Last week I returned from a trip to Perth, Western Australia, where I explored the city and the outer suburbs, as well as drove up and down the coast a bit. This was the last major Australian city I hadn’t really spent more than an afternoon in until now (I’d previously twice spent a night in Perth, once due to a flight diversion), and I also managed to spend a day on Rottnest Island and saw some of the quokkas there.
The weather was reasonably good, and I managed to take quite a few photos, which I’ve just finished the initial run of processing, although it turns out my EF 24-70mm f/2.8L II lens has started having minor (but quite noticeable when looking at the images on a large monitor) issues with focusing, which is a bit annoying. It means a fair number of the photos aren’t as sharp/focused as they should be, so I might need to have the lens looked at if it continually has this issue in the future.
I’ve finally got around to finishing pretty comprehensive support for “remapping” pixel values from images within my image-processing infrastructure, so as to be able to scale or remap pixel values in an image to another representation.
It supports both “linear scalar” scaling, as well as scalar-to-colour (i.e. to an HSV gradient ramp) and scalar to custom configurable colour gradients,
in addition to being able to do additional pre-remapping scale and fit value modifications - i.e. re-fitting values from a data value input range of [-5000.0, 20000.0] to [0.0, 1.0] first and then applying scalar-to-colour gradient remapping afterwards.
This was mainly for two particular use-cases I had: the first was some more map visualisations I’m playing with - in particular some data on Global Shipping Traffic Density from the World Bank, where I got a bit frustrated with QGIS’s gradient-remapping functionality, so decided to roll my own in order to allow it to be more recipe-based with configurable parameters and then allow remapping multiple images with exactly the same params more easily.
Below is an example of remapped Global Shipping Traffic Density around Europe, with the reprojected (in terms of map projection) absolute values from the source file data being remapped to a custom colour gradient output image:
The second use-case was remapping 8-bit greyscale values in JPEG files taken from a thermal camera I’ve had for a while, to be able to remap them to more interesting and configurable colour gradients.
Original thermal camera image:
Remapped image:
Original thermal camera image:
Remapped image:
The thermal camera I have does support some colour gradient automatic remapping itself, however there are only 8 presets, and the result is baked into the captured JPEG image, so having the flexibility to capture in greyscale in the camera and then remap the images later is much more useful.
I do have some older interesting images I captured just after getting the camera years ago, where I was mostly capturing the images in pre-baked gradient format, which I would like to change the gradient of - so a possible feature improvement to my image-processing infrastructure might be to add support for “reverse-mapping” the colours in images from a gradient back to a “scalar” or linear value, so I could then apply custom colour gradients of my choosing.
A week ago I returned from a week’s trip to central New South Wales in Australia, driving from Sydney down to (almost!) Batemans Bay, then up again to Newcastle and then back to Sydney.
The aim was to spend a bit more time exploring places I’d skipped / missed when I motored through quickly on my trips passing through NSW in 2018 and 2019 - which I did end up doing, however it turned out I’d forgotten I had actually visited some places before! Jervis Bay Territory in particular - although this time around it wasn’t overcast, so I was able to see it (and the white sand beaches) with the sun out.
The weather was excellent, and once again I got some photos I’m pleased with.
Last week I implemented support for generating very simple (grid only) collages from photos/images in my image processing infrastructure.
I had wanted to create some simple grid-based collages of some photos, and I was somewhat surprised to discover that neither Krita nor GIMP (free/open source image manipulation software) seem to provide any built-in functionality to generate this type of output, without manually setting up grids/guides and resizing and positioning each image separately - which while not difficult in theory - is somewhat onerous, especially when you want to generate multiple similar collages from different sets of input images in a procedural/repeatable way.
I did briefly look into (free) web-based solutions, however I wasn’t really happy with that avenue either, partly due to most web solutions having the same lack of procedural/recipe generation (i.e. being able to just change the input images and get the same type of result without re-doing things from scratch again), but also because many web solutions seemed more targeted at “artistic” collages with photos having arbitrary positions and rotations, rather than having grid presets, as well as the fact that many (although not all) of the web apps in question required some form of registration or sign-in.
So I ended up just quickly implementing basic support for this collage generation myself in my image processing infrastructure, which took less than two hours, and means I can now generate arbitrary grid collages from a ‘recipe’ source parameters file which configures the target output resolution, the row and column counts, input images list, inner and outer border widths and border colour, as well as the image resize sampling algorithm/filter to use (i.e. bilinear, bicubic, Lanczos, etc) for resizing the input images to fit into the collage grid.
Over the past few months I’ve made some attempts at timelapse photography, mainly motivated by seeing this site/software on High Dynamic Time Range Images which effectively “blends” multiple images taken at different times into one final image.
Rather than use the above software (which is written in Perl), I decided to write my own implementation using my existing image processing infrastructure I have, and have so far come up with a simple implementation that supports linear “equi-width” blending, and in the future I plan to implement more varied interpolations similar to the original software, as from experimentation, Sunrises/Sunsets and the progression from day to night are not often linear in the resultant brightness of captured images.
Scenes with many lights in that progressively turn on within the timelapse duration seem to work very well generally: here are two examples I’m fairly happy with, showing both non-blended and fully-blended examples of each.
San Francisco:
Wellington:
There do though appear to be some types of scenes that don’t always seem to work that well with this technique, in particular ones where the sun is either quite prominent or the sky gradient in the horizontal direction is very noticeable: this can lead to “odd”-looking situations where the image “slices” which show the sky should in theory get darker as you progress through time, but due to the sky colour gradient in the source images, it counteracts this on one edge of each image slice, looking a bit weird (at least to my eyes).
I also tried converting a sunrise timelapse sequence I took several years ago in Australia which had clouds moving very slowly across the sky horizontally in the frame, and this produced what almost looked like an artifact-containing/repeating-pattern image (it was technically correct and valid though) in that the same bits of cloud were repeatedly in each image slice by coincidence due to their movement across the sky being in sync with the time delay between each subsequent image.
Other things to look out for are temporal position continuity when blending (see the Wellington blended version with the boat masts moving between captures above), where things like people, vehicles, and trees vary position over time, meaning the blending leads to “ghosting” due to the differing positions in the adjacent images which are being blended/merged together.
Two weeks ago I returned from a trip back to the UK for a few weeks, stopping off in San Francisco for a few days on the way out, and I have almost finished processing the DSLR photos I took, so this is just a quick post containing a single photo each from some of the locations I visited whilst away.
Last week I spent a few days down in the South Island around Queenstown and Wanaka, mainly to try and photograph the Autumn Colours. Apparently the term for this is a “Leaf Peeper”!
I’ve been several times before, but always in Spring or Summer, so this was the first time I’d seen any of the South Island in Autumn.
Whilst there is a bit of colour in Autumn in the North Island in places (in parks north of Wellington for example), there’s not much that I’ve seen in general (at least in comparison to the Northern Hemisphere), so it was a nostalgic memory of Autumn in the Northern Hemisphere, seeing the very widespread colours that occur there and I grew up with.
I think I’m correct in saying that almost all of the trees in New Zealand that have leaves which change colour in the Autumn are “exotic”, non-native species that have been imported from Europe, North America and Japan, with there being very few native deciduous trees (most are evergreen), and of those very few of them actually change colour.
Maples, English Beech (the native New Zealand Beech species are evergreen from what I can tell), Gum, Cherry and Horse chestnut trees seem almost certain to have been imported by early settlers, and the fact they seem to mostly be found along rivers and near settlements rather than being found out further away in more remote parts of the landscape seems to re-enforce that theory, but it’s difficult to know for certain.
Regardless, they do provide a very noticeable splash of colour on top of New Zealand’s already beautiful scenery in the area, and I did get some nice photos I’m happy with.
I’ve just got back from a fantastic week and a bit in the South Island, and was very lucky to have perfect weather for most of the trip, as well as getting a lucky view of the Aurora Australis (Southern Lights) one night.
I was in Queenstown at the time, and a phone app I have which gives notifications when Aurora might be visible at your location alerted me that it was likely visible, so I grabbed my camera and tripod to try and photograph it, starting during the later stages of dusk. There were two different “types” that were fairly faint but just visible to the naked eye: a green glow that really looked like light pollution - although there were no large towns in exactly that direction, and it morphed over time changing shape - and blue streaks, gently pulsing over time.
With a long exposure, they are much more clearly visible.
A very magical experience.
I also managed to get some excellent views of Aoraki / Mt Cook.
No matter how many times I see stunning sunsets, I never get bored of them. Similarly with photographing them and looking at the photos afterwards: even though they can to some extent technically be repetitive when looking through photos of them later, there’s just something I find very magical and awe-inspiring about them.
I spent the second half of last week on a short break in the South Island based mostly in Christchurch, although I ventured out a bit to the wider area of Canterbury. The weather was excellent for landscape / travel photography, and I managed to get some pretty good shots of snowy mountains, and for my third trip to Banks Peninsula finally got to see it in nice weather (although once again got the timing of the tides wrong as I often do!).
The general lack of international visitors / tourists was pretty pronounced, even in normally popular tourist spots.
