Techniques

We’ve enlarged on some of the most frequently used technical terms from our website to assist you. Feel free to contact us if you’d like more information.

Black and White Lambda prints

Also known as Digital Bromides, black and white Lambda prints have been developed for the art market by Harman in collaboration with Metro. By adapting a large paper processor in conjunction with the manufacturers, Metro’s innovation lead the way for the possibility of producing large resin and fibre-based black and white prints on a Lambda printer. Harman adapted their FB paper for the Lambda and Metro are the sole UK lab to offer this service and one of only a handful of places in the world that is able to produce these beautiful fibre-based prints using Ilford Galerie FB paper. To see how our customers have been making use of this innovative technology, see Our Work.

Canvas printing

We print directly onto high quality real fibre artist cotton canvas. We achieve high quality vibrant canvas prints from your images by using a six-colour UV true pigment ink system, on our Epson 9880 which provides long-lasting lightfast canvas prints.
Sizes available are 10x8 to 44x33 inches stock but we can produce longer if required.

CCD scanning

We have two scanners – the Durst Sigma CCD scanner for film up to 5x4 and the top of the range Creo IQ Smart 3 which is a flatbed 16bit scanner with up to 10000 dpi interpolated resolution. Modern scanners typically use a charge-coupled device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. While drum scanners are capable of scanning both reflective and transmissive artwork, a good-quality flatbed scanner can produce excellent scans from reflective artwork. As a result, drum scanners are rarely used to scan prints now that high quality inexpensive flatbed scanners are readily available.

Clip test

A test to see if a roll of film has been exposed correctly after processing. A technician will cut a short length of film from the end of your roll, and then process it for you to check and balance.

CMYK conversion

Conversion of an RGB file used to display on a monitor or print photographically to a CMYK print space used in the litho printing industry.

Contact print

Negatives are printed directly to paper. A quick way to see the results of your film without printing up individual negatives. The contact print will show positive images at the same size as your negatives.

Colour management

The term ‘colour management’ simply refers to controlled conversions between the colour representations of devices such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses and other corresponding media. For more information see our Colour Management area.

Dip and dunk processing

A method of machine processing where the film is dipped into a series of deep chemical tanks, rather than pulling the film through a roller machine. Dip and dunk virtually eliminates any risk of scratching film during processing.

Drum scanning

Drum scanners continue to be the tool of choice for high-end film applications. Because film can be wet-mounted to the scanner drum and because of the exceptional sensitivity of the PMTs, drum scanners are capable of capturing very subtle details in film originals. Your original film or photograph is mounted onto an acrylic cylinder, which rotates at high speed passing your image in front of precision optics. We can scan any size of flexible media up to 24x20 inches. Film is mounted in an oil bath enclosed in an acetate sleeve which eliminates most surface marks or scratching. Scans are produced at 609 dpi. Drum scanners produce exceptionally smooth tonal gradients and a high level of shadow detail. They are particularly suitable for large scale enlargements. For more information about scanning, please click here.

Edition Prints

Edition prints are reproductions, often in a limited number, of an original. When editions of photographs were produced from film, typically the Edition would be produced at the same time, proving to be a costly investment on the part of artist or gallery. These days Edition prints produced from an archived digital file can be produced at any time due to the stability and uniformity of the digital printing process. This makes Edition printing an affordable option even at very large sizes. At Metro we offer a free of charge Limited Edition service for several specialist printing services. This service takes the anxiety and hassle out of managing Limited Editions and proving their provenance.

Encapsulation

Your photo is enclosed in a matt or gloss sealing film containing a UV filter in a hot vacuum press, so your images are protected from fading in both artificial light and sunlight. Once encapsulated, the surface of your image can be cleaned with a damp cloth.

Epson GMG proofs

A CMYK contract proof printed to the Fogra 39 international print target

Giclée printing

The word Giclée (“g-clay”), is derived from the French verb gicler meaning "to squirt or spray", Giclée, is used to describe a fine art digital printing process combining pigment based inks with high quality archival quality paper to achieve an inkjet print of superior archival quality, light fastness and stability. Our prints are created using an Epson 9880 with Epson Ultrachrome K3 inks, which with the 8 channel print head is capable of producing an extremely wide tonal range and colour gamut.
Giclée printing offers both a softness and richness of colour and our operators will ensure the print represents the artist’s original work in the closest possible way by working with the client and producing a test print as part of the service.
The process involves squirting or spraying microscopic dots of pigment-based ink onto high quality art paper or canvas. The image is colour corrected to attain the closest possible match to the original work if required. The digital information is fine tuned to the type of paper or surface on which the image is to be printed, further ensuring fidelity to the original.
Giclées are printed on a variety of substrates or mediums, the most common being watercolour paper or canvas. Image permanence is a concern to artists and collectors. Estimates are based on laboratory simulations of aging to give a fade &colour shift resistance of up to 200 years in ideal conditions, tests developed and conducted by Epson.
Reproducing prints this way can be of an advantage to artists who find it unfeasible to mass-produce their work, but need to reproduce their work on demand. Once we make the master print and archive the digital master file, we can produce identical edition prints at any point in the future.

Epson 9880 printer

This pro quality digital printer allows us to print large format photos up to 44 inches wide with the finest quality results. We can use papers of up to 1.5mm thick with this machine. Ideal for fine art photography and proofing.

Visit Epson’s website to read more

Hand printing

A master printer will produce the finest traditional print from your photographic negative. Hand prints are made in an enlarger, which holds your negative for light to be projected through onto your choice of light-sensitive photographic paper. The printer will make several tests initially before making your final print. They may use techniques like cropping, burning and dodging to frame your image correctly and get detail into the highlights and shadows. Once the paper has been exposed, prints are hand processed in photographic chemicals, then washed and toned to archival standards.

Index print

Created by digital scanning on a mini lab, an index print is a 6x4 inch print of small images of every shot on a roll of film. They’re useful for storage, indexing and reprinting reference.

Lambda printing

The Durst Lambda is a continuous roll to roll single beam, 3-laser (RGB) exposure system giving total size flexibility and achieves an image quality which is superior to all large for-mat printers - photographic, inkjet and electrostatic. The Durst Lambda exposes digital information (raster pixel) directly to conventional photographic media at full continuous tone with a linear writing speed of up to 65 cm (26 in.) per minute with the choice of two resolutions of 200 and 400 ppi (equal to an apparent resolution of 4000 dpi). The Lambda produces images with the highest possible resolution (68 billion colours) and with a radiometric repeatability of 0.025 D per colour.
Prints can be produced to an infinite length and when the 50 inch paper width is exceeded, images are automatically divided-up and exposed in strips.

Visit Durst's website

Lightjet printing

The Oce Lightjet 500XL is the only photographic printer in the world which can print to 10ft x 6ft in one section.

Lightjet images onto an internal 270 degree drum architecture which holds the media stationary while imaging. The media is held flat against the inside of the cylinder wall. Laser light, which exposes the media, is reflected by a spinning mirror moving along the axis of the cylinder onto the surface of the media.

On the Fly hardware scales images using 16 point bicubic interpolation. Uniform spot size and shape ensures that even the edges and corners of an image are as razor sharp as the center. This uniformity is better than any obtained from the best optical printing techniques. This technology results in better image sharpness, uniform density and colour and the highest geometric accuracy over the entire imaging surface.

Pre-flash printing

Exposing the paper briefly to a white light to sensitize it before the main exposure of the negative. This gives better separation in the shadows and improves highlight detail.

Provenance certificates

Proving the provenance of a photographic print for collectors has been an issue for our customers for some years. To respond to this need, we have created specially designed Limited Edition printing service, designed to ensure that a track record is kept of all the edition prints from a series and proper certification of each print can authenticate Edition prints.. Each certificate features details about the image printed, the series from which it was produced, the paper type and date of production. One of these certificates will accompany each of your Edition prints. For all Lambda Premier and Black and White Lambda services we can offer this service free of charge.

Push processing

Over-developing film at the processing stage in order to compensate for underexposed film. Some photographers use this technique deliberately to squeeze a bit more speed out of a slower film in low light. Side effects are the increase in contrast and graininess of the film and loss of detail in shadow. This technique is mainly used with black and white and E6 films, as C41 film does not push / pull process well.

Pull processing

Under-developing film at the processing stage in order to compensate for overexposed film. Side effects are a decrease in contrast, but it’s a useful technique for rescuing accidental mistakes. This technique is mainly used with black and white and E6 films, as C41 film does not push / pull process well.

RAW conversion

Rather than your camera’s small computer saving your pictures to a JPEG or TIFF format with specific colour and contrast settings, the RAW format saves all the raw sensor data as a file to convert into a working file space. The benefits of this method include better quality; no loss of data to sharpening or compression and, by archiving your images as raw files you can reprocess your images as image processing software improves.

Sealing

Prints are covered with a matt or gloss sealing film in a hot vacuum press. This gives depth of colour and the surface can be cleaned with a damp cloth without any problem. In terms of care and display, heat sealed items are ok to display under strong levels of light, but exposure for any great length of time should be avoided. Also worth noting that blacks in your image will be flattened slightly by a matt seal.

Soft and hard proofs

Soft proofing is a means of previewing on your monitor how your image may change when it is printed on paper as a hard proof. You can toggle between your file and the softproof file to see how colours have changed as a result of the restrictions of the printer’s capabilities. This then enables you to make the necessary changes to get the best from your printer and your file. For more information about installing and viewing a softproof, click here. In all our specialist printing services this proofing is undertaken by our printing team. If you are using Kiosk or Online printing services, however, this information may be useful to you, along with general Colour Management info found here. (Please note: if you do not follow proper Colour Management guidelines, soft-proofing may be unreliable and Metro cannot accept any responsibility for Online or Kiosk prints that have not been properly colour-managed by customers.)

Thumbnail

A small preview of a larger image to help you organise your images. On your computer you can scan through a set of thumbnails more easily and quickly than opening the same set of large image files.

Window mounting

A bevel-edged window is cut in acid-free archival board and the print mounted behind to set it back slightly for framing. This is the only type of mounting for photography that is considered totally archival due to the reversibility of the technique.