Friday, 18 July 2014

Choosing the right Colour Space

When it comes to the choice of a colour space for the digital photographer, you’ll find a great deal of confusion.  This is understandable because it’s a complex topic.  Actually finding the truth about colour spaces gets tougher simply because there’s an awful lot of mis-information about colour calibration circulating the ‘net.  So, it’s not surprising that many have no idea what a colour space is, or whether it’s of any use to us.

Definition: On a superficial level, a colour space describes a range of colours in a particular colour model. This model might be the RGB seen on all computer displays (i.e. sRGB) or it might be the model used to describe an offset litho press (CMYK).

Here's a standard colour model illustrating the different colours available through different colour spaces.
It also includes an indication of how matt printing paper reproduces colour - all four spaces have unique colour ranges.
To help understand this concept, a colour space can be displayed in three dimensions by showing cyan along the X axis, magenta along the Y axis and yellow along the Z axis (for example, from the CMYK print colour space).  This provides a 3D model demonstrating the range of tones possible through a combination of all three colour axes.

Though a somewhat childish analogy, printing is like using a palette of 24 crayons. But if you start out with 36 or 48 crayons, which ones go and which ones stay when you downsize from a wide gamut space to a narrower one...
On a purely simplistic level, a colour space is a bit like having one giant colour crayon set containing 75 crayons.  Let’s say this represents a wide gamut colour space like Pro Photo RGB.  To represent Adobe RGB, which has a narrower gamut (range), you might remove 25 crayons.  The smallest colour space used by photographers is sRGB so this might only have 35 crayons. (Note: The precise numbers here are used only as an illustrative tool).

The missing crayons in the Adobe RGB and sRGB analogy are not just from one colour region but, in the example comparison between sRGB and Adobe RGB, they come from the green/cyan part of the crayon box.  So looking at the 2D illustrations of what colours these different spaces represent, you can see exactly how much more green/blue Adobe RGB has when compared to sRGB, and how much more of the same colours ProPhoto RGB has over the narrower gamut Adobe RGB.

But before we get too excited by this newfound knowledge and rush to change everything to ProPhoto RGB, here are some basic colour space facts:
- ProPhoto RGB certainly does represent a very wide range of possible colours.
- sRGB however contains sufficient colour information for most practical applications.
- Most digital cameras only offer sRGB and Adobe RGB colour spaces in their feature set.
- Most consumer monitors can only display the sRGB colour space.
- Therefore you cannot physically see, let alone appreciate, the additional tones found in a broader colour space on a monitor.
- Most consumer printers can only reproduce colours from the sRGB colour space
- RAW files are definitely the best file format to use.  They save approximately five times the amount of image data as a JPEG.
- If the file is being used for the web it has to be converted to the sRGB colour space anyway, because that’s the default colour space for the web.
- JPEGs, because of their shallow bit depth, are always sRGB
If you digest the above facts, it would seem that most of our photographic lives work best in the sRGB colour space.  There seems little logical reason to set cameras to a colour space that produces a range of tones that cannot be displayed, nor seen correctly under normal viewing conditions.  It then follows that choosing a space that is wider than sRGB could be a waste of effort.
My thoughts on this are that it’s probably better to choose the sRGB colour space throughout your workflow.  Doing this ensures that at no time do you have to compromise what you can already capture, see onscreen or print.

Others espouse the benefits of shooting Adobe RGB and editing in that same space under the impression that they will retain the best possible outcomes.  I think this is a pipedream because at some stage in the edit process, you will have to compromise the colour space in order to output/upload to the web, to print (inkjet), or to publish (offset). 

So clearly when the colour space is reduced from Adobe RGB to sRGB, we need to mitigate any colour and contrast loss using very careful editing techniques.  To do this we have to investigate individual colour channels, something that you can do with Photoshop but not using Elements.

sRGB is the easiest and perhaps most reliable colour space in which to work because being the smallest, it presents few colour limitations (and fewer nasty surprises) when outputting to the web or any kind of consumer print.

Adobe RGB is a wider space - but care must be used both at the editing stage (to preserve colours when downsizing to sRGB for print) and especially so once the file is being handed off to a third party simply because there's guarantee that the person receiving the file knows what they are doing either.

ProPhoto RGB can encompass a huge range of colours but great skill is required to process these files in order to retain otherwise fragile tones once the file is output to the web or print. You can retain much of this space’s colour gamut in print but this also requires both high-end printers and skill in executing the process.

Thursday, 10 July 2014

Golden Gully, Hill End - Rainy Day Photography

Although I had been to Hill End before, I had not heard of Golden Gully till this trip. Just out of Hill End, close to Tambaroora, Golden Gully is a small ravine where gold was discovered in the 19850s. You can easily climb down from the main road to the base of the ravine and wander along the small stream. When we were there is was bitterly cold and raining. Even so we met two characters who were busy gold panning in the creek.
The gully is probably 30 feet deep and features a large natural arch and multiple diggings into the ravine sides. Not the sort of place you'd want to get caught in during a flash flood.
As you can see from this shot, the light was poor and the photo results very dull.

This is a triple exposure put together as an HDR shot  using Photomatix Pro and sharpened.
Some hue and saturation adjustments have been made to bring out the colours.

More work is required.  In this frame I used the Burn brush set to Midtones to darken both the edges of the frame as well as the darker parts of the image.  Doing this not only brought out the colour in the ravine walls but it also served to highlight the tracks into the gully.  Burning-in the shadows and Dodging the highlights has the effect of increasing local contrast and is a very effective way to bring out the tones in an otherwise dull-looking image.

Wednesday, 11 June 2014

Ethiopia and Rwanda Photo Tour now on sale - Feb 2015

My tour starts in Feb 2015 (20 - March10th) and travels from Addis Ababa to Bahar Dar, Gondar, Simien Mountains, Axum and Lalibela for 16 days of stunning scenery, amazing architecture and fabulous, friendly people.  The tour is organised through Academy Travel in Sydney and features some unique destinations and experiences that will make this a truly unforgettable travel experience. 
As we will be in the region, I decided to add on a Rwanda tour component at the end of the trip  (it's a relatively short hop from Addis to Kigali airport).  Of course you go to Rwanda to see the amazing mountain gorillas, an unforgettable experience, but the country is also a fascinating destination, with its tragic recent history contrasting with it's current determination to develop a stable economy.  Here are a few fantastic photos from Ethiopia taken earlier this year  - shot by my good friend Sue Burt. 

Overview, the Simien Mountains
Another panorama of the magnificent Simien Mountains
The Simien Mountains, home to Gelada Baboons, Mountain Nyalas, Ibex and the rare Ethiopian wolf
Fasilides Castle in Gondar, one of the many structures in the town's historical area
Priest in Lalibela
Two priests guarding the art relics at one of Lake Tana's island monasteries
Visitors to one of Lalibela's rock-hewn churches
Ethiopia is famous for its plentiful religious ceremonies. This is the ceremony of Timcat
Impressive sunset view of the Simien mountains
View flying over the arid expanses of Northern Ethiopia

Tuesday, 3 June 2014

Photographing Vivid's Amazing Light Show

Vivid is back with a vengeance this year, with a bunch of new venues and impressive lighting schemes.
This is a 30-second exposure of the harbour bridge taken with a 14mm fisheye lens. 
The long exposure renders shifting water as an ultra-smooth surface with exceptional reflections that the naked eye doesn't register...
The ultimate zoom shot?
One of  Vivid's smaller light shows along the harbour foreshore zoomed slowly for about five seconds.
First night this was one it was soooo crowded the authorities were forced to fence of the arena and let small groups in at a time.
Good move for us photographers because it was then easier to get clearer shots of the floor mounted lighting.
A cloudy night adds another dimension to any nighttime shooting situation.
In contrast, a clear sky leaves an almost jet-black night sky which looks heavy and overbearing. 
Clouds add a different dimension, with movement and a fair amount of ambient light giving an otherwise black sky an added depth.
Architecture and big structures need photographing with a very wide-angle lens, better still, a fisheye lens.
Ultra-wide angle lenses give a unique perspective on otherwise impossible-to-get subject matter.  Canon EF14mm lens, f11, 30 secs, ISO 400.
Sydney Opera House ten minutes before the sky turned almost totally black.
Bracketing the exposures (approximately at 30secs, 10 secs and 4 second exposures) gives the HDR software (in this case Photomatix Pro) ample opportunity to create an impressive result that's unobtainable with a single shot...
To get over that black night sky look, have a bit of fun combining a daytime exposure with a nighttime Vivid exposure...
HDR photo of the Opera house just before dusk.
Note shadow of Harbour Bridge falling over the Opera House sails
Zooming in on a Vivid illumination often adds a new visual dynamic to a composition.
You need a steady tripod and a one, two or three second exposure (i.e. long enough for you to physically zoom the lens)
Sydney's Customs House in all its Vivid glory
One of the harder subjects to record - Sydney's Luna Park.
Because the Park is mostly bright lights and deep shadows, all cameras overexpose the subject.  Basically you get a blown-out image that's unusable. 
The only way to record such a high contrast scene is to bracket the exposures dramatically underexposing the darker frame considerably so that, once re-combined in Photomatix Pro, the final image retains details in the highlights.
Cloudy skies add a layer of ambient light to any long exposure shot brings more life to the scene (this is 25secs).
A long exposure also smoothes-out ripples and adds a mirror-like shimmer to normally choppy water...
Long exposure shot from the upper deck of the ferry on the way home. 
This is a bit of as hit and miss process. I treat it like light painting.
Hold the camera stable and allow the movement, in this case the ferry, to paint the light across the sensor. Four seconds exposure, f6.3, ISO 200
Slow zoom of the Harbour Bridge. Five seconds @ f5, ISO 200.
Camera has to be on a stable tripod. Start moving the zoom ring - then trip the shutter to get this eye-catching special effect
Fisheye lenses produce the least distortion when held on the level to the horizontal - tilt them up or down to bend that horizon line, in this case significantly to produce a wacky special effect (pic by Natalie Hitchens). 14mm Samyang fisheye lens.  
More impressive zooming effects from Natalie Hitchens (1) 
More impressive zooming effects from Natalie Hitchens (2)