The Color That Cannot Be Captured

The Color That Baffles Digital SLRs (Normal Exposure)
The Color That Baffles Digital SLRs (Exp -1)
The Color That Baffles Digital SLRs (Exposure -2)

I have zipped up the original RAW files and made them available for download (19MB) if anyone wants to play with these images.

Yes — feel free to play with them all you want. If you want to publish something commercial– i.e. for pay– based on this message or the incredibly valuable information contained within the comments on this post, then contact me.

List of updates: This article is getting quite a bit of traffic and some really excellent comments. I will keep updating it as information is added. I have also split the article into the original post and the updates.

  • Added link to RAW images.
  • Clarified CC license; do anything you want with it, just don’t make money off of it without contacting me.
  • Added a rainy day shot of the same flowers.

There is one particular shade of something between pink and purple that my digital rebel just cannot correctly expose. I have heard tale that this phenomana is not limited to Canon, but Nikon, too.

In any case, the top photo is what the camera thinks is the correct exposure in Program AE mode.

The color is completely blown out. Totally oversaturated. Lots of detail lost.

Even with the exposured adjusted by -1 (still in Program AE), it still blows out the color. The detail is much better, though.

Finally, with the exposure adjusted by -2, the detail of the flower becomes very clear. But that is about the only good thing about that photo.

An exposure adjustment of -1.5 is about right to capture this particular color. However, every other color is completely dark.

Odd. I’m not sure why this particular color causes such hell. Could it be because of the sensor site layout? I wonder if the Foveon X3 sensor exhibits the same weirdness?


As it turns out, this particular color — or ones very much like it — cannot seem to be reproduced in watercolor, either. My Mom was chatting with Paul Jackson a bit ago — yes, that Paul Jackson (he is an old friend of the family) — about photography and Paul mentioned that a particular flower was pretty much impossible to paint because of the color. And that color is very similar to the petunia, though a little closer to purple.

Interesting.


Laurence Matson added some comments and included some links to Foveon X3 based images.

I really really like this image; not only because it is just a great capture (and in a style I’m fond of– as some folks know), but also in that it captures a flower of a color and sharpness that I’m not even sure my camera is capable of! I’ll have to track down a similarly colored single bloom and see what I can pull off.

Thank you!


Rainy Petunias

Conveniently, it is an overcast and somewhat rainy day today. Thus, the lighting on the petunias is now thoroughly ambient and considerably less intense than the day when the original photos were taken.

This is a cropped but otherwise un-touched shot of the flower in the resulting light.

It looks tons better than the original but stil a bit odd and certainly not at all like real life (wherein the flowers are quite a bit more pastel).



14 Responses to “The Color That Cannot Be Captured”

  1. Pete says:

    What seems to be happening here is that the particular tone is senses as darker than normal by the meter. There could be any number of reasons for this. In any case, when the meter in the camera sees a dark thing it tries to overexpose to make it lighter (more on why here). The color algorithm in the image processor might also be contributing here.

    Note though that the light meter in the camera does not use the imaging sensor to pick expsoure. Still, I’d say the meter *and* the imaging engine are conspiring to get this wrong.

  2. David Evenson says:

    I wonder if this has anything to do with it.

    http://www.null-hypothesis.co.uk/science/strange-but-true/profs-probings/colour_spectrum_magenta_complimentary_bizarre

  3. Laurence Matson says:

    These are colors which are getting close to or at the edge of the gamut.

    It may be possible to capture that color with your digital camera were you to shoot in raw. Raw allows you to retrieve more information from the captured data than a fully processed jpeg does. The jpeg has already been compromised beyond rescue.

    The Foveon X3 imager does a pretty good job capturing images at or near edge of the color space. Here are a couple of examples taken with the Sigma SD14:

    http://www.pbase.com/lmatson/image/75707240
    http://www.pbase.com/lmatson/image/85185554

    or the SD10:

    http://www.pbase.com/lmatson/image/45073468

    The final example shows where the limit is approaching. The imager was not able to capture all of the gentian color lit by full sunlight.

    There are other examples in the full galleries.

    Laurence

  4. Laurence Matson says:

    A small additional note:

    The image of Friederich’s Garden (http://www.pbase.com/lmatson/image/75707240) cannot be rendered in print very well. When doing so from an RGB file (Adobe RGB), the colors of the non-yellow flowers are clipped terribly. It is necessary to take the image into Photoshop for CYMK remappping before putting it back into Adobe RGB for printing. Obviously, this compromises the color greatly – in the print they go in the right “direction” but are much less vibrant. There may be printers with a much greater gamut than my Epson 9800, but I assume that their color space will still be less than the digital rendering for a monitor.

  5. Gary Martin says:

    I can confirm this effect with a Nikon (D40X). The flower has a really vivid deep red/purple – perhaps an almost luminescent burgundy – and the saturation when it’s in direct sunlight it quite startling. Tried a number of times to capture the image, but I just couldn’t get it right. Will have to wait until next year to try again.

  6. Jacob Rus says:

    It’s also quite possible that the color is within the gamut of your camera, but outside the gamut you are saving to in JPEG. Try to see what the detail is like if you convert the RAW image to ProPhoto RGB (by the numbers; if you look at it on screen it’ll convert to your screen gamut and still be blown out), a wider RGB gamut specifically for this sort of thing.

  7. Jacob Rus says:

    Actually, looking at that picture in Camino, which does not know how to do any kind of color management, I’d say that the detail in the top image is okay. It looks like it’s mostly getting blown out when converted from Adobe RGB to your monitor’s color space. So with a wider-gamut display you might be fine here.

  8. n[ate]vw says:

    Edge of the gamut? Rats, I was hoping it was evidence for tetrachromacy!

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  10. eric soroos says:

    It’s out of gamut, and possibly out of the colors that are representable by an RGB color space.

    You’re asking for Bright, Saturated Red (magenta really), and once you get enough saturation, you don’t have enough brightness. You simply can’t get saturation and brightness in an rgb space since as you get to full brightness, you go to white.

    The solution is the LAB color space, which can do things with non-representable colors and then keep the rendering intent as the color is mapped onto a display space. That colorspace uses Lightness and two color axes, blue/yellow and magenta/green, so you can specify an intensly bright, intensely magenta color. See the book “The LAB Colorspace” by Dan Marguiles for as much detail as you could possibly want.

  11. Jacob Rus says:

    It turns out that most of the data is indeed within the Adobe RGB gamut this image is saved in. Here’s what I was able to do[1] tweaking the L*a*b* curves in Photoshop (actually mostly the a* curve, with a bit of correction of b* to maintain hue.

    I brought it down so that things mostly fit in the gamut of my 12″ powerbook, which is very limited, so you should be able to see detail (i.e. varied chroma+lightness) fairly well on a wider-gamut display. Shows, as Eric says, the power of the curves tool in “Lab” color mode. And I’ll second the recommendation for Margulis’s book. Even though some of the explanations are a bit suspect (dare I say wrong?), for the most part, it has good practical advice (at least the chapters I skimmed in a bookstore one day :).

    [1]: http://www.hcs.harvard.edu/~jrus/bbum-edit/magenta-flower-edit.jpg

    The image is licensed as CC-BY-NC-ND, so this is technically outside the license and I’ll be happy to take the edited image down right away if you like.

    Edit: apparently your spam filter doesn’t like links. :/

  12. Chris Hanson says:

    I believe your need a CCD that can register squant as well as the SquantViewâ„¢ plug-in to properly handle that color.

  13. Jeff Sickel says:

    I’ve got a Sigma SD14 and noticed an odd thing in the same vein when I shot petunias on a bright day as a drive by (literally, from the passenger side of a car w/o much time to set up the shot). At first the flowers looked like they just jumped out more than it should have–until I walked passed another set of petunias on a bright sunny day and realized that the image captured much of the tone that I usually missed on other digital cameras. Granted the image isn’t that great, but I could post it as a comparison if people want.

    I tend to only shoot RAW with the SD14. Even so, I’ve found that when converting to TIFF/JPEG I need to be careful about the output profiles. Many tools (Aperture and Light Room included) can too easily let you dump out a profile that just washes out the image–aka, watch out for that default setting to sRGB.

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