The choice of RGB working space is crucial in a workflow using ICC Profiles. As the RGB working space is the one used when working on our images in Photoshop, this had to be taken into account when choosing the colour space.
Our philosophy consists of an RGB workflow in which most changes and corrections made to the image should be carried out in RGB in order to create a Masterfile (Digital Transparency), which is then filed and can be used in different ways with the final conversion depending on the output space(s) chosen.
Therefore, when a scanner or digital photography device is acquired, this tool's profile must be applied and the file converted to a working space that results in the smallest possible loss of data. Moreover, the RGB working space should include at very least the entire colour space of the output device(s) that you are planning on using. It would indeed be a pity if some of the values that could be reproduced were removed as soon as the images were opened in Photoshop.
Most conventional working spaces, which are included by default in Photoshop, are derived from video or television standards and are thus very simplistic.
Most printing systems, inkjet, hybrid print runs on photographic paper or even offset, are capable of reproducing more colours than most screens.
A 5000K white point monitor calibration is more suitable when working with photographs with profiles. This is the standard white point used in the graphic arts (including offset).
If a working space with a 1.8 gamma function rather than a 2.2 is chosen, details in shadows can be lost in certain non-print applications. A 2.2 gamma working space would appear to give more uniform results.
The comparison of the different colour working spaces provided by Photoshop below shows that only the Adobe RGB space is suitable for high-volume CMYK printing. However, this colour space has an unsuitable white point of 6500K. This is why German graphic arts specialists created the ECI-RGB colour space, whose gamut encompasses all the reproduction possibilities in an offset press, irrespective of the paper used (both Euroscale Coated and Uncoated and also
Fogra R1-R6). Moreover, this space has a standard 5000K white point.
However, this space is insufficient for photographic applications (printing on hybrid printers such as Fuji-Frontier or Durst-Lambda) and even for high-quality printing on inkjet printers, which are constantly improving. Too many values that can be reproduced on these devices are absent in this space (and furthermore in the standard spaces, Adobe RGB or sRGB, which should be reserved for images to be disseminated on the Internet); mainly in the reds, oranges, magenta, yellow and even the blue and green tones.
This is why specialists looked into this matter and developed several specially designed spaces for photography (in order to retain the values of images taken with digital cameras) and for increasingly high-quality printing. One of these spaces is the DonRGB4 colour space, developed in the USA by Don Hutcheson, a recognised expert in digital acquisition.
These spaces can be used by photographers to produce high-quality photographs and also to print these same images using the CMYK offset process.
