Technical Issues and Considerations

 

Sections:

  1. RAW Format - What it is and why we NEVER shoot JPEG!
  2. The Science of Black and White Conversion

1. RAW Format – What it is and why we NEVER shoot JPEG!
(modified from an industry article written by us)

No genuinely professional photographer would ever shoot JPEGs in camera, and this, in our view, is one of the first things that a prospective client should ensure of their photographer.

So, what are RAW files, and why are they so much better than JPEGs?

Firstly, RAW files are professional digital files captured in 16-bit format, JPEGs are only 8-bit. That’s 65,536 values per channel (steps in colour, if you like) for RAW versus a paltry 256 for JPEG. The difference is in the accuracy as much as the range. At the end stage, the file needs to be converted down to 8-bit to print, but if capture and editing are in the biggest space available, with the most information, the detail, accuracy and quality is very significantly greater. This is particularly important when needing to edit an image for custom printing (as they always should be for best results!). The larger file gives way more information and double the pixels to be able to manipulate before cracks appear in the image. Post-production is (or should be!) done in 16-bit format, not 8-bit … for this reason. If you only capture in 8-bit, you are throwing most of the information away before you even start (over 281 trillion colours!).

Secondly, RAW is not a processed format, whereas JPEG is. A RAW file is just the raw light information captured by the sensor, with no assumptions or data changes made by the camera. When you shoot JPEG, by contrast, the camera

  • decides what is black and what is white (in terms of range of exposure) and clips all the bits in the scene that fall outside of that – never to be recovered. Bright areas of clothing, sky and clouds and even skin tones are permanently lost and cannot be “fixed” in Photoshop
  • guesses what the colour temperature is in the scene – i.e. white balance. (When you shoot inside at night using the room lighting, you will notice that everything unflashed looks brown/yellow – because the camera does not know what “white” is. You can change this in Photoshop afterwards, but it massively degrades the quality of the file, especially in low light situations. Not so with RAW, which also enables colour to be corrected in all areas of an image that has mixed colour temperatures.)
  • sharpens the file (how, how much, for what exact print output size, and why?) and then
  • compresses it into a JPEG, which is a lossy format. In the very saving of the file, it throws away information that you can never recover. Then, every time you open and resave a JPEG, you are throwing even more information away. Same story when you edit a file, worse in 8-bit!

A RAW file cannot be changed – it can only have adjustments floated over it that do not degrade the file itself. It also has a far larger dynamic range (information content). So you can change critical colour temperatures, tone curves, contrast, exposure, hue and saturation and many more things in a lossless environment AND in 16-bit format, before you even start the editing itself – still in 16-bit. You can multi-composite different versions of the same file (separate outputs for shadow detail, highlight detail, midtones, etc.) for a huge and highly detailed image that captures information from black to white and across any number of different colour temperatures, all looking correct and balanced. You sure can’t do that with a JPEG!

The most common excuse used by photographers for not shooting RAW is “I don’t need to because I get everything exactly right when I shoot in the first place”. That might potentially be true if shooting in a white studio under perfectly controlled lighting conditions, metering absolutely everything (exposure and colour temperature) and with no post-production required at all. However, when shooting outside, on location, and in any situation where the lighting cannot be controlled or changed, this is an indefensible excuse. By their very nature, weddings (for example) involve extremes of light outside the range of 8-bit capture (black suits, white dresses, bright sun and dark shade, all changing with every shot taken) as well as mixed and changing colour temperatures (inside during the day, as well as under tungsten, fluoro and mixed lighting; outside in the open, in the shade and at night). Location based commercial photography is the same. This sort of photography is not studio work!

A good question to ask a photographer who chooses not to shoot RAW would be “do you just use the automatic / program / green setting on your cameras, or do you use settings that allow you to determine the exposure for each image (aperture priority, exposure compensation, manual, etc.)?” Of course, if they just use the automatic setting, you wouldn’t take them seriously as a professional. If, inevitably, they say “of course I want to be able to control what I take, so I would never use ‘program’ “, you would then ask them again why they would allow the camera to make all the processing decisions as soon as they have then pressed the shutter button? ... it’s exactly the same thing. You either let the computer in the camera determine all these things (and if it gets them wrong, you either can’t change them (e.g. clipped exposures), or pay a heavy price with image quality if you can (e.g. colour temperature) ... OR you retain the control yourself. Professional cameras (and now many non-professional ones too) are designed to shoot RAW format for a reason. It’s up to the user to decide if they want to use the function for the extra quality and control (which has a cost in additional post-production time), or use the simple “do-it-all-for-me” options.

Our view is that if you are going to a professional photographer, you would expect and want that professional to use professional equipment and all the control that such gear offers – not take the lazy way out to save time (and even try to justify why by claiming there’s no difference in quality anyway). If there were no difference ... the manufacturers wouldn’t bother developing the technology in the first place, and the qualified professionals and, increasingly, keen amateurs wouldn’t use it ...!

This is a complicated but important technical issue that goes to the very core of photographic quality. We will not compromise the quality of work we produce for our clients merely to save our time and effort.
 

2. The Science of Black and White Conversion
(and why this is a task for the photographer, not the minilab!)

With the advent of digital technologies, there is arguably no longer a reason to shoot in black and white (other than with traditional film for purist purposes!). With digital capture, even images that are intended for black and white output should be shot in a colour colour space. Black and white capture discards two of the three colour channels (red, green and blue) and with them almost all prospect of a quality result.

Converting the colour image to a black and white one, however, is not as simple as one might expect. Like all things in Photoshop, there are any number of ways to achieve a result, but many of these will not deliver a good result in the vast majority of cases. To achieve a quality black and white image – irrespective of the method used – requires a good understanding of the science of colour and tonal mapping and will involve  sophisticated techniques as well as many steps to create an outstanding final result.

Two commonly used methods are desaturation and conversion to grayscale. Most importantly, these are the methods used in high-street minilabs. The following example will show why the results of minilab black and white conversions are generally not of a good or predictable quality.

The following picture shows three dramatically different colours on a grey background. Clearly if this was to be converted into a black and white image we would want - and expect - to see nice differentiation between all elements of the picture.

Click on the buttons to see the results of “desaturation” and “conversion to grayscale” on this image:

Colour Wheel
DesaturateConvert to Grey ScaleShow Original

As you will see, desaturation converts all three colours to an identical light grey, and conversion to greyscale renders yellow and green the same tone and red slightly darker. Both results are entirely different, and neither seems “logical”. Both methods are, in practice, uncertain and unreliable and lead to black and white images of very poor quality.

Black and white conversion from a colour original requires experience and expertise, and for quality results should not be left to a lab. As specialists in crafting beautiful black and white images, we encourage clients to engage with us where these are sought.

 

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