results of Equinox testing

[Sergey Kuvshinov]

Hallo friends,

My name is Sergey, I from Russia, excuse me for my bad English language.

Allow to acquaint you with reached for today, results of testing of software product , from EskoArtwork company. The product is intended for multicolor separation with use from one to three additional colors.

Testing is spent on the seven-colorful digital printing machine hp indigo press 5000 with use as additional paints Orange, Green, Blue or Violet.

For me as for the production worker, in the course of testing the greatest interest is represented by questions of practical use of a product, possession cost, simplicity of the interface, predictability of options and results of the practical printing. Theoretical bases of Equinox algorithm or details of its practical realisation, at the given sight at a product, fade into the background.

Thus, allow me to acquaint you with impressions of process of practical use Equinox under production conditions.

The most important thing and, perhaps, basic impression of a product: Equinox it was not created for «a shock of foundations» of the printing of images based on subtractive color synthesis. Equinox grows out of evolutionary development of traditional color separation and the printing in a direction of expansion of their gamut.

Basically it is difficult enough to assume other ideology of a product created Mark Samworth, vice- president of company Artwork Systems, the expert in flexographic printing and electronic processing of images.

Equinox corresponds to a class of products classified by me as «Expanded CMYK» or «CMYKPlus» that allows it, not «is inventing a bicycle», to incorporate all the best from the fulfilled algorithms classical CMYK color separation.

Simultaneously Equinox it is possible to carry to a class of the products which algorithm of work is based on tabular transformation of color, that is co-ordinates of color samples of the final image pays off, leaning on ICC profiles of initial and final color model.

Thus, for work Equinox it is required four standard four-color ICC profile. Profiles are created by the standard software for creation CMYK profiles, no multicolor expansions are required. In the course of testing it is used X-Rite ProfileMaker 5 and scale IT8-7/4. It follows from this that any additional skills which are distinct from skills of creation CMYK profiles, from experts of prepress department preparations it is not required.

The first and the basic, in terms Equinox, «Master Profile», is the most usual CMYK a profile created on an invariable scale. Also for work Equinox it is required from one to three ICC profiles for complementary colors, in terms Equinox «Sector Profile» for sectors of a color circle located between the triad cores.

For reception «Orange Sector Profile» the same four-colorful scale in which channel Cyan is replaced on Orange is used. For reception «Green Sector Profile» channel Magenta is replaced on Green, for reception «Blue Sector Profile» channel Yellow is replaced Blue, and channel Black, on Yellow.

All sector profiles are connected independently from each other in menu point «Printing Condition» if any of them is not connected, Equinox turns to system CMYK color separation.

The behavior of algorithm in each of the above described sectors of a color circle copes independently, by means of curves on parameters: «Lightness» «Chroma» «Hue». Parameters are united by the general menu point «Gamut Controls». The major in practical operation, is management on «Chroma», this parameter sets quantity of a complementary color in the final recipe.

By means of parameter «Hue» restrictions on pollution by complementary colors of areas of pure triad colors are entered, management in parameter «Lightness» is applied to restriction of use of complementary colors in areas high lights for the purpose of elimination of problems with formation of local contrasts.

Operating point of the menu second for the importance is the menu «Conversion Settings» in which the most important are the management menu «Source CMYK Profile» and «Black Generation».

On it transfer and the superficial description of managing menu point of Equinox interface comes to an end, its brevity visually shows simplicity of practical use of a product in daily activity of employees of prepress department preparations, and absence of requirement for acquisition of additional knowledge by them and skills. Training by delivery and more exhaustively made "User's guide", with a high share of probability guarantee absence of serious technological problems.

 

[Sergey Kuvshinov]

Now allow to result the short description of the problems revealed in the course of testing and ways of their overcoming.

Problem the first, resulting from ideology of the product, all entering images should comprise profiles of color models, in our case RGB or CMYK. In case of presence of images without a profile, the designer will be compelled to appoint to it that.

Problem the second as resulting from ideology, profiles of target color model should have qualitative «Perceptual» tables.

Problem the third, one way of black generation is accessible to reception to the operator only for predicted color separation result in menu «Black Generation» - «Preserve Black» at which choice the channel black remains invariable at the entrance image in model CMYK or generation black undertakes from a profile of target color model at the entrance image in model RGB. Other options of generation black, initiating own algorithms, are not convincing.

The problem the fourth, in the menu point «Source CMYK Profile» of «Conversion Settings» menu, is available point «Ignore» which, it is expected without being shown on entering RGB images, is not shown and on majority CMYK of images, negatively being shown only on images with deep, neutral shades. The problem is eliminated by accurate understanding of that any entering the image should have a profile of color space, both its absence and ignoring are inadmissible.

On it transfer of the problems revealed in the course of testing allow to finish, and to pass to a statement of problems arising at practical use Equinox, but not connected directly with it.

Problem the first and the basic, resulting from a universal maxim: «it is necessary to pay for all». As Equinox realises algorithms classical color separation and classical technologies of the printing and the black appreciably is applied to formation of the majority of significant, "drawing" details of the image are applied to reproduction of resultants of images. Black generation we have understood, but local contrast, in most cases light, is formed not only dark area, but also light.

In a pursuit for most accuracy of transfer of color Equinox to aspire to use complementary colors there where it only is possible. Owing to what, we, in most cases, receive in light area not two, but three sites of a raster. Problems of classical printing technologies in reproduction high lights are well-known, in digital printing machines and printers they are leveled by addition in technology of colors «Light Cyan», «Light Magenta» etc.

In our case we are limited by an existing set of colors, and to eliminate problems in high lights addition of light colors, we have no possibility. Smooth restriction of generation of the channel of a complementary color is applied to struggle against reduction of local contrast owing to "dimness" of its light area in the field of high lights.

For the same reason, we are compelled to limit presence of a complementary color and in the field of close to a grey axis, that is in neutral area. Leaning against a resultant lightness, algorithm, having added in a compound shade an additional paint, to aspire to reduce in it (at converting from RGB color model) quantity of the black.

Practicing prepress operators immediately will understand that in what good it does not result, clarification of "dark" area and reduction of local contrast inevitably. That it would not occur, generation of the channel of a complementary color in neutral area is smoothly limited.

As reproduction of local contrasts of the image is disturbed very strongly by superfluous generation of a complementary colour in all lightness and saturations range. In case of application of high options of generation of the complementary colors close to a maximum, considerable areas of complementary colors turn to a spot area that is absolutely inadmissible from the point of view of reproduction of details of the image.

As attentive studying, by comparison with RGB monitor, questions of presence of small quantity of complementary colors in areas of the pure triad cores demand. In attempt of creation of the most universal adjustment of menu point «Gamut Controls» parameters five percent of angular extent of each sector in areas of a finding of the triad cores are smoothly masked.

But such decision is justified only for achievement of the maximum universality of options and, to some extent limits possibilities Equinox in achievement maximum colorimetric accuracy of each color sample. It is necessary to understand that creation of the big green button «to make beautifully» it is improbable, and any, most remarkable algorithm does not release the operator from necessity to think.

On it a statement of questions of practical application Equinox allows to suspend temporarily owing to impossibility of their universal illumination within the limits of one message. For illumination and discussion of questions of practical application of technologies multicolor separation and the printing, your obedient servant creates community of practicing printers, designers and photographers under the working name hificolor.ru

The basic information platform of community the site hificolor.ru which domain name is already registered and creation of actually starting maintenance a question of the next several months sees. Any offers, wishes and the help are accepted.

Sergey.

[email protected]