For Visual Assessment, Processing and Output in Premedia and Printing
The roman16 bvdm Reference Images are a publication of the Bundesverband Druck und Medien e.V. (bvdm). The reference images are specially created test motifs for visual assessment, processing and output in premedia and printing. They allow comprehensive statements to be made about colour reproduction and details of the image reproduction in the production process.
The roman16 bvdm Reference Images consist of digital data on DVD-ROM and documentation. The DVD-ROM contains data sets of the images in ECI RGB colour mode and as CMYK separations at a resolution of 700 dpi. The CMYK files are available as 16 bit and 8 bit data. They were converted in Adobe Photoshop CS3 with the Adobe (ACE) CMM (Colour Matching Module) and perceptual rendering intent into ISO Coated v2 (ECI). The current FOGRA39 characterization data, the current ISO Coated v2 (ECI) and the RGB profile eciRGB v2 are also on the DVD-ROM.
The series of roman16 bvdm Reference Images from the Bundesverband Druck und Medien e.V. (bvdm) has been created to allow the whole print and, in particular, premedia production sequence to be checked and assessed. The objective was to develop a series of motifs that formed an aesthetically unified family whilst on the other hand displaying image criteria that are important for their intended purpose as a test system. Long experience has shown that images with a small number of objects are suitable for test purposes. It is important that the problem points are readily and quickly apparent even to new users without words and long searches. The Reference Images reflect this.
In order to be able to bring out differences in colour harmonies and their depiction a reduced image language has been chosen. What this means is that the same image formats, details, lighting, subject distance and the same proportion of person and background are used. Besides the colours, close attention has also been paid to optimal image defi nition in all areas, fine details and image sharpness.
Contents, material nature and plasticity were all made easily readable in a modern and reduced form. The primaries, secondaries and tertiaries are represented in an attractive way through people, accessories, fashion and backgrounds.
The human eye is used as the key judge of the quality of images. For the images in the ECI RGB colour space chromatic tone angles were chosen that approximately corresponded to the off set corner colours. The images are somewhat more colourful but not extremely so, rather they correspond to real scene colours. All the basic colours are covered, especially those where colour deviations can easily have a disruptive effect. These areas lie outside most CMYK colour spaces and are therefore usually adjusted in the separations. When converting into a relatively small colour space, tonal value and detail can be lost and certain areas of the image can appear flat. Tonal value jumps and similar irregularities in smooth gradations are the results of an irregular tonal value distribution. An appropriate gradation is not only present in most of the image. An image in colour and one in black and white (BW) are devoted to each of the highlight, midtone and shadow regions, in order to be able to check the grey axis. In addition, one representative image apiece is devoted to the brown, olive and pastel tones and there is also a highly coloured image. The result is that the roman16 bvdm Reference Images provide a good overview of all the important colour tones of a colour space. In addition, the images contain the broadest possible range of skin tones, where even slight colour deviations can quickly be detected.
The RGB versions of the three black and white images can be used for assessing the grey reproduction and the black composition of CMYK printing profiles. Advertisements with black and white subject matter that are four colour printed for better contrast are an example of where this might be useful.
The CMYK versions of the three black and white images, separations with ISO Coated v2 (ECI), can for example be used for unified evaluation of grey reproduction of a print run and to assess the process calibration (tonal value spread, ink trapping).
The grey scale versions of the three black and white images can also be used to assess the black simulation of a digital proof printing system. Besides black ink, such systems also use the chromatic colours for the simulation of single colour printing with black ink. This can lead to different colour casts in different tonal value ranges of the proof print.
The primary purpose of the roman16 bvdm Reference Images is to check the conversion of RGB data to CMYK data for the chosen printing process. The following applications are of primary interest for the use
|Assessment of different profiles for generating CMYK data from RGB data sets|
|using existing profiles, e.g. ISO Coated v2 (ECI)|
|using self-generated profiles|
|comparison of separation results on the monitor|
|comparison of separation results by means of printed proofs (gamut mapping) and in the print run (black generation, tone value sum)|
|comparison with reference file/CMYK or reference proof|
|Comparing rendering intents (approaches to colour separation)|
|relative colorimetric with black point compensation|
|comparison of colour space reproduction on the monitor|
|comparison of the colour space reproduction by means of printed proofs|
|Checking different versions of CMM (Colour Matching Modules)|