Thursday, December 14, 2006

The Secrets That Lead To Great Colour Photo Prints

The Secrets That Lead To Great Colour Photo Prints
by: Erik Vlietinck

You've carefully composed that shot. You sat there, waiting hours on end to get the colours of that beautiful sunset just right. Then, finally, you shot your great sunset. Everything seemed like OK, but when you print your beautiful photo, it comes out dull, with little of the vibrance you expected to see. What a disappointment!

Most disappointments with photography being output on an inkjet photo printer have to do with the colour workflow. If your colour workflow is not set up well, you're bound to get results that look nowhere near what you expected from the shot in the first place.

So, how should you proceed to get the best looking output on an inkjet photo printer? It all starts with setting up your workflow correctly, and to do that, you need to make up your mind about a few things first. The first issue is to determine which level of output quality you want. If all you want is to output decent looking photographs without much afterthought — more or less like you've shot them — then let the printer decide the colours for you.

Most inkjet photo printers will allow you to either hook up a camera directly through PictBridge or a USB connection. You can then download the images into the printer and have them output immediately. Most driver software will allow you to select the printer as the decision maker for the colours it will print. But if you're passing through the PC or Mac, you should have an idea of how to set up a proper colour workflow.

The Colour Workflow

When printing an image through the printer driver on your PC or Mac, you should open the photograph in an image-editing program like Photoshop, Photoshop Elements, or any other image-editing application. If you shot the photo using a digital camera, and you have used JPEG or TIFF as output file format, the camera will have 'tagged' the photo with a colour profile. This colour profile will be sRGB in almost every case.

A colour profile describes the colour space — the number of colours and which colours exactly — a device can produce or recognize. A working colour space is described by an abstract profile, which serves to give you a device-independent space to edit images in.

sRGB has seen excessively wide use, as especially HP and Microsoft were promoting it as the standard RGB profile. sRGB as a colour space has serious weaknesses — there are a lot of colours today's printing presses as well as other output devices like photo printers, large format printers and many inkjets (not to speak of up to date monitors or digital cameras) can produce that cannot be stored in sRGB. If quality is important, sRGB is not an option.

Nevertheless, you should always use the correct source profile for the data at hand, and only if absolutely necessary convert from that colour space into a better one like Kodak ProPhoto, a colour space that is far larger than sRGB. ProPhoto's ICC colour profile is delivered with most Adobe applications. In your colour workflow your first choice should be to honour your camera's setting and keep the profile attached to the file.

If an application asks you if it's OK to throw the profile away, click 'Cancel', and shout "NO!" very loudly. If you do throw it away, some information about the image's colour gets lost. We can make that up by attaching another colour space's profile but you always risk to throw away a tiny amount of data due to the rounding errors inside the image-editing application's calculation engine.

If you shoot in Camera RAW mode, you're basically taking a picture without any interference of software algorithms at all. The camera will save the image exactly as it 'sees' it. Camera RAW is a format that you can only deal with on a PC or a Mac by using either the camera manufacturer's dedicated software or an application like Adobe Camera RAW in Adobe Bridge or Photoshop CS2, DxO, or another specialised application for editing RAW files.

With Camera RAW you can in theory attach any colour profile as you see fit, but in reality you will want to choose a working colour space that is large enough to encompass all possible colours the camera could detect.

Such a colour space could be the Kodak ProPhoto space and its associated profile. For Camera RAW photos and JPEGs which have no associated colour profile (anymore), Kodak ProPhoto makes the most sense. The colour gamut (number of colours it supports) is larger than AdobeRGB.

So, now you've tagged your photo with a colour profile. You're busy editing it in Photoshop or your favourite image editing application. And now you're almost ready to print it on your brand new n-colour inkjet photo printer. But first you want to check how the colours will look when they've been printed.

Softproofing

In Photoshop and some other image-editing applications, you can see how results will look by checking the image on-screen. To make sure that what you see on screen will be close to what will be on the paper, the monitor should be calibrated and profiled.

If your monitor has been set up properly, you can select the soft proofing feature from your application. Immediately, you will see the colours turn darker, more dull, less vibrant. That is because paper displays colours differently from a monitor (that emits light instead of absorbing it — there it is, now you know). If your monitor is well profiled and calibrated, what you see when softproofing will be close to what your printer will deliver.

The profile used for the softproofing process will be the paper colour profile for the paper on which you intend to print.

Finally, when you're ready to print the photograph, you will select that same paper profile in the printer driver for output. The colour profile that you select in the printer driver will describe which colours the printer/paper combination can output and will translate those colours that it can't but nevertheless are in your image to colours it can.

For photographs you will select a Perceptual Rendering Intent — think of this as the method by which colours are translated in such a way that they match the originals the most visually.

Why Translating?

The question that a layman will ask is why you should translate colours in the first place. The answer to that is: "Due to the differences between devices when it comes colour capabilities".

An inkjet photo printer may be capable of printing many colours, but it will always be more limited in that capability than a digital camera. This is due to limitations in the technologies used in both types of devices. Even the best printer will not be capable to print all the colours a digital camera can represent. (The same can be said of a monitor, by the way).

In order to somehow output those colours on paper as well, the original colours that lie outside the printer's 'colour gamut' are brought inside that gamut using an appropriate calculation method. The Perceptual Rendering Intent is most appropriate to photos because it will shift all the colours in such a way that the overall visual appearance still looks 'right'.

The reason why you should keep a profile attached to an image, or attach a nice, large working colour space profile to RAW images is that you want to be sure that no colours are thrown away from the start. As such a colour profile describes all the colours the image may contain, it pays off to choose a large gamut. That way you're always sure that your image colours will lie inside the gamut.

There are many different ways to come to these translations, and each will have its own slightly different result. That is the domain of colour management.

Where Do You Find Colour Profiles?

Each inkjet manufacturer delivers its own colour profiles for each of its printers with the printer you're buying. However, there may be problems with some of those profiles. Some manufacturers regard profile creation as an afterthought, while all manufacturers will deliver profiles that represent an average of the printers they make.

Unfortunately, every printer is slightly different from the next. Manufacturers will also provide you with printer profiles for all of the papers they make themselves. Again, the manufacturing process is not perfect and differences between batches of paper will exist. And papers that were not manufactured by the printer vendor come without profiles altogether.

While paper mills will create their own profiles, these may not have been created with your printer — most likely they have not.

The only way to get perfect or near-perfect results therefore, is to create your own profiles. You can do so by buying a X-Rite or GretagMacbeth spectrophotometer like the Pulse or Eye-One Pro. These are excellent-quality measurement devices that come with the necessary software. The disadvantage of these packages is obviously the price. You won't get such a device below 1,000.00 Euros, which makes them too expensive for amateur usage.

The one product that is inexpensive enough to be reasonable for any amateur photographer, is ColorVision PrintFIX Pro. Unfortunately, this device has been tested and the results were mixed: sometimes you get an acceptable profile, sometimes you just get failures. You can read the test results in the Colour Management section at IT-Enquirer.

The third, and probably most cost-effective solution, is to have a third party create your printer/paper profiles. Such a service can cost from 40.00 Euros to well over 200.00 Euros, but most remote profiling services as they are called, are reasonably priced. One good profiling service is Thinck.

For 45.00 Euros they will create a RGB inkjet profile for you. As they are specialised in semi-professional and professional photography, their profile will be specifically checked and tuned for photographers' needs. On Thinck you can also order A3+ prints from HP's newest Photosmart Pro B9180 printer, an excellent 8-colour printer that they drive with EFI's Designer RIP.

About The Author
Erik Vlietinck is the Publisher of IT Enquirer (close new window/tab to return to this page), an online magazine for desktop publishers, graphic designers, and photographers. He also runs a remote profiling service, at www.thinck.com (close new window/tab to return to this page).

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