Printing Images

“The philosophy set forth in these books is directed to the final expression of the photographer’s visualisation - the print.”    Ansel Adams

The Ansel Adams Photography Series: Book 3 (1980) p1.  Little, Brown and Company New York.  ISBN 978-0-8212-1526-5-HC

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I really enjoy printing my images and it’s great to hold in my hands the final result of my creative endeavours.  In the analogue era, once the shot had been taken, apart from sending the film to be developed, the job was done.   Today, the photographer is in charge of the whole process from pressing the shutter, reviewing the image on the camera, developing the digital image on a computer, to printing the picture.  We have become image makers. 

There are many challenges in producing top quality prints.  And to ensure success, it is important that the complete printing work flow is carried out using icc profiles as defined by the International Color Consortium (established in 1993 by eight international companies including Adobe, Apple and Microsoft)

Profiling the computer monitor

It used to strike me as odd that in large electronic stores with many televisions showing exactly the same programme they would have widely differing pictures, some highly saturated with much contrast, others pallid in comparison; and most somewhere in between.   TVs use composite video signals in which the colours have been mixed together; and they are then adjusted to individual taste by the viewer.  Unlike TVs, computer monitors use three separate electron guns, one each for red, green and blue (RGB) to fire electrons at the monitor screen which generates a spectrum of colours.  

To an image maker this is important because if our computer monitors were to vary to the same degree as those TVs then an image on my monitor might look entirely different when it is displayed on your monitor.  However, if both monitors have been profiled by comparing each to an appropriate international standard then the image would look the same on both.  

Profiling a computer monitor involves using a device (colorimeter or spectrophotometer) to measure variables such as the brightness of the monitor, the white point and the black point as well as the outputs of the red, blue and green colour guns.  The device will also measure a number of grey points.  (RGB icc colour spaces such as sRGB and Adobe (1998) RGB are balanced colour spaces in that when the R, G and B numerical values are identical the resulting colour is a grey: for example, RGB 0,0,0 is black; 60,60,60 is a dark grey; 128,128,128 is mid grey; 190,190,190 is a light grey; and 255,255,255 is white).

The colorimeter or spectrophotometer attaches to the computer usually by USB.   It is then placed on the front of the monitor so that the light emitted by the monitor can be measured.  Common examples of such devices are X-Rite ColorMunki Display and the X-Rite i1 Display  PRO (http://www.xritephoto.com/displaycalibration).  Having measured the output from the monitor, the device then integrates with specialist software in the computer to instruct you to make specific alterations to your monitor output so that it becomes compatible with the icc standard.  And now, when you look at the image on your icc profiled monitor, you will know that it appears as it would to others using their icc profiled monitors.

Profiling the printer

When you send a digital image file from your computer to your printer the data you send include the RGB numbers of all the colours in the image.  If your computer monitor has been suitably icc profiled you will be confident that the data being received by the printer represent accurately the true colours of your image as seen on your monitor.  

But, how do you know that your printer will accurately print the colours received from your digital image file?  You don’t know unless you profile your printer.  The printer icc profile takes into account the specific paper, ink and the printer that you are using.

Some papers are vey white and others perhaps a little off-white.  Some papers absorb a lot of ink whereas others are less porous.  Ink from one manufacturer will interact with the paper differently to the ink made by another.  The printer needs to be informed about these various variables so that it can accurately reproduce the colours in the image file received from your computer.

An icc printer profile is obtained by first using your printer to print an image file with a wide range of different colours, usually arranged like a decorator’s colour chart, in which the relationships between the various colours and their RGB numbers have been verified.  So, for example, if a colour in the image chart has the verified RGB value of 19,25,31 (dark blue/green) your printer should provide the inks in suitable amounts to deliver that exact colour on that particular photo paper using that particular type of ink.  However, it will only be able to achieve this objective if it has been already informed about the paper type (brightness, absorbency etc) and the ink type (Epson, Canon, non-OEM ink etc).  

Initially, the print can be made using your printer and the paper and ink of your choice in the knowledge that the printed colour will not be accurate.  Having obtained the print it is then possible to use a spectrophotometer to measure the actual RGB numbers of the colour which has been printed onto your photo paper by your printer.  It is most unlikely that the RGB numbers of that dark blue/green colour will be 19,25,31 when initially printed by your printer.  However, the difference between the actual printed colour and the desired printed colour can now be evaluated and used to generate some computer software which will tell the printer the adjustments it needs to make to achieve accurate colour using that specific paper and that specific ink.  

Most photo paper manufacturers provide for their papers free generic icc profiles for use with a wide range of ink/printer combinations.  These icc profiles are pieces of computer software which can be downloaded from the manufacturer’s web site to your computer so that appropriate information is sent to the printer with the image file to inform the printer about how it should interpret the RGB data to obtain accurate colours.  These generic icc profiles are usually sufficiently good to ensure faithful colour representation.  

However, if for any reason you are unhappy with the paper manufacturer’s generic profile for your printer/ink combination, you can obtain a profile for a specific paper, a specific ink and your own personal printer.  This process involves printing on your personal printer an image file which has been sent to you by the profiling company of your choice.  The resulting print is then sent back to the company for analysis following which the company will send to you by email an appropriate piece of software to be installed in your computer so that your personal printer will print accurate colours with that specific paper and ink combination.  This ensures an extremely accurate icc printer profile for that paper and ink.

Comparing the monitor image with the printed picture

If both your computer monitor and your printer are appropriately icc profiled your printed image will look very similar to the image you see on your monitor: very similar, but not the same.  There are inescapable, fundamental differences between the printed image and the projected image  We see the image on the monitor via direct, projected light coming directly from the screen into our eyes and the colours are bright and vibrant.  Monitor images benefit if viewed in a dark environment rather daylight.  With respect to the print we see the image via indirect light where the rays hitting the printed paper are reflected into our eyes.   Printed images benefit from being viewed in full daylight rather than a dark environment.  Because of these physical differences, compared to monitor images printed images appear relatively flat and dull.

Computer programmes such as Adobe Lightroom and Adobe Photoshop enable the monitor image to be ‘soft-proofed’ such that the computer emulates how the image will appear in print with a specific icc printer profile.  When you soft-proof the image on your monitor be aware that your image will perforce become less punchy and less vibrant.  

However, if your both computer monitor and printer have been properly icc profiled, when you pick up your picture after it has emerged from the printer and you hold it up to the daylight, it will compare very favourably with the soft-proofed image that you see on your computer monitor.  You have a product which will last for generations.  And that is very gratifying!   

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