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0. Complete issue
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- 1. The influence of pH/conductivity of fountain solution on dot circularity, line and text raggedness
- Pages: 1-7
- Jelena Kiurski, Ivana Oros
- Abstract | Download
Abstract
The influence of pH and conductivity of fountain solutions on the quality of dot, line and text raggedness was investigated. Physico-chemical parameters of fountain solutions were analyzed by standard methods. Image quality assessment (IQA) was carried out using the ISO methodology and ImageJ software. There is a great influence of pH and conductivity of fountain solutions on the final quality of magenta prints. Magenta dot circularity on the printed sheets showed the mutual nonlinear dependence, second-order polynomial, followed by equation: y = 0.00514x2 - 0.07524x + 0.78238. Line analysis pointed out the least raggedly edges of 1pt horizontal and vertical lines. Times printed text had the most raggedly edges in comparison with Arial. The results indicated that the dot circularity, line and text raggedness could be useful attributes in the quality control of offset prints.
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2. Hidden infrared image in a uniform CMYK separation hue
- Pages: 8-11
- Ivana Žiljak Stanimirović, Darko Agić, Jana Žiljak Vujić
- Abstract | Download
Abstract
Extended colour management is introduced for integrating the colorants visual characteristics in the visual, but
also in the near infrared spectrum (NIR). Many conventional graphic inks are such that their light absorption in the
visual (V) and NIR specter can be very well measured, and we are using this for our goal which is the following:
firstly to create a double condition of graphic reproduction - invisible graphics to the human eye, but allowing to be
registered by instruments measuring in the NIR area. The second goal is to design graphic elements that are not recognized
in the NIR specter, but are visible so that we can see them. And thirdly: to produce a "double image" with
conventional graphic inks, but in such a way that each image is recognized only in the previously set wavelengths.
This approach introduces modified learning on graphic arts separation where two independent images are joined
in creating CMYK printing channels. The second image as a gray record is the desired black component (K) in the
first visible spectrum image. The standard colour management ends in the visible space (1) but with the help of inks
management, a second hidden image can be developed in the NIR space. Channel K acquires a new meaning. It is
the carrier of its own information in image and text form.
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3. Statistical analysis of printing elements reproduction on thermally developed CTP flexo printing plates
- Pages: 12-22
- Sandra Dedijer, Dragoljub Novaković, Magdolna Pal, Živko Pavlović
- Abstract | Download
Abstract
This study presents statistical evaluation of the dot area and line width on thermally developed CtP flexo printing
plates using image analysis software PerfectEye v4.03. The aim of the study was to determine whether the dot area
and line width when different processing parameters are applied (different main exposure time and different number
of rotations of developing drum during developing process) were statistically different from each other or not. Image
analysis of dots and lines were performed with a VipTronic Vipdens measuring device using CCD camera and
a PerfectEye image analysis software. The shape data, dot area and line width were compared by applying one way
ANOVA (analysis of variance) method followed by post hoc Tukey's test using the software SPSS (Statistical Package
for Social Science) and independent sample T-test with a 0.05 significance level. Statistical analysis revealed
that the difference between the dot area and line width for different processing conditions are significant with a 95%
confidence level.
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- 4. Evaluation of the algorithms for recovering reflectance from virtual digital camera response
- Pages: 23-30
- Ana Gebejes, Ivana Tomić, Igor Karlović, Ivana Jurič
- Abstract | Download
Abstract
have one in common – using digital camera as a capturing device and appropriate image processing method/algorithm
to obtain desired information. With the development of new, more accurate sensors, digital cameras became
even more dominant and the use of cameras as measuring device became more emphasized. The idea of using camera
as spectrophotometer is interesting because this kind of measurement would be more economical, faster, widely
available and it would provide a possibility of multiple colour capture with a single shot. This can be very useful
for capturing colour targets for characterization of different properties of a print device. A lot of effort is put into enabling
commercial colour CCD cameras (3 acquisition channels) to obtain enough of the information for reflectance
recovery. Unfortunately, RGB camera was not made with the idea of performing colour measurements but rather
for producing an image that is visually pleasant for the observer. This somewhat complicates the task and seeks for
a development of different algorithms that will estimate the reflectance information from the available RGB camera
responses with minimal possible error. In this paper three different reflectance estimation algorithms are evaluated
(Orthogonal projection,Wiener and optimized Wiener estimation), together with the method for reflectance approximation
based on principal component analysis (PCA). The aim was to perform reflectance estimation pixel
wise and analyze the performance of some reflectance estimation algorithms locally, at some specific pixels in the
image, and globally, on the whole image. Performances of each algorithm were evaluated visually and numerically
by obtaining pixel wise colour difference and pixel wise difference of estimated reflectance to the original values. It
was concluded that Wiener method gives the best reflectance estimation while produces the best colour fit as well.
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