Zenfolio | Chris Stuart Highland Photography | Image Processing

 

INTRODUCTION

When taking photographs digitally you have two basic choices as to how you want the camera to capture and store your image files and these are:-

  • JPEG
  • RAW
  • DNG (Digital Negative) is a third choice available with some cameras and is an attempt to create a publicly available format as an alternative to the proprietary RAW files of the individual camera manufacturers.

JPEG

The term "JPEG" is an acronym for the Joint Photographic Experts Group which created the standard. It can be a useful file type for eventual storage of certain processed images, especially where you want to keep the file size small, perhaps for emailing or displaying on the internet. However, unless you have no real interest in processing images then I would not recommend initially capturing and storing your images as JPEGs. Essentially a JPEG is an image which has been processed by your camera, not by you. The JPEG image is compressed and will no longer have the full amount of data available and will not allow you to make so many adjustments when processing.

RAW

A RAW file is an image which contains the full amount of data captured by the camera. Note that that different manufacturers have their own RAW formats so you will need to ensure your RAW image processing software will recognise the format you are using. This is not normally a problem. The file has not been compressed or processed and you therefore have the most control as to how your final image looks after processing. The important thing is the image does need to be processed.

 

 

GETTING IT "RIGHT" IN CAMERA vs PROCESSING

There are still many photographers who claim to "get it right" in camera and that they do virtually no processing. The implication is that those who do process images only do so to correct "mistakes" made in camera. I have seen such statements used to suggest that the work of the photographer is somehow "better" or more "pure" than the work of someone who processes their images. I rather suspect this is a throwback to the days of slide film. Prior to slide film, photographers used negative film which had to be processed in a dark (literally) room using chemicals to produce and fix the positive image. It is worth remembering that image processing in the chemical dark room was an art in itself and famous photographers, such as Ansel Adams, spent many hours in the dark room producing their images. This changed with slide film. You generally sent the film away to a laboratory who processed the film for you. In particular you had to get the exposure right in camera as there was no opportunity to recover things if you got it wrong. Slide film allowed little latitude and the tendency was to slightly under-expose, for if highlights were blown the image was ruined. The photographer still had to make decisions regarding composition, lens, shutter speed and aperture. ISO was decided by the choice of film itself. But with slide film there was no opportunity for creative processing by the photographer. The photographer had to get everything "right" in camera.

With digital photography we have a much greater latitude. A RAW file contains the maximum amount of data possible. Post capture the photographer can make a multitude of adjustments when processing the initial RAW image to create the final adjusted image. Bear in mind that a RAW file will have had no adjustments and so will not be sharpened and the colours may not be vibrant, and may not even be correct, depending on white balance settings. The image may appear dull and lifeless and may not truly represent the scene the photographer actually saw. The only setting which has any impact on a RAW file is ISO.

Few if any photographers are content with just taking record shots. We all strive to convey something of the mood and emotion of the scene. So it makes no sense to suggest that processing is somehow "wrong" and undesirable. On the contrary, processing a digital RAW file is absolutely essential to realise the full potential of the image. The adjustments may only be minimal, but they will be essential.

Use of software to process an image will not make a poor image good.

You will still need to make good decisions regarding composition, lens, shutter speed, aperture, ISO etc. A thorough knowledge of the histogram is very useful, especially if you intend to use modern techniques such as exposure blending. Converse to slide film the tendency nowadays is to slightly over expose so the histogram shifts towards the right side as this gives us the maximum amount of data. Having said that, as cameras come equipped with greater dynamic range it is also sometimes more possible to expose for the highlights and bring up the shadow areas in post processing, without the awful "noise" which that would have created in the past.

My view is it is not an either or choice. You need to do both. You need to get things right in camera and you need to process the image. It is important to gain an understanding of processing digital images so you know how best to take the images in the field.

 

PROCESSING SOFTWARE

There are numerous software programs available to process digital images. My own choice is to use Adobe Lightroom to catalogue my images and as a RAW converter to undertake initial minor adjustments, before further adjustment are made in Adobe Photoshop. Although Lightroom is becoming increasingly more powerful I find it does not have the same finesse as Photoshop. I also find it easier to make use of adjustment layers and layer masks in Photoshop. The use of adjustment layers in Photoshop means that adjustments made are non-destructive so do not alter the original RAW file, and can easily be altered later if desired.

 

PROCESSING TECHNIQUES

There are numerous techniques used in the processing of digital images. Some of the most useful and exciting techniques, to my mind, involve the use of luminosity masks as developed by American photographer Tony Kuyper. He has not only documented his experiences in using luminosity masks but has made his findings readily available to others with a set of PDF tutorials available on his website. He has also created a set of Photoshop Actions (TK Actions) which makes creating and using the masks much easier. Another American photographer, Sean Bagshaw, has worked with Tony Kuyper to produce a series of videos specifically to teach the use of luminosity masks. I thoroughly recommend anybody to obtain the TK Actions and Sean Bagshaw's videos to learn how to use them.

The beauty of luminosity masks is that they are based on the luminosity values of the actual image and are self-feathering. They can be used to make targeted adjustments which will only affect a very specific part of the image. Luminosity masks have evolved and nowadays, in 16 bit version, they have become easier to use and at the same time more flexible and more powerful than ever before.

 

 

HDR and EXPOSURE BLENDING

Unfortunately the term HDR has a bad name, primarily as a result of a genre of images produced using HDR software. These images tend to have rather odd colours and are not to everybody's taste.

However HDR simply means high dynamic range, referring to the range of luminosity values within an image. When we look at a scene our eyes are very good at allowing us to see detail even in deep shadows and at the same time we can see reasonable detail even in areas of highlight. The camera is not so good at this so photographers have always strived to find ways to increase dynamic range within an image.

A very common problem is to balance the bright sky with the darker land. Using neutral density graduated filters is a traditional way of tackling this. The filter can darken the sky and balance it better with the exposure for the land. However, with some images, filters can cause additional problems, such as flare, or will darken anything which sticks up into the sky area like mountains or trees. One modern solution is to take several exposures for different parts of the scene and then blend these exposures together in Photoshop to create a final image which is closer to what the human eye saw. This can be done using luminosity masks techniques as mentioned above.

One day we will no doubt have affordable cameras with a very wide dynamic range and such techniques may no longer be required, but this could be many years yet. Meantime balancing dynamic range remains a tricky problem for photographers in some circumstances.