Transcript
Producing the perfect print from your picture which you have taken great care in editing to look right on screen, is no simple task. You need to consider the appropriate paper to suit the image, what size to print it, and, crucially, how to achieve the colour balance you think you have arrived at on screen. It is also important to understand the limitations of the process in order to get the best result possible. Your monitor can produce a brightness range of 1000:1 but the contrast that print paper can produce is limited by the reflectivity of the paper and the density of black ink, a range of around 100:1. The colours on a monitor screen are produced by a combination of three additive primaries, red, green and blue, whereas the inks used to produce a print are the three subtractive colours, magenta, cyan, and yellow, plus black. Each system is limited in the range of colours or "colour space" that it can represent (see diagram). In terms of the detail that can be represented, a computer monitor uses a grid-like array of light emitting elements or pixels, whereas a printer sprays a very fine stream of micro-droplets onto the paper. Translating the image from screen to paper is therefore bound with limitations, and getting the right result does depend on a measure of skill and judgement, as well as following the correct workflow.
Paper type and image size. There is an almost bewildering choice of papers, and it is as well to consider the sort of work you do and limit your choice to perhaps two or three types, in two or three sizes. Papers broadly divide into two categories, hard surfaces such as gloss or pearl (also called oyster or satin), and soft, watercolour-type matt papers which may have a tinted base. The choice depends on the subject, and is a matter of judgement. As a general rule, the matt papers suit high key subjects, while the satin or gloss papers suit subjects with plenty of impact and sharp definition. You should avoid papers with a strongly tinted base, as these will severely limit your rendering of whites. Print media such as gloss or satin papers often incorporate fluorescing whiteners (as do washing powders) which pick up ultra violet light to give a somewhat unreal ultra white. However, as prints are generally viewed under artificial light which contains no UV, this is unlikely to be a problem. Size your prints according to their intended use. For pictures meant to be viewed in the hand, A5 or A4 are about right. To hang on the wall, A4 can be OK but a
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landscape, for example, would need to be larger, at A3 or A3+. Anything larger would be impressive indeed, and a sharp, well produced A2 print can be stunning, but in practice you would have little need for that size unless you are into public exhibition work. Club competition work at present requires a mounted size of 400 x 500 mm mounted, so that equates to a print size of between A3 and A3+.
Resolution and Sharpness. The question often arises, how many pixels do I need? The answer to an extent depends on what you want the print for. A print which is to be examined closely, in the hand, will need a higher pixel density - or dots per inch on the print, than one intended to be hung on the wall. Have you ever looked at a poster close up? Usually the definition is appalling, but seen from an appropriate distance, it's perfectly acceptable.
Camera
Print Resolution>
Print size @ 200 dpi
Print size @240 dpi
Print size @300 dpi
10 Mpx Compact = 3651 x 2738 px
18 x 13.5
15 x 11
12 x 9
10 Mpx DSLR = 3873 x 2582 px
19 x 13
16 x 10.5
13 x 8.5
12 Mpx Compact = 4000 x 3000 px
20 x 15
16.5 x 12.5
13.5 x 10
12 Mpx DSLR = 4242 x 2828 px
21 x 14
17.5 x 12
14 x 9.5
16 Mpx Compact = 4618 x 3464 px
23 x 17
19 x 14.5
15 x 11.5
24.5 x 16
20.5 x 13.5
16 x 11
16 Mpx DSLR = 4900 x 3266 px
The best quality prints for close viewing will have a resolution of 300 pixels/dots per inch, whilst those for hanging on the wall will be perfectly acceptable at a lower resolution, 200 to 240 pixels/dots per inch. Don't confuse the printer manufacturer's boasts of thousands of dots per inch with resolution. That What's an Unsharp Mask? All consumer figure relates to the micro camera sensors incorporate an anti-alias filter in the droplets, many of which sensor. What this does is to very slightly blur the make up each printed pixel. staircase effect of lines and edges which are diagonal Image sharpening is usually to the sensor, which is a square grid of photo-sites. desirable before printing, but The "alias" in anti-alias is the zig-zag line which because the amount of represents such diagonals. This is mainly a problem sharpening depends on the with low resolution sensors or high magnification type of output (to print or to images. The anti-alias filter very slightly blurs this screen) I usually leave my edge, but in doing so, renders the image less than images unsharpened until I perfectly crisp. The unsharp mask tool finds these am ready to use them. "unsharp" edges and enhances them by locally Sharpening will not put back increasing the contrast either side of them, helping to missing detail - do not define them better. confuse sharpness with resolution. Digital images do
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show some slight softening of edges caused by the anti-alias filter in front of the camera sensor. This can be corrected using the sharpen option in the Lightroom print module, or the unsharp mask in Photoshop. Care must be exercised in using this filter - too much will result in a visible line around edges, which will detract badly from the finished result. A reasonable starting point is 90% to 100% at 1 to 1.5 pixel radius. Better still run some test prints with various sharpening and come to your own conclusions. Some cameras with very large sensors have done away with the anti-alias filter as their rendering is so fine the zig-zag effect on diagonals is to all practical purposes invisible, so in theory they do not need the use of unsharp mask.
Colour management. Colour management is a big subject. It's all about getting the colours you see on your screen onto the paper - or a fair representation of them at least. Many people will trust the default settings of their computer and be perfectly happy with the result, but the more discerning amongst us will quickly identify discrepancies of colour and tone which spoil an otherwise good print. So to get the best and the most predictable result, you need to pay attention to these three important factors:
The colour space (gamut) you are working in The colour rendering of your computer screen (screen calibration) The paper and ink you are printing with (print profiles)
Colour gamut or colour space: As mentioned earlier, colour space is a defined field of colours covering a range of hues, saturations and brightness. The standard colour space that most consumer devices work to is the sRGB colour space (shorthand for sRGB IEC-61966-2.1). Unfortunately, in order to be as universal as possible, this colour space is very limited. Adobe devised a wider colour space for its .psd files to work in and this is the Adobe RGB (1998) standard. Better still is the ProPhoto RGB space. Lightroom operates in a gamut very similar to ProPhoto. If your camera allows you to choose a colour space to record in, always choose the wider colour space. The good news with Lightroom is that you don't have to worry about colour spaces at all. It automatically recognises any colour space profile embedded in an image and works accordingly. If for whatever reason an image has no embedded colour space, Lightroom will assume the sRGB space. The situation with Photoshop and Elements is rather different and less convenient. You need to tell Photoshop what profile you want to work in and what you want it to do when a profile mismatch occurs. It's a bit simpler in Elements, where you have to trust that the software will make the right adjustments based on your simple choice. To do this, in both Photoshop CS and Elements, first you click on Edit, then Colour Settings. See the screen grabs below:
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Elements 12
Photoshop CS4
In the CS4 panel you see I have set Adobe RGB as the working colour space. For a fuller explanation of colour settings, read Martin Evening or Scott Kelby.
Screen Calibration: For serious colour work, a quality monitor is essential. There is no point spending a small fortune on a camera and expecting to see brilliant results on a poor quality screen. Unfortunately many laptop screens fall into this category. Having said that the recent MacBook screens are very good. Although quality monitors are now very accurate, and will represent the full sRGB colour space if not the full Adobe RGB space, it is well worth while calibrating it using an on-screen colorimeter such as the XRite . This runs a test routine on the monitor and creates a profile in your computer's system folder which will then automatically set the monitor colours whenever you switch on.
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You will still be limited by the capabilities of the screen itself, so don't expect an inexpensive monitor to be magically transformed. During calibration, or separately on the better screens, you will be able to set the white balance What is white balance or colour temperature? (white point). I suggest a white There is no such thing as an absolute white. Our point of 6000 to 6500 degrees K, perception of what is "white" is subjective and as this represents midday can vary according to the context in which it is daylight. Also, don't set the seen. If the light source is a red bulb, after a monitor's brightness too high, short period of adjustment we will take the colour remember that the brightness of a sheet of plain paper to be "white". So we range of paper is far narrower define colour temperature instead. This is defined than anything you see on your as the colour of light emitted by a radiating object screen. Altering the monitor's when heated to the specified temperature, in brightness should not alter its degrees Kelvin (Zero Kelvin is -273 deg C, or colour temperature.
absolute zero). So a colour temperature of 4000 degrees K is the colour of light emitted by a radiating object heated to 4000 degrees K. Typical midday sunlight will be around 6500 degK, whereas a domestic lightbulb is around 2500 degK, and an overcast sky high in the Alps can be at 10,000 degK.
Room lighting: Comparing the
print you have just produced with the same image on screen can, even after all the above considerations, still be disappointing. This is usually because the colour balance of the light you are illuminating the print with is nowhere near the colour of your screen. Typical domestic lighting is very red, in the 2500 to 3000 degrees K region. This will emphasise the warm colours and diminish blues and greens. Even quartz halogens are too red. You can however, buy full spectrum compact fluorescents of known colour temperature from specialist suppliers, and these really do help with print assessment. Don't worry too much if your print is to be exhibited somewhere with less than wonderful lighting. The eye adapts remarkably easily to changes in light quality and perceives colours on a relative, not an absolute basis. But for side-by-side comparison between print and screen, you do need the ambient lighting to be somewhere near the colour balance of your screen.
Colour profiles for printing: The output from computer to printer needs to be interpreted to take account of the different characteristics of different papers and printers. This is done by means of a small piece of software called a print profile. Not using these profiles means the result you get will vary from paper to paper and from printer to printer. You can of course, ignore profiles altogether and rely on manually adjusting colours on screen to get a satisfactory result, but a profile does this for you and is easy to apply. All manufacturers of print paper provide profiles for you to download at no cost. You will want profiles corresponding to your printer and the papers you intend to use. Many printers have these profiles built in, but only for the maker's own brand papers. If for example you own an Epson printer and only want to use Epson papers, then you should find the paper listed in the printer control panel, and all you would do would be to select the chosen paper from the menu list before printing.
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Installing ICC printer profiles Download the profile/s you want from the paper manufacturer. This is usually in the form of a zip file. If so, double click to unpack it. Installation using Windows: Right click on the profile file and select "Install Profile" Alternatively, you can manually move it into c:/windows/system32/spool/drivers/color (applies to Windows 2000, XP, Vista, and Windows 7) Installation using Mac OS: Move the extracted ICC profile to the appropriate folder as below: Mac OS 9/9x Move to System folder>Color Sync folder Mac OS X Use Finder to locate User(you)>Library>ColorSync>Profiles Restart the editing application if it was already open. Photoshop and Lightroom will automatically recognise the new profile and include it in the drop-down list (see later)
Printing using Lightroom Printing from Lightroom is very straightforward. You can set up your printer from within the Print module and print one or more images on the same page. Select the picture or pictures you want to print, then go to the Print module. You will find a selection of pre-set templates on the left panel. You can use these or not. And the print layout and process is set up on the right panel. The screen shots on the next page are self explanatory. An important point is to decide whether Lightroom is responsible for colour managing the print, or if the printer is. If you select "Printer manages colour" then in the printer dialogue box you must select the paper type from the drop-down list. If, on the other hand, you want Lightroom to do the colour management, you must disable any colour adjustments the printer would make, again in the printer dialogue box. You can at the same time create a pre-set in the printer dialogue box (see later) which identifies the paper you are using, the media type the printer is to assume (glossy, matt, etc) and the dots per inch (remember this is printer dots, not resolution dots) and any other variables you want to pre-set. A typical printer dialogue box is shown on the next page. This will differ in appearance from printer to printer. Having set up, you can load your paper and print. Any subsequent fine tuning of brightness and contrast can be carried out in the "Print Adjustments" box at the bottom of the right hand panel.
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Detail in these pictures is too small to see on printout, so view enlarged image on screen.
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Printing using Photoshop Elements v12 As with Lightroom, you should decide if you want the printer to do the colour management, or Elements. If the latter, you must disable any colour adjustments the printer may make, in the printer dialogue box. In Elements, Ctrl/Cmnd + O to open the browser (or select your picture from the Organiser), then with it on the Elements editing screen, Ctrl/Cmnd + P to open the print dialogue. A sequence of dialogue panels follows as shown on the screen shot below. In order to select the correct print profile, you need to click on More Options, then on Colour Management. If you want Elements to manage the colours rather than the printer, choose "Elements Manages Colours" then on the drop down box select the appropriate print profile. I suggest that for Rendering Intent, you choose "perceptual" rather than the default "relative colorimetric". The latter maintains the exact relationship between colour numbers, but will clip any which fall outside the gamut, whereas the "perceptual" option will make adjustments to fit the whole range of colour values in the image into that available on print. Generally this gives the better result.
When you reach the printer properties dialogue box, you select the paper listed in the drop-down box, if you want the printer to manage colours. But if you have chosen Elements to manage colours, select "Custom" click "Advanced" and select "No colour management" (or "No colour adjustments") (not shown in the screen shot). Also select the other parameters such as print quality, and if you wish, create a preset for
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that paper which you can come back to and use again in the future. (Creating a preset is explained later).
Printing using Photoshop CS4 The sequence of actions in CS4 is very similar, possibly a little simpler than in Elements, as CS does not assume the user doesn't need to know about things like colour management but puts it in front of them from the outset. Make sure your image is sized correctly for the paper size. (In CS4, hit Ctrl/Cmnd + Alt/Option + I to open the image size panel). A landscape format image will need to be rotated 90 degrees to fit the paper (Image>Image rotation). So with the image open in Photoshop, open the print dialogue with Ctrl/Cmnd + P. As with Elements and Lightroom, you need to decide if printer or Photoshop is managing colours, then the sequence of actions is followed as before. Again, a printer setting preset can be created for each of the paper types you want to use, and they will then appear on the drop down list in the printer properties dialogue box. The screen shot shows I have selected a previously created pre-set, "Permajet Oyster" in the printer settings panel.
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Creating a printer preset The following procedure relates specifically to the Epson 3800. Other makes of printer may differ in detail, but the principles involved will be the same. However, more basic printers are unlikely to have this facility. Start by installing the print profile you want as explained in the text box on page 6. Then open the image you want to print and Ctrl/Cmnd + P to open the print dialogue box. Find the new profile in the drop down box, then click on Page Setup.
In Page Setup, Click Custom, then Advanced. In the Advanced panel, enter the values given by the paper manufacturer for media type, print quality, and "No Colour Adjust"
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Enter name of paper and save the new pre-set.
Your pre-set will now appear in the drop down list of custom settings:
© 2014 Barrie MacJannette
Harrogate Photographic Society
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