Create Exhibition Quality B&W Pictures

With the release of inkjet printers and special papers and inks, digital photographers can now produce ‘fine art’ prints with a quality that was formerly only achievable through chemical means. But, as with traditional photography, good results can only be obtained with effort and understanding.

Printing the image directly from the camera using PictBridge or a similar facility will rarely give you exhibition quality prints. You need the right shot, effective editing, the right printer and the right media for printing your photograph. In this feature we’ll look at the capture process and investigate the ideal parameters for producing a good B&W print.

Image Requirements
The first parameter to consider is the desired output size for your picture, because it will dictate the image resolution you require. Most exhibition prints are at least A3 size (the larger the print the more impressive it looks). However, to print an image at 297 x 420mm with the standard recommended printing resolution of 300 dots per inch, you need an image file of 3508 x 4960 pixels. The sensor resolution required for such an image is approximately 14 megapixels – which is more than most photographers can afford.

From a practical viewpoint, however, 300dpi may not be essential, as the normal minimum viewing distance for a print is roughly three times its longest dimension. Hence, the closest distance for viewing an A3 print would be 1.26 metres. At that distance, you probably wouldn’t be able to see any difference between an image file printed at 300dpi and the same file printed at 200dpi or even, at a pinch, 150dpi (although softening would probably be apparent at lower resolution settings than that).

If we re-calculate the resolution requirements for a 297 x 420mm print at 200dpi, an image file with 2338 x 3307 pixels (approximately 7.5 megapixels) will suffice. At 150dpi, a 5-megapixel camera will be adequate (although lower-resolution cameras will not). Note: these figures only apply if the image has been captured with the camera’s highest resolution and quality settings – and preferably in the RAW file format.

Shooting in RAW is advantageous for two reasons:

1. In most cases you can convert RAW files into 16-bit per channel TIFF files, which have 256 times more image data than regular 8-bit per channel JPEG files. The more information you have to start with, the greater your ability to adjust image parameters without introducing posterisation and other problems associated with data loss.

2. RAW files can be readily – and very effectively – adjusted in conversion software. This can help you to overcome exposure problems and counteract some of the inherent limitations of digital image files (see below).

Shooting
If your objective is a black and white (B&W) print, is there any advantage in shooting in colour? Opinions vary, but the current consensus is that the more image data you have to start with, the more you can use for printing. This means shooting in colour, even though you want to end up with a B&W print.

Some DSLRs save extractable colour channel data in RAW images when shots are taken in B&W mode – but not in JPEGs. However, most compact digicams with monochrome shooting modes (B&W and/or sepia) discard colour information when the file is saved, which means you cannot access separate image colour channels. This prevents you from using the Channel Mixer strategy outlined below, which produces much more dynamic prints than a simple greyscale conversion. Other conversion methods will be described in our next issue.

If you’re not sure where to position your exposure, then underexpose – especially if you’re shooting JPEGs. Set the exposure compensation at 0.3 stops as a starting point but be prepared to go past one stop if conditions demand. This will reduce the risk of clipping highlights and should allow you to ‘pull in’ highlight detail without losing information in the midtones and shadow areas.

B&W Conversion
There are many ways to convert your coloured original to B&W. Photographers with RAW files should start by selecting a low-contrast conversion setting (if available) to ensure the maximum tonal range is maintained. This will provide more flexibility for subsequent editing and printing. It may also be useful to adjust exposure compensation to bring up highlight detail at this stage as well. We recommend working with 16-bit TIFF images if your editing software supports them; otherwise use the highest JPEG quality setting and be careful with the adjustments you make. Aim to recover as much highlight and shadow detail as you can before proceeding to B&W conversion.
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Digital Image Characteristics
There’s no straightforward way to compare the imaging performance of films and digital camera sensors. The closest analogy we can get is to regard the sensor’s response as similar to that of colour slide film. This means exposure latitude is very limited, so you must expose the shot correctly from the start.

The small sensors used in compact digicams have even less exposure latitude than those in DSLR cameras and it is common for highlight detail to be lost when the camera’s metering system has been set to multi-pattern or centre-weighted mode. Spot metering will allow you to expose to capture detail in the highlights. Bracketing and exposure compensation are useful back-ups to provide you with a usable tonal gamut that includes both highlights and shadows – although you may need to resort to editing ‘trickery’ to have both ends of the range in the same picture. Some of those ‘tricks’ will be explained in this series of articles.

Your Approach
What makes an exhibition quality photograph? Essentially there are two components: the technical aspects that lead to the print and the emotional impact the picture has on the viewer. If you start with a well-composed, correctly-exposed image, edit it appropriately and print it at an appropriate size using a capable printer with high-quality media, the technical aspects will be properly handled.

Creating the emotional aspect has more to do with selection of the subject and the way you ‘tweak’ the image to reflect the impact the subject made on you, which caused you to take the picture in the first place. This impact is what will evoke the emotional response in the viewer.

The examples on this page show how adjustments made in editing software can change the appearance (and, hence, emotional message) of a digital photograph. ‘Darkroom’ work contributes as much to the fine art digital print as it has always done. The image that comes from the camera seldom contains all the elements the photographer ‘saw’ when he/she pressed the shutter release. Transforming it into a compelling picture takes time, effort and an understanding of the tools of digital photography.