 lens.
I tried shots with different lenses to see how they differed. Not a lot. However, to be honest, if I can’t obviously see a difference from using a particular lens, it’s not something I’ve been bothered about in the past.
Since I shoot all my work in RAW, and it all gets processed to some extent, that idea of lenses having a special colour rendition has not really been something I’ve seen as any relevance to my work (yes, it mattered more with film).
The RP + EF lens profile just gives me a slightly more consistent baseline when testing stuff on the RP.
This new profile gives a good rendition of outdoor colours for the RP. In this instance, actually paying for some new software would likely achieve the same results though…
Where the profiles are of significant use is when your lighting isn’t consistent.
This is a variable colour LED light – using the warmer setting causes much less mismatch with ambient room lighting (which is often warm).
Matching it to ambient lighting can be useful, but you still want accurate colour.
I’ve a lot more about this in the ESDDI 14″ LED ring light review
Meanwhile. back to the lens I was testing [click to enlarge].
The profile slightly changed the colour cast of the sky, but if you’ve ever edited many skies with clouds, you’ll know just how much colour lurks in most ‘white’ clouds.
You can also get the free DNG Profile Manager software which you can use to activate/hide profiles and rename them. If you make profiles often then do pick informative names. I have quite a collection of profiles created over the years. I keep them just in case I need to go back and process a client’s files, but I’ve no desire to clutter up my profile menu (in ACR) with dozens of profile made for lighting in assorted factory buildings around the UK.
The ColorChecker software is available from X-Rite
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