In a previous article, we showed you that it is impossible to get an identical result on your computer screen and on paper. In short, you’ll need to look into the conversions between the different colour profiles of each tool you use in order to maintain consistency between medium.
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Start Off on the Right Foot
To publish a quality book and to showcase your various creations on paper, you can start by integrating the best practices into your work routine today. When you address colour reproduction early on in your process, you will achieve better results.
Should you Shoot in sRGB, Adobe RGB . . . or RAW?
You may have already chosen the colour space you’re working with on your camera, either sRGB or Adobe RGB. The sRGB space might be more restricted, but it has the advantage of being used by most devices (monitors, tablets, phones). It is the default profile for JPEG files. About 99% of displays use an sRGB profile. Since an sRGB display only displays 76% of the Adobe RGB space, you might conclude that it is better to choose the Adobe RGB space. Well, it’s not that simple!
If you shoot in RAW* format, it doesn’t matter which space you choose because a colour space conversion will be applied to your RAW file when it’s imported to your processing software. With Lightroom and Photoshop software, your photos will be imported in the colour space used by Adobe ProPhoto RGB, which is even wider than Adobe RGB. If one day, technology allowed us to obtain a wide gamut printer-paper combination and maybe even PhotoPro RGB monitors, then RAW would allow you to rediscover nuances that you never would have seen in your images. In fact, there is more information in your files than you can see on your computer screen. Failure to see a colour does not mean that it’s not in your file, but that you are unable to see it.
*RAW file: uncompressed and unprocessed image data captured by a digital camera or scanner’s sensors. Shooting in RAW captures a high level of image detail, with large file sizes and lossless quality. The direct image data means that you start with a high-quality image that can be edited, converted and compressed in a non-destructive manner.
- If you shoot in the sRGB space, your images will immediately be in sync with almost every monitor, tablet and smartphone.
- If, instead, you choose the Adobe RGB space while your monitor is in sRGB, your images will seem dull. You would then have to convert your RAW files to sRGB, which seems absurd.
- In any case, a meticulous photographer should always use the RAW format.
Image Processing
After shooting, importing photos into a computer is the second major step in the process of publishing a colour picture book. It is very important that you have some mastery of the tools to make technology an ally in your project.
To better understand gamut differences, you can use Apple’s ColorSync tool to visualize the different colour spaces (or apply an ICC profile if you’re using Windows). By comparing the Adobe RGB space with the sRGB, you will immediately see that the former is the largest and notably contains a significantly richer range of greens and reds than the latter. With this tool, you can also compare the gamut of your monitor with the one of your selected papers. You will notice that they don’t all have the same colour reproduction capabilities.
How to Choose the Right Monitor to Process Your Images
The sRGB space allows you to display 2.5 million colours while your eye probably only perceives a million, as is the case for most people. If you frequently do fine art prints and can afford it, you can, of course, invest in an Adobe RGB monitor, since this colour space is actually more similar to the space of inkjet presses.
Tip: It is best not to use your laptop to work on your photos, as this type of computer screen can be unstable and usually only has a very narrow viewing angle. Depending on its inclination, you won’t see the colours in the same way. You can, however, use your laptop to sort your photos.Calibrating Your Monitor
The calibration of your monitor is the keystone of your graphic chain. Your monitor should be your reference for the rest of your work.
To calibrate your monitor, you need to purchase a probe. It will allow you to create the ICC profile of your monitor. There are very good probes at affordable prices. In fact, their cost has been divided by about 20 over the past fifteen years. We recommend to use a spectrophotometer*, first because it is much more precise than a colorimeter* and second because it is not very expensive. The X-Rite i1Display Pro, a benchmark in the photography world, costs around US$250 while a similar, smaller model, the X-Rite i1Display Studio Colorimeter, costs US$170. Such a small price difference may not justify depriving you of additional precision.
Source : X-rite
*Spectrophotometer : a more complex colour measuring instrument that factors in the light intensity as a function of the colour. It performs a full-spectrum colour measurement, as opposed to a colorimeter’s tristimulus procedure, and generates colour data that exceeds what the human eye can see.
How often should you calibrate?
Depending on its quality and age, your monitor will need to be calibrated more or less frequently. A good monitor needs to be calibrated at least once a month, and more often if you have a lower-end monitor. Professionals even do it every day.
What Is an ICC Profile Used for?
What’s the difference between a colour space and an ICC profile?
A colour space is a reference, independent of equipment. There are four of them for photography, which are the sRGB, the Adobe RGB, the ProPhoto RGB and the L*a*b space. An ICC profile is a colour space that integrates the colorimetric characteristics of a camera, a monitor or a printer-paper combination. It’s qualified as dependent.
The Main Colour Spaces in Photography
The colour spaces we talked about, sRGB, Adobe RGB, ProPhoto RGB and the L*a*b space, fit together like Russian dolls. Ranging from the sRGB which is the smallest, to the L*a*b which is the largest.
- If you work with a digital camera set to sRGB and you have chosen the RAW format, you know that your photos will be converted to ProPhoto RGB when imported into Lightroom or Photoshop. Current monitor technology does not allow ProPhoto RGB to be displayed;
- If you export your images to a printer who uses a narrower colour space than yours, the more saturated colours will be converted to less saturated ones;
- If you print on an 8, 10 or 12 colour inkjet printer, with a relatively larger gamut, you will get more saturated colours than the printer’s four colour press.
An Example of Conversion From one Space to Another
Source : Vivre de la photo
To sum up, there are three scenarios when creating a file for printing:
2. The visible colour on your monitor is not part of the colorimetric space that can be reproduced by your chosen printer-paper combination. In this case, the ICC profile will establish the best possible match with the closest colour on your printer (also read the frame below “Rendering intent: relative or perceptive?”);
3. The printer-paper combination contains colours that are outside your monitor space, this is particularly true for green colours. In fact, the colorimetric space of the printer-paper combination is much more complex than the one of a monitor. Check it out with Apple’s ColorSync tool (or by applying an ICC profile if you’re using Windows). Why tell you about this when your image does not contain these colours? On one hand, because it is a reality that you must know, and on the other hand, because if you carry out tests with different images using several types of paper, you will find that some are better to reproduce certain colours. For example, you could use a different paper for landscape photos, since the colour green usually occupies a larger part of the spectrum. Test it out and you will see!
Rendering intent: relative or perceptive?
If you work with Lightroom or Photoshop, we think that it’s important to mention the rendering intent. To put it simply, remember that if you choose the perceptive mode, Lightroom will convert your workspace colour to the workspace of your printer while making sure that the adjacent colours are consistent with it. However, in relative mode, Lightroom will only do a one-time conversion for each colour. This second technique can sometimes create an unpleasant edge effect. Depending on your artistic sensibility, and for certain types of images, you may still prefer the relative mode.
Rapido’s Additional Tips
The higher your expectations for colour reproduction are, the more you’ll want to build an efficient workflow. Files produced rigorously will always produce better results than when adjustments are made at the end of the process. By increasing your control over the colour reproduction, you’ll have a greater mastery over your creative work. For instance, this is what we made sure of during our collaboration with the professional photographer Pierre Gauthier, whose black and white photo album enriched in a four-colour process required special care.
Conclusion: The 4 Golden Rules of Colour Image Processing
As you can see, nothing can be left to chance when it comes to moving your images from digital to paper. In this article, we gave you many tips for each step of the process. If we had to name only a few, here is a reminder of the essentials:
2. Be sure to calibrate your monitor before processing your images. If you process your images without calibrating your monitor, it’s similar to crossing the Atlantic with no compass. Have a good trip!
3. Remember that everyone perceives colours differently, and the same applies for all equipment, they always have their own colour space. If you think that your printer will figure it out on their own to reproduce the result you are hoping for, you might be disappointed!
- your camera if you are a photographer;
- your computer screen;
- and your printer or printer’s press.
Interested in this topic ? Discover soon on our blog the 3rd and last article of our series on colorimetry. In particular, we will address the following questions:
- What paper should you use for your art prints?
- The difference between paper stock and grammage
- How to test different papers
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