Anecdotal Advice for Users of Digital Images

Vista
Microsoft’s Vista uses a unique way of saving image files to allow it to be easily swapped between Vista applications. The problem is it cannot be read by older Microsoft versions or other operating systems so you must save files as JPEG at maximum quality.

The JPEG myth
Jpegs are good but there are many misconceptions surrounding their use, in particular that they degrade quality. Jpeg acts on an image file like a book reviewer summarising a book to make it simpler and smaller. Done once and the full plot and characters will remain but carried out repeatedly will mean small details in the story are left out. Other ‘non-lossy’ formats, such as Photoshop .psd or TIFF .tif are the ones to use if you intend to work on an image over a number of sessions, but when you’re finished and ready to print, then save the final version once as a JPEG. The resulting file will be smaller and much quicker to burn to CD or send via the internet.

RAW Files .nef .raf .kdc .erf .raw etc!
As the computing speed and memory card capacity of cameras have grown, manufacturers now offer RAW files as an alternative to JPEG and TIFF. RAW is the unmodified file information, which has been described as a digital 'negative' - it has the benefit of retaining marginal detail, especially highlight and shadow ones, to be saved on the camera memory card but the files are not 'ready to print'.

By their nature they require further processing by software such as Photoshop, to refine the RAW file, optimise the image and then save it in another format. Whilst we can read RAW files the format does not integrate with our printing equipment and cannot be used directly. Furthermore, a RAW image file may contain extraneous detail and artefacts that might adversely affect the image quality, like an author’s rough draft, with all the crossing out and pencil notes in the margin!

Scanning dpi (or ppi)
The most important ‘number’ regarding a scanned image is the overall file size (expressed as Mb). The next most important detail is the quality of the optical system used to scan. Digital cameras are normally compared in terms of both its Mb size and the lens that comes with it!

The dpi of an image by itself has no bearing on image quality because it represents only part of the story.

Example

An image is 50cm x 40cm at 300 dpi is 79.8 Mb

An image is 208cm x 167cm at 72 dpi is 79.9 Mb

Which is bigger and better? They are the same but just written in a different way. Dpi must always be expressed with the physical dimension because only then can the file size be known.

Scanning should always be done at a dpi setting that is appropriate to the required file size. There can be some benefits to scanning all film at the highest possible resolution but in the end the file size must be suitable for the purpose for which it is needed. Once again, time and storage capacity can make a nonsense of scanning a negative to produce a 200 Mb file if all that is needed is a 7x5 print.

Our own digital print equipment, supplied by the industry leader, Noritsu, decided some time ago to automatically scan film with a resolution appropriate to the end use. One of their engineers then decided it would be a good idea to save the image file at 72 dpi , presumably because it matched the format for a computer’s monitor. We concede this is a nuisance because it means the dimension and dpi files may then need be adjusted to suit other applications. Oh well, if they had chosen 300 dpi then we’d all be happy apart from the people who want 200dpi, or 4000dpi or 248dpi.

Bit size 8-bit versus 16-bit
Increased computer speed has led some software to make use of 16-bit but not all software!

Think of bit size as the size of rucksack: a 8 kilo rucksack can be carried up a hill by most people but a 16 kilo will prove impossible for some. Does the size of your rucksack make you a better person?! Stick to 8-bit please.

RGB not CMYK
RGB is for photographers with a camera.

CMYK is for people who have a machine that needs a forklift to move it and have their ink delivered in 60 gallon drums.

So RGB then, either sRGB or Adobe RGB (1998).

Applemac section

Aperture
The software for coping with huge libraries of digital images. It works happily with RAW 16-bit images and one day the whole world will be using RAW 16-bit… in the meantime please save files for printing as 8-bit JPEG.

Also, as with Apple Cinema Displays, it encourages a tendency in photographers to boost colour saturation to make the whole world appear as though it is made out of play school plastics. Photographic papers are designed to accurately reproduced natural colours in the real world but we can make some compensation at the printing stage if you prefer your colours very rich – please let us know.

Apple Display Users
Lucky users of Apple Cinema HD screens are treated to one of the best graphics displays available: so good that colours appear brighter and more vivid than real life. By comparison normal photographic prints may be appear a bit flat and lifeless but we can compensate for this if you let us know in advance. In the special instructions section just mention Apple Display and we will print appropriately.

iPhoto
is a great application but saves prints in two folders: Original and Modified, which ensures there is always a backup copy of your photograph if you make changes to a photo. If you then Burn a selection of images onto CD through iPhoto it will write both file types and we cannot then be certain which version you’d like printed. The easiest alternative is to ‘drag and drop’ your selection from the Album out of iPhoto and onto your Desktop or another folder. Then use a separate application such as Toast or Nero to write the CD and only your selected files will be saved on the CD. Be sure to send only the images you’d like printed.

 ‘There will always be someone with a different opinion’

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Datasheet

April 2008

The Darkroom UK Ltd

www.the-darkroom.co.uk

01242 239031