I chose today's image for its illustration of how cameras capture colours, and why it isn't always useful to rely on photographs if one wants to know the "true" colour of an object. It's a contemporaneous subject, as there seems to have been much debate about a dress the past couple days: "The Science of Why No One Agrees on the Color of This Dress" (via Wired).Most botanists I've met wouldn't know an Internet meme if it smacked them upside the head :)
In today's photograph, those parts of the unfurling flower in shadow have a bluish-cast, including not only the tepals but also the fuzzy hairs on the distant perules (or bud scales). Those parts exposed directly to the rays of the sun have a daytime "white" light to them, which is most noticeable on the forefront line of those fuzzy hairs, though some tepals have a bit of daytime light on them as well. To make matters more confusing, some of the tepals are side-lit so that they are glowing with the light that has diffused through the tepal. For another photograph of a flower from this particular plant, this time in late-evening golden light, see this previous entry on 'Eric Savill' magnolia. Different lighting conditions, different colours.
For scientific photographs and scans, colour calibration charts or cards are often inserted into the images to permit later correction to standard colours under standard conditions. For example, see this specimen of Corydalis aurea from the UBC Herbarium, but do note that while the colour calibration chart is present, the image is not yet calibrated--e.g., the black in the chart is not a true black.
Saturday, February 28, 2015
BPOD, of course. The text of today's entry contains this, which surprised me: