Sulphur-crested cockatoos

And for a break from solar cars, here are some sulphur-crested cockatoos enjoying the Australian winter sun:


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Pencil charts for visualising colours

As a result of a discussion with a photographer friend of mine, I’ve been thinking (not for the first time) about visualising the colour palette of images. Consider this sunset, for example (a picture I took in Adelaide 8 years ago):

The photograph is rich in yellow and orange. However, the apparent blue in the sky is actually grey, and the apparent grey of the sea is actually brown. If we postulate a standard set of 35 plausible pencil colours, and map each pixel to the closest-matching pencil colour, we get this (I have done the comparison in RGB space):

Then we can visualise the colour palette of the image by showing the wear on the virtual pencils, if each virtual pencil has been used to colour the corresponding pixels. It can be seen that a lot of orange, brown, and grey was used (click to zoom):

Conversely, this beach scene (photographed in Vanuatu in 2016) is rich in blues:

The warm light greys of the beach don’t quite find an exact match among the pencils, but the other colours match fairly well:

And here is the pencil visualisation (click to zoom):

If, rather than using a standard set of colours, we extract the pencil colours from the image itself (image quantisation), fewer pencils will, of course, be required:

The fit to the original image will be much closer as well:

So this is a trick to remember for another day – pencil visualisations!


Molecules: a book review


Molecules by Theodore Gray

I recently purchased Molecules: The Elements and the Architecture of Everything by Theodore Gray of periodictable.com (this is the sequel to his superb The Elements, which I have previously reviewed). The book is packed with interesting facts about chemistry as it relates to daily life, and the photographs are absolutely beautiful, as this two-page spread shows:

The structure of the book is necessarily a little ad-hoc, lacking the obvious pattern of The Elements. However, it is still well-organised, informative, and compelling. Everyone interested in science should probably have this one on the coffee table too.

I would give this book five stars, except that nothing could be quite as good as The Elements. I should also note that Theodore Gray’s Reactions is coming out soon. I expect that to be worthwhile as well.

* * * *
Molecules by Theodore Gray: 4 stars


More African animals

Here are some more pictures of my recent trip to South Africa (click to zoom):


Giraffe (photo: Anthony Dekker)


Impala (photo: Anthony Dekker)


Pin-tailed whydah (photo: Anthony Dekker)


Wildebeest – also known as gnu (photo: Anthony Dekker)


Little egret (photo: Anthony Dekker)


Warthog with babies (photo: Anthony Dekker)


African animals

Here are some pictures of my recent trip to South Africa (click to zoom):


Burchell’s zebra (photo: Anthony Dekker)


Lion (photo: Anthony Dekker)


White rhinoceros (photo: Anthony Dekker)


Southern masked weaver (photo: Anthony Dekker)


African elephant (photo: Anthony Dekker)


Goliath heron – world’s largest heron (photo: Anthony Dekker)