Colour Cast and White Balance

17/7/13

Part 1

This part of the exercise looks at what happens to the colour of the image when the camera decides what the white balance should be or when control is taken and the white balance is set by the photographer. I had a basic understanding of this through a similar exercise in TAOP 1. 

The camera’s auto white balance (AWB) works between 3000K and 7000K. Sunlight is measured at 5200K, Cloudy at 6000K and Shade at 7000K (Canon 1000D) . So when selecting AWB, the camera will set the lighting somewhere in that range. It is interesting to note the variations between what happens when I set the white balance to when the camera sets it. Freeman (2011) describes how the AWB works, “Automatic White Balance requires the camera’s processor to analyse the scene, identify highlights and adjust the overall balance, and for most situations it is a good choice.” I would agree with this statement up to a point, because when comparing the AWB to the actual situation, the image is fairly similar. I have found on closer examination of these images, that AWB does not always bring out the best in the image.  I have highlighted my favourites with a black border.

Sunlight

Auto White Balance         Sunny
    

Cloudy                            Open shade on a sunny day
    
All images 1/180 F5.6 ISO100 80mm 
        

Out of these four identical images, there is variation between the colour casts. My favourite is daylight which is the conditions under which I took this set of images.  I think it shows the warmth in the stones without over exaggerating it. The colour looks as I remember it to be.

With the other three, AWB is too grey and lacks some tonal range. There appears to be more definition in the shadows. The greens and grey tones are picked out. Shade appears too orange and areas of sunlight are very bright. Cloudy sits half way between the daylight and shade. The bricks show the warmth and are still very orange. The shadows seem well defined.

Cloudy

Auto White balance         Sunny
    

Cloudy                           Open shade on a sunny day
    
All images 1/500 F2.8 ISO100 70mm

I prefer the cloudy white balance in this situation.The colours are representational of what I observed.  The sunny image makes the colours quite grey/blue and the image appear flatter. The AWB is similar to cloudy and worked well on this occasion and  the shade emits an orange colour cast over the scene.

Open shade on a sunny day

Auto White Balance         Sunny
    

Cloudy                             Open shade on a sunny day
    
All images 0.7secs F11 ISO100 24mm

Here I actually prefer the cloudy version. The reason being that the AWB colour tones are very grey/blue and has no warmth in the image. The scene looks quite flat. The brown in the shade white balance is very brown and the highlights look unnatural. The cloudy white balance image seems to capture the colours as I remember them.

Part 2
The second part of this exercise involved finding a mixed lighting scene. Having looked at an interior looking towards the outside in TAOP 1, I decided to experiment with a candle and daylight at in the evening. This gave me a bluish tinge to the daylight as it became dusk and the candle glowed orange. I thought it would challenge my camera as candlelight is about 2000K, so unless I set the white balance manually, I would have to achieve the right colour temperature with the presets  between 3200K (Tungsten) and Daylight being 5200K. Knowing that fluorescent  was between daylight and tungsten, I decided to include this also to see what the results would be.

Auto White Balance         Daylight 5200K
    
Tungsten   3200K             Fluorescent 4000K
    
All images 0.5secs F4 ISO100 35mm

I think the most pleasing image is the AWB image because the daylight has a slightly blue cast to it.  It is almost as if the camera has warmed up the scene. Tungsten and fluorescent both give a blue colour cast to the image. The only part of all four images which remains very similar in colour is the orange glow from the candle.

I also experimented with the candle and holder on its own as it became darker. I was interested to see what happened if candlelight was the only light source since Freeman (2011) had stated “for photography, the normal limits between reddish and blue are about 2,000K (flames) to 10,000K (deep blue sky).” Being aware that the lowest preset on my camera was 3200K (Tungsten), without setting the custom white balance to reflect this, I was interested to see whether AWB could handle the situation.

AWB                                Daylight  5200K               Tungsten 3200K
         
All 3 secs F5.6 ISO100 85mm

The AWB and tungsten gave the image a blue hue. The best image was the daylight white balance setting. This is not what I had expected. It seems that the higher temperature setting had warmed up the image. I think the camera had measured something close to tungsten.  I have learnt from this that if I am not sure of what temperature setting to use, I need to take test shots to compare the images before I take the actual image.   The other way round this is to shoot in RAW and alter the colour temperature using the colour temperature slider bar.

The point at which this image started to lose its blue colour cast is at 4400K, and probably looks best at 7400K. After this point, it became slightly brown / green in colour.

7400K

References
Freeman.M, 2011, Digital SLR Handbook, Ilex Press, Lewes, UK p60
Freeman.M, 2011, Digital SLR Handbook, Ilex Press, Lewes, UK p61

Bibliography
Freeman.M, 2011, Digital SLR Handbook, Ilex Press, Lewes, UK
http://www.digitalcameraworld.com/2012/05/23/what-is-color-temperature-free-photography-cheat-sheet/ accessed 16/7/13

Sensor Linear Capture

This exercise simulates the image which is captured when an image is first taken with a digital camera.

Taking an unprocessed jpeg image, I opened it in Photoshop and converted it to 16 bits using the following process:

Image-mode-16 bits

I questioned the difference between 8 and 16 bits because it was a term I have seen when converting from RAW to JPEG but did not understand its significance. Having read around the term, I now understand that 8 bits are made up of less colours than 16 bits. The numbers were a little mind boggling, but basically, in computer language, 8 bits are made up of 2 to the power of 8 equalling 256. When 256 shades of red, 256 shades of green and 256 shades of blue are multiplied together, there are just over 16 million colours available. With 16 bits, the numbers are higher because it is made up of 2 to the power of 16 and when multiplied again, the number results in trillions of colours. The reason for using 16 bits became clear at the end of the exercise. More space is required to save the image as it is larger. Also jpegs only work in 8 bits.

    
Opening curves (Image-adjustment-curves) (ctrl m), I adjusted the curve to make the tonal value darker by shifting the pixels to the left hand side.


This is similar to what my camera sensor sees.

 
To push the image back to where it was, the curve has to be reversed so that it looks like this: (Gamma correction curve). This was more difficult than I expected to get it absolutely right. One small movement of the curve and the tones became darker or lighter depending on where the curve was placed.
 
This is the curve which would take my image back to about where the original image was, and when the new histogram is viewed it is very similar to the original image. The difference was in the saturation of the red. On the final image, the red was slightly darker, although the sky was an exact match.
The image which has been darkened and lightened to show more noise in the shadows and darker areas such as the sea because they have been lightened.

Left: Original        Right: Altered

Looking at both images side by side, more noise is shown in the image which has been darkened and lightened (gamma correction curve). The noise was present before the image was altered, and the processing has exaggerated the effect. The course material explains that this happens because the shadows area has been lightened so strongly. This is similar to the effect that would be created if the image was lightened in photoshop. I had seen this effect during a previous exercise when I increased the ISO to see if I could take an image without using flash. As I brightened a particular part of the photo in photoshop, the noise became visible. I now have more of an understanding of why this happens.

Bibliography
http://www.photoshopessentials.com/essentials/16-bit/ accessed 15/7/13
Gulbins,I Steinmueller,U,(2010) Digital Photography Workflow Handbook, Rocky Nook, Germany (p144)

Assignment 1: Workflow

For this assignment, I decided to develop the theme I started with Exercise 2: Your Own Workflow 2 and Exercise: Editing. I am interested in mountain biking (MTB) and had spent time previously reading MTB specific magazines looking at images, thinking I ought to learn some basic MTB photography skills. With my husband increasing the amount of riding he does preparing for races, and my son just learning, I was keen to adapt my motorbike racing photographic skills and look at this subject area with willing models. Having learnt basic MTB photography skills following a workflow of developing my skills by research, practice, evaluating and more research, I organised a MTB ride with my husband and son with the aim of producing 6-12 images for my assignment. I wanted images which would narrate a story, so I planned an evening using the downhill section at the trail centre.

During this assignment, I looked at creating an effective workflow all the way through from planning to the final 6-12 images. I considered how my workflow may differ from other photographers in this area, and explained why I made some adaptations to my original work flow.  I devised a flow chart to enable my planned session to work fluently from planning to the final displayed image. To make the flowchart more manageable, I broke it down into five separate flowcharts and described my actions for each one.

Flowchart 1: Preparation

 

The first flowchart looked at preparation. Living close to a trail centre in Sherwood Forest meant I was able to utilise the trails on weekdays and evenings when the section was least busy. Having decided what type of images I wanted, I planned a session with the riders to discuss my ideas and available location (fine detail as in type of track, whether jumps were possible and whether there was access for me as a photographer without being injured). The weather forecast was important too, because I did not want the riders becoming cold and wet. I needed the lighting to be as bright as possible because I thought noise was distracting on these types of images. Sunlight through trees or bright sunlight is challenging too, so I decided on early mornings or evenings. I planned the session for a Saturday evening.

I had charged camera batteries in preparation, set my camera to the following basic settings: TV, continuous shooting, AI Servo focussing, ISO200 and shutter speed of 1/125. To enable my camera to work as fast as possible, I could only work in jpeg. The 24-105mm lens was cleaned, checked for dust spots and fitted along with the 10-20mm lens which was placed in the bag. I fitted the flash with new batteries and checked the memory card in use had enough space along with two formatted ones in the bag. I had learnt that a dustbin sac was important piece of kit for preventing stings, splinters and dirt. The final piece of organising was checking my bike was in good working order with tyres pumped, bag, drink and helmet ready. 

 

I think this part of the flowchart worked well for me. With hindsight, I would look at the colour of the clothes the rider is wearing. On this occasion, my husband had a different top on and I had not considered the effect of the colour against a blue sky background. It meant in some instances there was little contrast.

Flowchart 2: Shooting

Knowing my basic setting helped set up my camera quickly. Shooting a few images and reviewing the histogram and display for burnout and highlight clippings in the back of the camera allowed me to check the settings. The speed and direction of the bike had an impact on the camera settings, and the amount of available light meant the ISO setting needed reviewing. Satisfied with the increase in ISO I took more images, reviewed them in camera and moved on to the next section of track. Gulbins et al (2010) suggest that “select settings>shoot>review your preview image and check histogram>adjust settings>shoot…”is part of a basic series of shooting steps which one will often follow.

The downhill section was always going to be the most challenging section for the riders and me, especially as the weather was so hot. There were three sections of track I wanted to cover in this area: a rock garden, fast berms and a jump. I took each section, took a basic set of images to work out positioning and camera settings, reviewed in camera by checking the histogram, and then let the rider loop round a few times. After checking the camera display in detail, we moved on to the next section.  At the end of the downhill section, the riders took a well earned break whilst I checked my images in camera. I had originally considered packing the tablet to review the shots in larger detail, but because the weather was so bright and sunny, it was easier to use my camera. Having reviewed the images, I thought I had enough images to move on to the cool down section. As my son was becoming tired with the heat, I had to revise my last location for a flatter venue.

With the last set of images complete, we headed home. I wrote this section of the flowchart to be as flexible as possible, fitting in with my mine and the riders’ needs. It works for me because it can be looped round as many times as necessary.

Flowchart 3: Browser

Having arrived home, I uploaded the images from my memory card to the computer using my Canon software Zoombrowser. This allowed me to file the images in a folder with the day’s date on it.

 I started with 155 images and needed to choose 6-12 for the final selection for procession, so use the rigorous process I have developed within Zoombrowser to enable me to select images. By creating a delete folder, I was able to move across any outright mistakes (such as no rider or completely out of focus).

By awarding 1 star to any photos for deletion, I could filter all the one star photos and drag across together thus saving time. This removed 31 of my images, so I had 124 still to sort.   

I looked through all the remaining images, (enlarging to 1:1 if necessary) to award 1 star to images which fitted the following criteria: in focus, shows action (movement of bike) or emotion, composition, perspective, lighting, position of legs, facial expression. I filtered these by the star rating to show 65 images.

Out of these 65 images, I used the same process to look more critically, awarding two stars for the better images leaving 27 images.

For me, this flowchart worked well when using jpeg images. I have worked through it a few times since the editing exercise and would not change anything at this stage. I considered deleting the awarded stars in the delete folder, but by the time two and three stars are awarded and filtered, the one stars are not visible. To leave them in saved me time.

Flowchart 4: Processing

 

I created a 3 star folder to drag the 3 star images across into for ease of locating the images in Photoshop. It also allowed me to run a slide show of the final images to double check them before processing.

 

Creation of a sub folder –e.g. 3 stars enables me to find the images for processing easily and open them  all together.

Flowchart 5: Archive  

I looked at each image individually. By opening a duplicate layer and making changes to the image, I was able to change an image without altering the original image. I followed the same flow for each image – create duplicate layer, open in curves to check histogram for shadow and highlight clipping, altering if necessary to give image the impact required, cropping if necessary, sharpening if necessary using unsharp mask and flattening the image.  One of the limitations of my version of zoombrowser is that image numbering does not allow viewing of images in number order when numbers such as 001 are used. I was not aware of this as I tend to call images by a name. I decided for this assignment to call images 001, 002 etc and still leave the original image number for identification. During my last course, I found by leaving the image number on the name, I could find the original easily if I needed to resize the image. Opening the images in Windows Picture Library displayed the images in the order I wished 001, 002 etc.  This too worked well at this level. I aimed to get the images as correct as possible leaving me with little post processing work to do.  

I backed up my final images on my hard drive, uploaded them into my blog as jpegs and inserted them into my Assignment as a jpeg.  What I did not add into my flowchart is that I would copy the final images across into a folder set up for this course to allow easy access when preparing for submission at the end of the course. I did not want to print these images at the moment and so I have not included “print” on my flowchart.



1/125 F4 ISO400 24MM 

1/125 F4 ISO400 65MM

1/125 F4 1SO200 24MM




1/125 F4 ISO100 24MM 

1/125 F4 ISO100 24MM



1/125 F4 ISO400 24MM  

1/180 F5.6 ISO200 15MM  





    1/90 F5.6 ISO200 20MM                   



1/125 F8 ISO100 70MM



1/350 F4 ISO400 60mm



1/250 F4 ISO200 45MM



 1/125 F9.5 ISO 100 24mm

Whilst reading around the subject of workflow, I came across an interview of a young mountain bike photographer, Nicholas Losacco. When asked about his work, he stated that he likes a “shot that’s in context [meaning] a shot that shows where the rider was and where they are going”. Losacco (2013) I empathise with that, and have strived to show some of the trail in my images. This was an area which I had not thought about before I read it, and it led me to experimenting with a different lens (10-20mm) to enable me to show more of the area around the jump. I also had to search out areas of track especially the berms, where camera perspective allowed me to show where the rider had come from.  A lot of mountain bike photography is taken for magazines.

Thinking about how my workflow differs from other photographers led me to consider the work of professional photographers who would be under a time limit to achieve the shots they are asked to take. They would have the skills required and not need a practice session. Kit could well include a strobe light to light the background and flash, and the professional photographer may use a selection of lenses including an F2.8mm lens.  The shooting may include a day’s shooting over more rugged and interesting terrain, although still by bike, and perhaps covering photos for different subjects – e.g. technical riding skills, well ridden classical bike route, bike on test article, portraits of riders. I would expect that initial processing would be similar to my system, although images may be emailed or sent via the web to publishing companies. They may add key words to their images and may send low resolution images in a contact sheet, so an agreement can be reached on which ones to use. Colour optimisation may be achieved before sending to the publishing company.  

Adaptations I made to my existing workflow included reviewing histograms at the shoot and altering my camera settings where possible. I now set up a delete folder which I delete when I have finished the exercise to save space on my computer and have developed a workable system using the star ratings within the browser software. These have helped speed up my workflow and enabled me to check my work with ease. I have read around the subject of including key words at the processing stage and will be trying it out. I will also be writing a list of shortcuts for Photoshop to keep handy when using the software.  

In this assignment I devised a workflow suitable for taking images of MTB riders. It fits my style of photography at this level and will be able to grow with me. For example, in flowchart 1 (preparation), the kit box can be changed along with the personal equipment for what the day may entail. I may find that I need to put more work into the preparation, or require more detailed boxes. I am a list maker, so I see the list becoming longer. Flowchart 2 (shooting) will stay the same I think for the foreseeable future. Flowchart 3 (browser) seems to work well at the moment and will have key words added to it once tried and tested. Flowchart 4 (processing) will change with me. For example, this exercise was done using jpeg images because of the processing speed required by my camera. I do use RAW and will be looking at the RAW browser software the next time I take photos in RAW. I see this flowchart being developed as I learn new skills. Flowchart 5 (archiving) will be added to if I print my images.  I found this assignment useful because I began to see that I already had a developed system in place and there are additions which I can build in to improve my housekeeping and enable me to speed up my workflow.  

References
Gulbins, I Steinmueller, U, (2010) Digital Photography Workflow Handbook, Rocky Nook, p41
http://www.imbikemag.com/issue24/?page=83 accessed 7/7/13

Bibliography
Freeman Michael (2010) Mastering Digital Photography, The Ilex Press, Lewes
Freeman Michael, (2011) The Digital SLR Handbook, The Ilex Press, Lewes
Gulbins, I Steinmueller, U, (2010) Digital Photography Workflow Handbook, Rocky Nook, Germany
http://www.imbikemag.com/issue24/?page=83 accessed 7/7/13 http://www.popphoto.com/how-to/2012/08/tips-pro-shoot-better-mountain-bike-photos accessed 19/6/13 http://www.digitalcameraworld.com/2010/02/12/mountain-biking-photography-tips/ accessed 19/6/2013 http://allphotobuzz.blogspot.co.uk/2010/04/mountain-bike-action-top-tips-for.html

Reflection – assess against course criteria
Demonstration of Technical and Visual Skills – materials, techniques, observational skills, visual awareness, design and compositional skills Set up of camera, use of lenses to create effect I am looking for, observational skills – top against sky (lack of contrast) design – practicing to get desired effect with action shots
Quality of outcome – content, application of knowledge, presentation of work in a coherent manner, discernment, conceptualisation of thoughts, communication of ideas Mix of images, knowledge applied to work flow chart and images, work presented coherently, began with an idea which was developed (see also test shots on blog for development of ideas)
Demonstration of creativity – imagination, experimentation, invention, development of a personal voice Deciding how I wanted an action shot to look and practising, experimenting – reading something, trying it out and evaluating, then re-reading and further practising,
Context – reflection, research, critical thinking (learning log) Reflected, researched and added a couple of references to the work. Looked at work of other photographers.