Noise is considered an error. Post-production software corrects it out of the box. But using it for aesthetic purposes, as we do with grainy silver film, expands the creative range of our photographs.
The original 2592 x 3872 pixel file is cropped to 1132 x 1711 pixels. It already contains a lot of noise due to the old generation 10 MP CCD sensor and the high sensitivity selected (Nikon D200, ISO 1600). After this extensive cropping, if you want to make an A4 print, you have to resample it in Photoshop. Noise is added before printing to give a clean grain.
From silver grain to digital noise
A photograph without the slightest visible grain has been a common obsession since Daguerre. In his book La Photo, published by Denoël in 1976, Jeanloup Sieff described Kodachrome film as “formidable, extraordinary, brilliant (…). No grain, incredible resolution and heavenly colours. But it’s only 25 ASA”. He goes on to talk about the pointillism of the painter Georges Seurat and suggests the use of Ansco 500 (also known as GAF Anscochrome 500 in the 1970s), a very grainy slide film. With our digital sensors, the problems are similar but on a different scale. Digital noise is due to the amplification of the signal by electronic image processing. It appears as you increase the ISO. Cameras with older sensors generate more noise, especially CCDs. At ISO 100, noise is almost invisible. The higher the sensitivity, the more it appears.
By default, the software that processes raw files applies noise reduction, even if only to correct colour or chromatic noise. But this noise, reminiscent of the grain of high-sensitivity silver-halide film, can be accepted or even desired for aesthetic reasons. In black and white, the examples are legion: Ralph Gibson, René Groebli, William Klein, Daido Moriyama, Sebastião Salgado, etc. The grain dramatises the image or, on the contrary, plunges us into a dreamlike world: Sheila Metzner and Sarah Moon used it in this way. The colourful Cacharel campaigns of the 1980s added a touch of nostalgia, reminiscent of the Lumière brothers’ Autochrome plates. So let’s dare to be grainy and noisy with our digital cameras.
Crop to make noise more visible
To make noise more visible, you can take inspiration from film photography: don’t be afraid to crop, as André Kertész or William Klein did in the past. In our example, we started by cropping an image of a trapeze artist in full flight. The blur adds movement to the image. The crop from the original 10MP file (2592 x 3872 pixels) is reduced to 1132 x 1711 pixels. Displayed at 100% on a 27-inch screen with 2560 x 1440 pixels, the pleasant noise is clearly visible. But will it be visible in the same way on a printed page, a website or a social network viewed on a smartphone? Let’s take the example of the Retina display on an Apple MacBook Pro or MacBook Air, which has a 13-inch screen with 2560×1600 pixels and a resolution of 227 pixels per inch (ppi). An image viewed at 100% will give a fairly good idea of the noise that will be reproduced on a print, but it will be much less than that perceived on the 27-inch screen with 2560 x 1440 pixels and a resolution of 108 ppi. Noise or other forms of grain will be added depending on the final medium and the size of the image on that medium.
Some areas of the image may have defects, such as a loss of detail due to local overexposure. If these defects are small, they will not affect the picture. However, if they are sharply cropped, they can become distracting. By cropping the image sharply, the left part of the trapeze artist’s suit, which is overexposed and lacks detail that can be restored, takes up too much space. It needs to be retouched.
Noise does not appear the same on a print as it does on a screen. It depends on the size of the print and the resolution of the image. Our cropped image is 1711 x 1132 pixels, or 14.49 x 9.58 cm at a resolution of 300 ppi. But we want to make a print that is 28 cm long. So we need to resample the image. The print will be made on an Epson SC-P800 printer. Its native resolution is 360 dpi. In other words, the driver interpolates all files it receives at 360 ppi. By resampling the image to this value, the driver does not change its resolution. The image will therefore be 3969 x 2626 pixels, giving a size of 28 x 18.52 cm at 360 ppi. The Preserve Details 2.0 resampling algorithm is the most efficient for increasing image size. However, when you increase the image size, the noise is diluted a little. We will therefore add some noise after resampling at 360 ppi, so that its structure remains intact.
The image is resampled in Photoshop.
Add noise for printing
After resampling the retouched image in Photoshop, noise can be added in Lightroom. In Lightroom we use the Grain effect with the following parameters: Amount 50, Size 50, Roughness 50. It can be evaluated on the screen with an image size close to that of the print. However, it is often necessary to adjust it to refine the final rendering. The perception of an image on screen is different from its representation on a print. Apart from Lightroom, grain can be added in Photoshop (Filter>Noise>Add Noise) or using plug-ins such as DXO FilmPack or Nik Collection, which simulates film in both black and white and colour. But there is still a big difference between noise and film grain: in a digital image, there is little noise in the highlights compared to the shadows and midtones. On the other hand, with grainy film, the resolution of the emulsion is average or even low, and the details are lost in the grain of the emulsion. When noise is added to a digital image, it often looks artificial when applied to an image with excessively sharp contours. In this latter case, it is better to reduce the sharpness of the image very slightly and then apply the noise.
Discover the photography courses at Spéos
Spéos offers various training courses ranging from simple one-week photography courses (initiation and advanced level) to 3-year courses. The long courses to become professional photographers allow you not only to master all the photographic techniques and its vocabulary (blurs, hyperfocus, sharpness zone, depth of field, backlighting, focal length, shutter release, autofocus, wide-angle, rule of thirds, etc.), but also all the stages of shooting and image processing.
Visiting the school allows you to discover the premises, the studios and the equipment, and is undoubtedly the best way to familiarize yourself with your future way of working. This is why, in addition to the open days, Spéos offers throughout the year personalized visits by appointment to come and discover the school with a member of the team.
Text and photos: Philippe Bachelier, teacher of Printing techniques at Spéos