Having trouble with my sky blueness . . . .

I mainly photo birds, but only as an amateur. This means squeezing the best image from a poor shot of a tiny bird in the distance.

Shooting RAW and developing with darktable has given me great results over the last 7 or 8 years, however, I often noticed that the sky in the background was not a realistic blue. I put this down to the exposures being correct for the bird, not the sky.

Anyway, on a recent trip to Egypt I was snapping scenery, pyramids, temples - lots of beautiful, clear blue sky in the background. I was using a Canon R6 with an EFS 17-55mm lens. Mostly I used the Canon auto setting, but taking RAW images (note they always look super good in the R6 viewfinder, especially in darkened tombs!).

The embedded JPGs look pretty decent, but as always, darktable can pull out more detail and give more crispness and pop to the image. The first problem is to read the Canon RAW format .CR3 - I use the Adobe DNG Converter to convert to DNG format, which darktable can read.

I am now using darktable 3.4 so the Color Calibration module is available, but here is my problem. Setting WB to Camera Reference, CAT to CAT16, the sky often comes out a darkish blue no matter which illuminant I choose. Again it could just be the sky is underexposed but then how do I correct this? In the attached image it is tricky to create a mask for the sky and not get haloing around the statue. If you try to boost the blue in the calibration blue tab, then other parts of the image get overexposed. I guess a mask+ parametric approach could work, but thats a lot of work for several hundred images.

ER6_4832.dng (9.0 MB)
licensed as Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)

One last point: in the Color Calibration section of the manual it says that “DNG RAW files are also ignored” does this mean the WB and input settings are ignored, and the DT defaults are the problem? If so, what options do I have for my converted DNG files as there is no assistance available from Canon.

Apologies in advance my lack of understanding means i phrased the question badly.


The attached is the best I can do without masks.ER6_4832

You definitely have a bit of a magenta thing going on there…

I took your dng and developed it in rawproc, which doesn’t hide any operations. I used the libraw-provided camera primaries for the Canon R6, the as-shot white balance multipliers, and a rather tame filmic curve for the tone lifting, and I get a nicely-colored blue sky. I’m posting my rendition at risk, you need to ascribe a license to the .dng that allows others to post renditions with attribution, e.g., https://creativecommons.org/licenses/by-sa/4.0/

Edit: Ignore the black borders, that’s an apparent bug in how I’m handling the raw vs visible image dimensions provided from the .dng by libraw… Geesh.

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I guess the real issue whether the colours match up to my memory of the scene. In your image, I think the sky is darker than real life, and the stone work is paler - all the stone in Karnak is honey coloured or pinkish.

In my image I got the right colour on the stonework, but no the sky.

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play with the colorfulness and brightness tabs in the color calibration…even a small adjustment to brightness in the blue will nicely darken your sky or lighten it as needed and then tweak the color…you might find a nice look without too much work…

Sky still a bit dark, although you are right about the magenta.

Trouble is, boosting the blue loses some detail on the statue

That’s a rather hairy topic. Our recall is first based on our interpretation of the scene at the time, light pushed through our eyeballs onto a neural morass. Assuming that’s consistent with the CIE 1931 observers (this is to what most of our color science is anchored), we then put time between the observation and our recall that can also futz our assertions.

What I do to combat all that is to start with a neutral processing, using the measured camera profile and the camera’s notion of white balance. What I find is that the camera has better memory than I of color, so I start with that as a point of departure for manipulations. I’ve gone back and re-processed some of my raws that I did without that perspective, and I’ve been amazed at how wrong I was back then.

Food for thought…

Edit: Oh, I live at a high altitude, and have come to accept such dark blue skies as de riguer. It’s not as unnatural as you might think…

Good points.

In fact I have been questioning my memory for lots of the photos inside tombs, where there was a low level of fluorescent (I think).

Depending on the CAT settings, the colours come out very different, but still realistic for the lighting conditions. Its hard to match up to my memory, and even worse when I looked at the honey coloured stonework, I couldnt help thinking that the tomb illumination was giving it too much red.

I guess in the end I have to make some choices to get the best image.

Re the northern darkness : the sky is definitely brighter in Africa, certainly brighter than the grey skies of London.

Standard modern workflow with filmic, +1.7 EV and some contrast tweaking. Looks ok for me:

ER6_4832.dng.xmp (9.6 KB)

Yes that looks fine, but I can’t get away from the feeling that the blue sky was brighter than that.

As ggbutcher says, its probably in my imagination.

I often use color zones to darken the sky :wink:. The opposit is possible, too. There you go:


ER6_4832.dng.xmp (10.4 KB)

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ER6_4832.dng.xmp (8.6 KB)

Since you are a bird photog, why not white balance on the bird’s mask?
Then I concentrated on getting more structure in the statue.
In case you do not like the sky: experiment with all useful settings
in the color balance module, for instance.

Have fun!
Claes in Lund, Sweden

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ER6_4832.dng.xmp (11.2 KB)


exposure, tone curve, vibrance, local contrast, texture boost


I followed your tips on what the scene was like and came to this.
Basic modern, scene referred workflow plus another masked color calibration instance to get what I think is a more natural sky (I used the white sign in the background as the neutral reference). And warmed a bit the default color calibration instance to get more punch in the stone.


ER6_4832.dng.xmp (13.1 KB) (dt 3.4)

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Ok some great comments and contributions, but let me get to the heart of the problem.

I took 1000 pictures in 7 days, and what I would like is a couple of baseline styles (scene referred modules) that would fit most of the pictures, leaving me to tweak the photos that deserved more attention.

The image I posted is really all about the statue - the detailing and colour of the stone. The sky is a pretty background, and the girl posing in the foreground gives some human scale. What I want to do is make some choices in filmic, color calibration, exposure, and local contrast, then save these as a style that suits a couple of hundred photos.

Looking at the contributions above, Claes hits the detail on the statue, and gadolf hits the right sky blueness. Is there a combination that I could save as a style, preferably only using scene referred modules, that would be a good baseline for all similar photos. Maybe that is an impossible ask, and if so I am happy to use all the tips and hints above!

First of all, nice photo. :slight_smile:

One way to brighten the sky is to add saturation. Low saturation colours tend to appear darker perceptively. As for the magenta, if I recall correctly, Canon tends to be more reddish to favour skin and warm tones. Not sure if their raw files are biased in that way.

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How about this one in terms of color and tone? Sorry for the lack of detail.

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I’m surprised by the quality considering this is a crop lens on a 20mp full frame body :open_mouth:

Why not, out of the box with a dcp profile and a slightly hue adjustments in cie lab
ER6_4832.dng.pp3 (14.8 KB) ER6_4832

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