Friday, 23 December 2011

Exercise: Colours into Tones 1

This exercise is all about being able to identify a scene through colour and being able to translate it into tones in a black and white image. For this we are to find an image that has a strong contrast in colour, I chose the following image for its contrasts in red and green, colours that are opposite. The reds are very apparent in the red leave autumnal tree and the brown hues in the foreground plant. The greens are present in the grass and background trees,

Below is the standard conversion using the Photoshop Channel Mixer. This sets a balance between red, green, blue of +40,+40,+20 respectively. Here the red leafed tree is almost lost in the conversion, as is the foreground, leaving a rather bland conversion.

So the first thing is to bring out the reds by boosting the red channel to +106. To counteract this the green channel has been reduced to -83 and the blue channel boosted to +81. This has brought out the reds, and darkened the greens. The effect of the blue slider has helped to brighten up the image and retain a neutral sky tone. Overall this has made an image with good contrasting tones.

The opposite effect has been achieved by reducing the reds to -16, darkening the tress and foreground, the green slider was boosted to +188 which has lightened the grass and green foliage.This has however merged the red leaf tree and the background tree into an indistinguishable lump. Finally the blue slider was reduced to -3 to compensate for the boost in green and to retain that overall sky tone.

Again I think that this was worked well, but with the loss of the reds, it makes a less interesting image.

Exercise: Strength of Interpretation

This exercise explores how an image can change in colour and tones through varying strengths of contrast or saturation. We are asked to take two images that would be open firstly to a strong increase in contrast, and secondly an image that would be able to be boosted in either the high lights or the low lights. For each image we are then to produce a colour and black and white version.

The first image is that of an old brick built tower. I chose this image as I know that bricks look great under an increase in contrast, they seem to make the building stand out by defining each stone as an individual unit, rather than a bland brick wall.

The first colour image is by no means a fair representation but the brickworks colour has intensified so much that it really does look burnt in. Having the cloudy sky in the background has added to the contrasting effect.  Inevitably there will be shadow clipping in the bottom of the image, but for this type of image I think it works well.

When converted to black and white the contrasts seem more balanced and authentic, again the brickwork looks great making the building look more foreboding, older and eerier. I prefer this version. All adjustments were completed in Photoshop using a curves layer with a heavy 'S' Curve, and another Channel Mixer layer to convert to black and white, with some minor adjustments to the levels of RGB.

The second image was taken last summer of Southwold Peer. This image was taken late in the year, around October November on a sunny day. The original image was well balanced but by increasing the highlights (giving it a high key effect) it has given the image of a feeling in summer on a bright hazy day.

I am not sure which version I prefer, but I think I am leaning towards the colour image, the black and white looks as if it really needs a boost in contrast, whereas the colour version looks more acceptable. This was an interesting exercise and although I boost the contrast in many of my images, especially for B&W versions, I have never given, or thought to give any image the high key treatment.

I suspect that portrait images of a small child or a woman would also benefit from this as it really does soften the image as well.

Wednesday, 21 December 2011

Steve McCurry

Whilst looking at photographers to inspire me, I cam across the infamous name of Steve McCurry, a photojournalist that studies people in their natural environments, especially those in India, Afghanistan, the Far East and in some cases at home in the USA.

His use of colour is probably the most striking aspect of his work. He claims to take thousands of photographs, and he sure has plenty of work published, perhaps I too need to take more?

I bought two of his books, 'The Unguarded Moment' and a collection of portraits, entitled 'Portraits', with the iconic image named 'Afghan Girl' on the cover.

The unguarded moment is capturing everyday human life, and concentrates on images from India, Afghanistan and the Middle East. All of the images are inspiring, the colour and tones are perfect,'Dust storm, Rajasthan, India' captures an amazing image of women sheltering around a tree with brilliant reds and an orange hue in the storm. I wonder how much the colour of the sand and storm has been manipulated, perhaps nothing at all, but a video on you tube with Steve describing this shot is more grey and therefore I think this has been boosted for the book. There is also a very interesting collection of points of people creating rhythm in the image

This image and a narrative are from Steve's Blog at

Other images that took my eye were the Ship breaking in Karachi, with the immense sense of scale of beached ships  being dismantled by hand and the portrait of Aung San Suu Kyi taken in Rangoon, Burma 1996, and inspiration to many for freedom.

I could go on forever about the many images of children, looking like rabbits caught in the headlights of a car, but one of his more famous images ' Boy in mid-flight, Jodhpur, India' is the reason I bought this book. again a narrative from McCurry gave away that he waited all day in this lane taken hundreds of images just to capture this split second, a moment in time......

Thank you Steve for the inspiration.....

Sunday, 18 December 2011

Exercise: Black & White

This exercise explores the interpretation of a subject with a view to making a black and white image.

The scene I chose had several elements that I thought would work well in Black & White. Firstly, the sky was a good deep blue colour which could be darkened or lightened and the clouds burned in more for a more dramatic effect.

The gravel path and fence posts would look good with a high contrast applied and finally the trees already have a great level of shadow detail and highlights which could be brought out more in black and white.

To begin the processing I converted the image to b&w in the raw converter. I then adjusted the sliders to make the blues darker, I did the same for the yellows and greens a little to darken the grass. Finally to lighten the path a little I reduced the reds slightly.

Once open in photoshop, I used the burn tool at 3% exposure to burn in the shadows and mid-tones concentrating on the sky, trees and grass.

The bottom right hand corner needed a boost in contrast, so with a selective levels adjustment I boosted the contrast.

Finally I used the dodge tool, again at 3% exposure, to bring out the highlights in the trees, clouds and the sheep, also paying attention to the pathway.

I think that the resulting image is certainly aged and produces a pleasing version that is more interesting that the colour version.

Exercise: Interpretative processing

This exercise is all about making interpretations of an image for creative purposes. We are asked to take a single image and using the processing software available, make three interpretations.

The first image has very little adjustment from what was seen, slight adjustments were for exposure and contrast. The image was taken later in the later on on a clear summer's day.

The second image was an attempt to make the landscape more barren. For this I reduced the exposure by about half a stop, and using the raw converter I  moved the yellows slider from green to orange. This has resulted in the mid ground desaturating the greens and giving a more rusty look to the ground. The sky too was slightly adjusted to give a stronger colour as if the image was taken at a higher altitude.

The final image was an attempt to make the image look later in the day as if dusk has fallen. I reduced the exposure and adjusted the temperature to reflect a murkier tone.

I feel that overall the last image has worked least of all, it does look murky, but then it also looks poorly taken. I think that the middle image has work better as an interpretation of a more desolate environment.

Tuesday, 13 December 2011

Exercise: Managing Colour

This exercise is all about getting the right colour balance within an image. We are asked to find two of more images that have a definite colour cast and to use the RAW converter to correct this cast, or if using a JPEG image  to use 'grey dropper' tool within the levels or curves adjustments.

I chose the first raw image taken under fluorescent lighting with the camera set at auto white balance. The squash courts were actually a pastel yellow, as opposed to white walls, and this has helped to give an ugly yellow cast over the image, which is also under exposed slightly.

To correct this image I first changed the white balance setting to fluorescent, however it still need a minor tweak with the temperature and tint sliders to give an overall good colour balance. I used the white of the shoes and the player's T-Shirt as indicators. After adjusting the exposure and brightness so that the image has full dynamic range I then felt that the colour had been corrected.

Although taken in RAW I have used the following image to show similar results in a JPEG. This image was taken on a sunny day with AWB but from recollection, and the shadows present, it could have been taken standing in shadow. Either way it has led to an unpleasant magenta cast to the image.

To correct this I created a levels layer in photoshop and used the grey dropper tool to click on the grey concrete payment in the background. This instantly shifted the colour balance to a very acceptable version.

As a separate exercise I also corrected the same image in the raw converter simply by changing the white balance to 'Sunny' and boosting the contrast to produce the following version, which is far better than the jpeg conversion.

Exercise: Managing Tone

Managing tone in images is something I have been doing for a while, but I am now starting to realise some of the mistakes over the years. Firstly I relied on it too much, and now concentrate more on the camera settings, lighting conditions and framing. Secondly I probably made too many adjustments and too hard at that, this can be seen in many of my past images during the 'optimisation' stage.

In this exercise we are to take an image, and by using the available options during optimisation, make the very best image possible. These would include the main sliders in the RAW converter so that it would leave very little or no further adjustments necessary. This would of course preclude cloning, layers etc.

For this exercise I took an interesting but rather flat holiday picture, the original of which is shown below. It was a sunny day, with a lot of light reflecting off the water. The image was shot with AWB, ISO 100 at f/5.6, 1/125 sec exposure. The image has a slight bit of over exposure on the lower right hand side, but not too much. It does however have very little in terms of darker areas and contrast as shown in the following histogram.

The first change I made was to change the white balance to sunny. This gave slightly more contrast to the image and a greater colour depth. Overall colour cast looks acceptable, so I left the temperature and tint sliders as is.

Exposure of the image is fine except for the small amount of clipping which I removed using the recovery slider. To increase the shadows I increased the blacks slider to +12, just as shadow clipping was starting.

Brightness looks good, but the image still lacks contrast so I adjusted this slider so that it appeared to my eye more acceptable. Finally, I increased the saturation and vibrance sliders slightly to boost the image's colours in the water and the red's in the huts, this has also helped to increase the contrast a little. Finally the image was sharpened at an amount of 52 radius 1.0 px leaving the following image with a histogram spread distributed to the limits.

Saturday, 10 December 2011

Exercise: RAW

In this exercise we are exploring the power of using the RAW format when taking images.

As a comparison we are to take images of three scenes, daylight, high contrast and artificial lighting. For each scene we are to shoot in both RAW and JPEG. The camera should be set up as optimal as possible so that the JPEG image is shown in its best light, this would include exposure and white balance.

Using a RAW converter we are then asked to process the image as best as possible and note the differences between the RAW conversion and the standard JPEG.

The first image was taken a week after Remberance Sunday at a local small memorial. The sun was starting to set and I chose a white balance of sunny with and exposure of 1/80 sec at f/5.0 ISO 100. This was a fairly good exposure but there was a small amount of highlight clipping on the cross. Adjusting the recovery slider h compensated for this in RAW.

The Temp and tint was also adjusted slightly so that the quite overpowering colour of the poppies was brought to a realistic shade, something that the JPEG has failed to do. Finally a small amount of additional contrast  was added. This has also warmed up the image reflecting the warmth in the sun at the time of shooting.

Looking at the small images there is not a great deal between them indicating that the camera settings were not to far out and the image was reasonably exposed.

The first image is the original JPEG followed by the RAW conversion.

The second set of images were the high contrasting images, take of a dark car's grill. This was an interesting conversion. The original image had a lot of under exposure leading to shadow clipping. When this was removed the image became 'grey and flat' but the grill could be seen clearly. further adjustments for the contrast and adding a high contrasting tone reset the image to something like the original but without any highlight or shadow warnings.

Finally the white balcance was adjusted to give a cooler looking image which I think adds more impact.This did leave the edge of the number plate with a blue tinge so I used a selective mask in Lightroom and reduced the saturation

The final set of images were taken indoors using a tungsten lamp. The camera's white balance was set for tungsten and the histogram checked for correct exposure.

The camera did well to compensate for the colour cast as seen in the first JPEG image. It was felt that the colour was a little too warm and this was adjusted using the temperate and tint sliders in the RAW version to reduce the colours to a more realistic level. A small curve was then added to boost the contrast a little.

Overall there is very little difference in the two images, perhaps just the minor adjustments and added constant has made the RAW conversion slightly better.

Tuesday, 25 October 2011

Exercise: Colour cast and white balance

In this exercise we are exploring the varying colour temperatures given off by the sun in different circumstances such as time of the day, clouds, shade, sunshine and the interaction with artificial lighting. A key point I want to note is that although temperature increases with heat (degrees kelvin) the 'colour cast or colour temperature' of blue (around 10,000k) is a higher temperature that that of a setting red sun (3000k), and white light (12 mid day in sunshine) being somewhere in between the two at 5500k. An interesting comparison made in the notes was certain elements as they increase in temperature turn from red to white to blue.

We are to find scenes in sunlight, shade on a sunny day and cloud and take four images of each with the camera set for white balance settings of auto, sunlight, shade and cloud noting the difference.

The first set of four images were taken on a cloudy day.

I chose these coloured pegs as I thought varying settings would make a difference but there is very little. If anything the Cloudy setting is less intense and therefore probably more true  in terms of colour but I like the brighter more intense colours of the Shade WB.

The next set were of those in sunlight, taken at around 11 am in early Autumn.

Again the relevant setting seems to be more accurate, that is the daylight setting, or sunlight setting does not have a red'ish cast compared to the others, albeit warming up the scene nicely. As it can be seen although the sun was shining there were clouds about and the Cloudy setting has also worked reasonably well, perhaps better than the Auto setting.

The final set were taken on a sunny day in the Shade or part shade. Here there are seen more dramatic differences.

The Auto setting definitely has a blue cast to it and is not the best version by far. I was surprised to see that the Shade version has tried to compensate for the Blue Cast but warming up the image, but a little too much, almost as it it were in sunshine itself. The Cloudy WB probably reflects the most accurate and pleasing image here.

The second part of this exercise is to take three images using a white balance of auto, sunlight and tungsten at dusk where both the inside and outside are visible with the interior lit by incandescent (tungsten) lighting. This required a tripod as the shutter speeds were around 1/4 second.

The daylight setting certainly has warmed up this image, a little too much though. The auto setting has too warmed up  the image but not quite as much. The tungsten setting has good neutral inside tones but at the cost of producing a blue cast to the outside particularly on the edge of the panes of glass.

Finally we are asked if using RAW to look at adjusting the white balance sliders to see if there is a compromise. If found that by adjusting the temperature from 3150 to 3400 and the tint from +4 to -12 gave the best results. This would warm up the image and increase the green of the background foliage respectively.

Monday, 24 October 2011

Exercise: Your camera's dynamic range

This was an interesting exercise to determine the dynamic range of our camera, mine is a Canon EOS 40D. To measure the range we are to set up a scene in sunlight with a piece of white card to provide the highest relfectance and hence the highest highlight. The scene should also have a dark area  with detail, I chose a summerhouse in sunlight where the windows were almost black but able to see some detail, I used a piece of A3 card and placed it in both shade and direct sunlight.

With the camera set at 1/800 exposure at ISO 100 with all noise reduction off, I found that an aperture of f/4.5 just prevented the camera's clipping warning on the white card, signifying the brightest part of the scene. This image is shown below.

We were then asked to measure the brightest part of the image and two or three dark parts. I changed the metering of the camera to spot and zoomed into the card which measured f/11. The lowest part of the image I measured was f/4, this however was also on the limit of the lens I was using but seemed to be a good reading.

With the image open in Photoshop I used the colour sampling tool to measure the RGB channels on the card, these were almost at the maximum with typical readings on all channels in the 25x range showing that there was no burn out in the image and it was indeed exposed as best as possible.

To find the lowest exposure capable of the camera I opened the image in RAW and turned off any noise reduction and zoomed into the darkest part of the image. Adjusting the exposure slider so that the dark areas were lightened until the level of noise introduced could not be distinguished from the detail. Here is a snapshot of that scene. The noise introduced on the wood is not not distinguishable with the detail.

This adjustment gave a further 3.5 stops. This only gave my camera a total dynamic range of 6.5 stops, reading online literature it is actually around 8.5 stops, but I think that although this exercise shows how to judge the dynamic range it is probably not as accurate as the testing methods I have reviewed. If time permits I will repeat this again with a lens that has a lower f-stop, I think that is probably where I lost a couple!

Monday, 10 October 2011

Exercise: Sensor linear capture

This was an interesting exercise to see how light that falls on the camera's sensor is processed within the camera. Light is treated linear for the camera's sensor and most of the captured light is towards the the left of a histogram in the dark areas. To compensate for this the camera applies a gamma correction to boost the highlights and mid tones, effectively shifting the histogram to the right. This gives an image which is close to what the human eye would have seen.

Here is the original with a copy of the histogram.

The following curve was applied to this image to bring it back to what it would have looked like before the camera applied its gamma correction.

This has made the image a lot darker with the histogram bunched up to the left.

The key part to note here is that the majority of the available levels above in the histogram are used in the brighter part of the image, this part of the histogram that is in the right half. This means that there is less available for the darker tones to work with that are all scrunched up on the left, this leads to lesser sampling which will introduce artificial effects such as noise.

By applying the following curve we are emulating the processing of the camera to the linear image. This has restored the image to something near the original, but during the process has introduced additional noise in the areas that it has boosted, notably the shadows.

Although these changes were made with a 16 bit resolution an interesting point to note that is not mentioned in the notes is that the number of samples on the left (shadows) is now significantly reduced, and will therefore inherently introduce unwanted effects.