The Images I Have Used

The images I have used in creating some of my programmatical images have been used courtesy of those who have licensed their images through Creative Commons.  For those images where attribution is required, there is a tab below linking to the original.  The images I have created are copyright, other than those which are specified below as being “share-alike”, where they are available under the same licence as the original.  To see the images I’ve created, you can look at Instagram, or Facebook.

My thoughts on HDR

When it first gained popularity a few years ago, image sharing sites like Flickr were awash with heavily processed, ultra-high contrast images with halos around trees and clouds.  They were fascinating pictures, because they were some of the first easily created photos that allowed you to see the detail of both dark and light areas of the image.  The novelty of these images quickly wore off, but the software that processes them has been refined and, although I’ll still go for a slightly over-processed look sometimes, I use HDR to try to recreate what I saw when I was there.  As much as technology has moved on, the human eye is still slightly ahead, and the brain makes a pretty good job of adapting quickly to give you an overall view that captures as much detail as possible.

Bracketed exposures of Canterbury Cathedral

Bracketed exposures of Canterbury Cathedral

Even phones will now take HDR photos for you, automating the processing to give an overall result of detail in areas that would ‘struggle’ otherwise.  Think of the photo you’ve taken out of a window somewhere, the outside looked lovely, but it basically had a black border.  Or the other way, where you just get a bright white window and a nicely lit room.  I’m aiming for a more subtle effect, and so my first requirement is as many exposures to work with as is practical.  The more exposures you have, the more choice whatever software you use will have to choose an exposure that is closest to what you want in every part of the image.  I generally take 7 exposures, from -3 to +3 stops.  That’s probably overkill, but I actually like the process.  5 (-2 to +2 in single stops) is usually plenty, and in most cases 3 exposures will get you fair results.  You can judge how much to bracket your own photos, but I’d generally go for +/-1.5 stops.

To go that step further and aim for your best photos, the points I stick to are:

  • Use a tripod (and don’t forget to switch the image stabiliser off).
    Using a tripod is the biggest step change you will see in the sharpness of your photos.  However, leaving the image stabilisation on will actually introduce tiny movements in the mechanism, thus introducing ‘softness’.
  • Focus manually.  If your camera has a live view and zoom mode, use it.
    Unless you have a camera with tens of focal points, and you’ve chosen exactly which one you want, then you want to be zooming in on exactly what you want to see and focusing manually on that.  Actually, never trust the auto-focus, it’ll end in tears.
  • Use a shutter release cable, or the short timer.
    As careful as you try to be, pressing the shutter button will introduce movement to the camera.  The timer can help with this but, especially if your tripod is set high, small vibrations can continue for several seconds.
  • Use the mirror lock up facility if your camera has it.
    We’re getting down to the slightly obsessive level now, but in an SLR camera, just before the photo is taken, the camera has to move the mirror out of the way.  That’s a solid lump getting thrown around in your camera and, yes, you guessed it, that’s movement right there.  The mirror lock up facility will add a button press to your process.  The first will move the mirror out of the way, with the second taking the photo.
  • Keep an eye out for gross movements in or out of your shot between exposures.
    While you’re concentrating on your camera, trying to remember whether you just did -1 or +1 stops of exposure, people are moving around.  People are generally very inconsiderate when it comes to your photography 😉  Make sure if there’s anything in the frame that you want it to be there.  If not, wait for it to move.  This is particularly relevant with fisheye shots.
  • Bracket using shutter speed, not aperture.
    My camera won’t automatically shoot 7 bracketed shots (it will do 3) so I switch the camera to manual and change the exposure myself.  When I haven’t been concentrating, I have been known to change the exposure by altering the aperture rather than the shutter speed.  On the back of your camera, the result will look like what you want, but the depths of field will be sufficiently different to cause unwanted results later on.

I think you should probably go and take some bracketed photos.  There’s lots of software out there to process HDR images for you, but come back in a bit and I’ll show you what I used to transform this photo.

Going Polar

One of the  things I like about the pixel stick is that you can get some really beautiful and complex patterns from what seem like very simple images.  The image below is simply a few circles overlaid in a row, spinning the pixel stick as you walk.  Rest assured, this wasn’t my first attempt.



Simplified conversion of a circular picture into a rectangular picture

Going polar

Playing with circles got me to thinking:  you could double the resolution of the image if you used one end of the stick as the centre of a circle and drew around it.  Obviously, if you take an image and just spin it around, that’s not going to come our right – though, thinking about it, I might give that a go as well.  So, without really knowing what I was looking for, I happened across the concept of polar coordinates.  I’m not a mathematician, I just like a bit of maths when it helps me do what I want to do, so this is my explanation…

What are polar coordinates?

What are polar coordinates?

Polar coordinates are just a different way of representing x and y coordinate but, instead of x, you have distance from a central point and, instead of y, you have the angle of rotation from a starting point.  Working on that basis, I wrote a little Python script to convert a 400×400 image into an image 200 pixels tall and 1260 pixels wide.  The circumference of a circle 400 pixels wide is 1257, and I wanted one pixel for each ‘unit’ of the circumference.  I rounded up to the nearest multiple of 4, because that comes in later.

If you’re not interested in trying this kind of thing for yourself, then you can probably just skip this section and look at any pictures at the end.  I’ve recently started programming in Python; I like its structure and simplicity.  I’m also a problem solver rather than a packager, so my code, in this case, is just run from within Eclipse, I haven’t packaged it in any way.  I haven’t exhaustively commented the code, as I’ll try to explain what I’m doing in the text.

'''If you use a variant of this code, please give me attribution by leaving this comment section intact.  This code is intended for use in converting a 400x400 circular image into a rectangular image that can be rotated around one edge to recreate the original.  It was created by Chris Geatch as part of  You can also find his photography on flickr at
from PIL import Image as im
import math

stick_width = 1260  #This is the width of the final image to load to the pixel stick

You’ll need the PIL library for image processing, if you don’t have it already.  There are all sorts of guides to installing it, so I’ll leave you to choose one for yourself.

def main():
 processImage("G:\\image path\\", "rbogrid.jpg")

def get_coordinate(stick_x,stick_y,centre_x,centre_y):
 angle = (stick_x / stick_width) * (2 * math.pi)
 return angle

 def processImage(image_path, image_name):
 image_title = image_name[0:image_name.find(".")]

 image ="%s\\%s" % (image_path, image_name),"r")
 im_stick ="RGB", (stick_width,200), color="#000000")

 for stick_x in range(stick_width):
 for stick_y in range(200):
 hypotenuse = 1.0 * stick_y #The distance from the polar centre
 quadrant = int(stick_x / (stick_width/4))
 theta = (((1.0 * stick_x) / stick_width) * (2.0 * math.pi)) - (quadrant * (math.pi/2.0))

 polar_x = round(hypotenuse * math.cos(theta))
 polar_y = round(math.sqrt(hypotenuse**2 - polar_x**2))
 if quadrant == 0:
 elif quadrant == 1:
 elif quadrant == 2:
 elif quadrant ==3:
 im_stick.putpixel((stick_x,stick_y),image.getpixel((200+polar_y,200+polar_x)))"%s\\%s_done.jpg" % (image_path, image_title), quality=100)

if __name__ == '__main__':

You know what? If you’re interested in programming, you’ll work it out, or you can ask. If you’d like to package it into an app and give me a copy, that would be just peachy.  So, having got to grips with some of the rounding errors inherent in the ‘extremes’ of trigonometry, I had a quick play with the results to see how they looked.  You may notice, my biggest problems now are:

  • How do you get the turning speed right?
  • How can you do it without holding the whole thing at arms length and hoping you don’t move?
  • The image gets a bit overexposed in the centre.

That aside, here are the less than perfect results, but I don’t care because maths is fun! 😉

Small yellow flower

The original

Flower image distorted for pixel stick

The 200 pixel high image on the pixel stick


Flower drawn with rotating pixel stick


There is a definite resemblance between the original image and the end result (though I’ve spun round in the wrong direction, so forgive me that).  As you can see, limitations on centring and speed.  All I’ll say is, this was not my first attempt.  So, since I had a few attempts, you have to sit through the second image as well.

150 years of Portobello and Golborne Market

150 Years Original

Pixel Stick image of Portobello 150 years


Pixel Stick Portobello rotated image

The end result, or as close as I got to it

It’s getting dark in the evenings again now – almost time for the next Pixel Stick project…

What am I thinking?

If you see me with a slightly glazed look on my face, there’s a fair chance my brain has gone off to do some maths.  Nothing super complicated, mostly stuff with triangles, I like triangles, but today it’s circles.

I got a new toy, a pixel stick to be exact.  A pixel stick is a 6 foot long bar of 200 full colour range LEDs, attached to a handle that allows you to spin the stick if you want.  You upload an image to it and then, while you take a long exposure, plays back the image one row at a time, ‘printing’ the picture onto the camera sensor as it goes.  Of course, once I’ve played with something for 10 minutes, I have to try to work out what else I can do with it, and this was no exception.

pixel stick image of hokusai behind a car

Hokusai wave breaking over a car

Here is one of my first attempts, using an example image that came with the stick (patience is not my strongest characteristic).  So, what else can you do?  Well, as you’re probably aware, I like to do a bit of maths mixed in with the photography and, as I was lying in bed with nothing to do, I was running sine waves and things through my head.  What happens if you rotate a sine wave around a central axis?  As it turns out, you get a circle.  And if you have four sine waves at regular intervals?

Diagram of how rotating a sine wave yields circles

Circles from Sine waves

Surprisingly enough, you get a circle in each quadrant of the overall spinning circle, each with a diameter half of the original circle.  I’ve tried to illustrate it to the left there.  At the beginning, the sine wave moves quickly away from the centre, but the centre of the stick moves slowly, so it doesn’t make huge changes.  As it gets to the edge, the rate of change of the distance from the centre is slower, but the outer edge of the stick moves quickly.  The net effect is that, for each cycle of the wave, two circles are drawn in the ‘right’ quadrant of the pixel stick.  So, adding three more staggered sine waves will give 3 more circles in the other three quadrants.  If you ever needed an excuse to love trigonometry… then you’re probably not as sad as I am.

Four staggered sine waves in rainbow colours

Rainbow sine waves

You end up with an image looking something like this, the rainbow is obviously in there because everything looks prettier in rainbow colours.  I’m not going to be able to surprise you with how it comes out, because you’ve already skimmed to the pictures.  I wasn’t really aiming to get four perfect circles intertwined, I wanted to see what it looked like repeating over and over.  Here’s the end result, I hope you like it.

Pixel stick circles on Brentford waterfront

Circular sine waves

To My Faithful Companion

There I was, sitting at home, supposed to be working, and I happened across a photo of my old travel companion.  Photography can be a solitary pursuit, I always feel bad if I’m with someone who has to hang around while I sit, looking like I’m doing a great deal, and half an hour later saying, “Okay, I’m done”.  But I have some understanding (or lazy) friends, so it usually works out okay.  I am, however, slightly eccentric (well, I like to think so), and so for those times when I was traveling alone, I befriended Boris, a young, ebullient, plush octopus, who accompanied me on many an adventure, until his head kind of split open and he was forced to retire to a shelf in the living room where, to this day, he still tastes like sea salt.
Back then, I think I had a Sony DSC-P1.  You know if a camera model number is basically “1”, it’s either a really swanky Canon, or really, really old.  Clearly, these photos weren’t taken on a Canon 1D, <sigh>.  Still, it got me thinking – Boris was always a great way of getting to talk to people.  Believe it or not, I’m not great at striking up conversationsBoris the octopus at Sydney aquarium with total strangers, but people liked to talk to Boris, well, maybe about Boris, not everyone is as weird as me (yeah, yeah, I licked a toy octopus, we’ve moved on from there, keep up).  I’ve had special attention (okay, in retrospect, perhaps not the right kind of special) at a few aquaria, and Boris has always been popular with children.  A group of them stole him in Montreal, and when you’re stressed and worried for your travel companion’s safety, it’s difficult to look sane running around shouting about your octopus in French.  Especially when you don’t know the word for octopus, yet.  “Poulpe” will be the last word of French I forget.  So, I’m thinking a new, young traveling companion may be the order of the day.  I found a lobster in the loft last weekend, but do I stay aquatic, or should I stay land-based.  As much as I love being in the water, I’m not going to have camera housing any time soon.  Any suggestions?

Boris the octopus snuggling up to Molly Mallone Boris the octopus, out with a mateI’m not sure there’s an animal out there that could so adeptly charm his way into the bosom of a young woman, or so easily form a friendship with any number of water-fowl.  In the meantime, my pet photography services are at your disposal.


What I’d want for Christmas (if I didn’t have two)

A long time ago, I thought that as long as you had a fast enough shutter speed, your photos would be fine and sharp, and look great.  If your lens had image stabilisation (IS), then you couldn’t possibly go wrong!  Then, I actually started looking at my photos.  How many times have you looked at the back of your camera and thought, “Ooooh, that looks good”, then got home and full size it’s more like, “Oh, not so great.”?  It happens to everyone, it’s (one reason) why we take so many of the same shot, but it needn’t be as common as you’re currently getting.  The biggest step change in my photography was buying a tripod.  Actually, no, the biggest change was using a tripod (it doesn’t work in the same way as having lots of books in your house makes you smart without actually reading them).  Automatic built in flash is also not your friend.  As pretty as it looks at a concert where all those camera flashes are going off, those people all go home with photos of brightly lit backs of heads, a lot of darkness and a very blurry something going on in the distance (okay, if you know how to use the camera you can get a bit better than that).  My advice is, put the camera away and enjoy the show.  I’m definitely not suggesting you take a tripod to a concert.

Interior illumination of the Palm House at Kew

2.5s, f/4.0, ISO1600

If you enjoy photography, then taking a little time over your photos is going to make you happy, I promise.  If you like to have a basic record of what you did that day, and you’re not so bothered about the details, then a tripod probably isn’t for you.  The Christmas at Kew event is stunning.  Sadly, I’m not paid to say that (65 of you reading this, surely that must be a week’s groceries in sponsorship!), but I’ll recommend it anyway.
This photo of the palm house is, hopefully obviously, taken on a tripod.  As the light was continually changing, I needed a reasonable exposure time, less than about 5 seconds, but didn’t want to push the ISO beyond 1600 (maybe I’ll talk about noise next time).  So, I had to keep an open aperture and go for a faster film speed.  Good saturation of colours without it just being a big blob of light, I hope.  Most cameras now have ‘live view’, showing what you have framed on the view-screen.  Some further allow you to zoom in on a part of that display (without changing the framing of your photo).  I use that to get the exact point of the photo I want in the best focus I can get.  If you’re really going for it, then SLR cameras (non-SLR cameras don’t have this ‘problem’) will have a setting in a menu somewhere to “Lock mirror up”, which means that, rather than move the mirror, take the photo and put the mirror back all in one go (so, technically, possibly introducing vibration movement), it will move the mirror on your first press of the shutter button, and take the photo on the second.  If you’re not using a remote shutter release, then use the timer, obviously (winter photos are much nicer when you can keep your hands in your pockets).

long exposure of Alberta Falls in Colorado

1.3s, f/8.0, ISO400

This final picture is taken with my favourite filter, an ND10.  It just looks like a black piece of glass (the filter, not the photo), and blocks light to make the required exposure 10 stops longer to get the same result as you’d get without it. That can take a photo down from and exposure of about 1/1000th of a second, to a little over a second.  I’m a sucker for a slow shutter waterfall, and this one was no exception, taken on a bright, sunny Autumn day in Estes Park in Colorado.  I could play around at waterfalls for hours, but on this occasion we were making our way elsewhere, and we had come equipped only with a bag of jelly apple rings, so energy reserves were on a tight budget, and we had to plough on as fast as we could.  If you’re visiting Estes Park, you have to do the Sky Pond trail, but it’s going to take you 6 hours, not 2.  Ignore the woman in the YMCA information centre, she hasn’t got a bloody clue!  And maybe take two packets of jelly apple rings, or even, like, some proper food.  Oh, and a tripod.