Monday, 12 September 2011

Colours into tones in black & white

Exercise - 4 photographs

This is the final exercise before the colour assignment in part 3 of the course and looks at the effect colour filters have on black and white image processing. Coloured filters are a creative tool that photographers have been using for many years with film cameras. These days it's much easier to get the same effect in Photoshop post capture. 

This exercise involves taking a straight forward image containing the colours red, green, yellow, blue and neutral grey. The image is converted to black and white and the effect on each colour is compared when a coloured filter is applied. My understanding is that a coloured filter will let it's own colour light through but block it's complementary colour light. E.g. a red filter will allow red light to pass through and therefore appear very light but will block it's complementary green light which will therefore appear very dark in a monochrome image. The strength of the colour filter will also have an effect on the image e.g. a yellow filter will have a stronger effect than a light yellow filter.

My only previous experience of using this technique is when taking landscape images in black and white and applying a red filter effect post capture in Photoshop to darken the sky as in the image below.

Tay Road Bridge Footpath
Filters can also be used in portrait photography to adjust skin tones.

These first two images show the before and after in a straight forward conversion to black and white with no colour filters applied.

These next two images have a yellow and blue filter applied respectively.


Yellow Filter
  • allows yellow light to pass through so it appears very light in tone
  • blocks blue light so it appears a much darker tone
Looking at the results above it would also appear to allow some red light to pass through as this is also lighter than the default image and has a slight darkening effect on green light.

According to the course notes a coloured filter will lighten any object of the same colour and darken the tone of the others. However the image using the yellow filter definitely shows the red object lighter than the default image.

Blue Filter
  • allows blue light to pass through lightening the tone
  • blocks yellow light so it appears much darker in tone
 In the image above the blue filter has little effect on the green area but the red area also appears darker.

The next two images show the effect of the green and red filters respectively.

 Green Filter
  • allows green light to pass through lightening the area
  • blocks red light making it appear darker
Surprisingly the most noticeable and strongest effect on this image appears to be with the yellow when it should be with the red. The yellow is much lighter than the red. The green area appears only slightly lighter than the default image.

Red Filter
  • lightens red in tone
  • blocks green light making it appear darker
Both the blue and yellow areas have also been quite strongly affected in this case.

As the results are not as I anticipated or suggested by the course notes I'm wondering if the initial default conversion in Photoshop has applied some changes in the colour range that have altered the expected outcome. There is no doubt the the original colours are red, green, yellow and blue. My understanding is that the only area that should have remained unchanged throughout the series is the mid grey colour which is unaffected by the coloured filters and that all the other colour changes are predictable.

Regardless of the results here I now have a better understanding of the effects created by the use of coloured filters and how they can be used in black and white photography. They are a useful tool that can be used to suppress or highlight areas of an image when converting to monochrome.

Wednesday, 7 September 2011

Colour Relationships. Part 2

Exercise - 3 or 4 photographs

For this exercise I have to produce 3 or 4 images with colour combinations that appeal to me and don't necessarily follow the rules of colour relationships.

This first image was taken at the Railway Museum in York and is an abstract shot showing the reflection of a car on an old railway engine.

Red and yellow when combined in an image are contrasting and create an element of tension. In this case the red is not a pure hue but more a deep, dense burgundy colour. Likewise the yellow is not a brilliant, bright yellow but slightly darker. The proportion of each colour within the image helps this combination work.

The relative brightness of the yellow reflection, although occupying a smaller area, draws your eye and brings the reflection to the foreground. Whereas the deeper, heavier red acts as a solid background.

This second image to me just says summer. The bright sunshine makes the image feel warm even though the colours are essentially cool. The fresh green leaves and peaceful garden bench in the shade suggest a quiet place to rest on a hot summers day.

St Andrews Botanical Gardens
In contrast to the first image, I like how this image makes me feel rather than just the colours for their own sake.

The Gyles - Pittenweem, Fife

According to Von Goethe's theory on colour values blue has a value of 4 and orange a value of 8 therefore in order for the image above to be harmonious there should be twice the area of blue to orange to balance the scene. This isn't the case but the addition of the neural fawn area of stonework breaks up the two areas of orange which reduces their overall intensity and the green accents help to direct the viewers gaze away from the blocks of colour and create a pleasing image.









Colour Relationships - Part 1

Exercise - 3 photographs

A complementary colour is one which is directly opposite the other in the RYB colour wheel.


The theory of colour continues with each colour being assigned a value dependant on it's relative brightness. This theory was first suggested by Johann Wolfgang Von Goethe, a theoretical physicist and writer, in 1810 when he assigned the following values to colours.
  • yellow 9
  • orange 8
  • red 6
  • green 6
  • blue 4
  • violet 3
 In order to combine colour harmoniously within an image the ratio of each colour should adhere to these values.

This exercise is to produce one photograph for each combination of primary and secondary colours as close as possible to the proportions suggested by J.W. Von Goethe. So the 3 images should be:
  • Red/Green 1:1 - red and green have equal values
  • Orange/Blue 1:2 - orange is twice as bright as blue
  • Yellow/Violet 1:3 -  yellow is three times as bright as violet
Red/Green


Field of poppies
The image above demonstrates the use of a red/green colour combination in a balanced ratio. It would be easy for the red to overpower the green in this image as the green has a more subtle, less bright hue. The fact that the red is scattered intermittently throughout the image helps to balance the interaction between the two.

Orange/Blue

Aperture Priority f/11, 1/4sec at ISO100
 This image has orange and blue in combination and is framed and cropped quite radically to a more abstract image. The lighting has created shadows and areas of increased/decreased saturation. Despite the crop the area of blue is proportionally still too large to meet the correct ratio. I feel this image is more blue with an orange accent.

This image below is more in proportion.

Taken at f/11, 1/250sec, ISO100

Yellow/Violet

This has been the hardest colour combination for me to capture. I can't think of too many everyday areas where I have seen this colour combination except for in flowers, the most obvious being pansies or violas.
I took this image of a violet clematis flower in the garden.

Initially I tried to compose the image in camera to the required ratio by moving in closer or changing focal length etc but was unable to produce an image that met the brief. I then resorted to post processing in Photoshop to crop the image to the suggested proportions.


 This has resulted in quite a severe crop and a more abstract image which, although it applies the "rules" of colour relationships, is not very interesting. My feeling is that if you hadn't seen the original image before it was cropped you might struggle to recognise the subject. 

Whilst I've been working on this exercise I have realised that some colour combinations are much easier to find than others and that I tend to work instinctively when combining colours. The resulting images don't always conform to the rules here. Sometimes they work and make a great picture and sometimes they don't.