Džimbeg-Malčić, Vesna (2005) Primjena Kubelka-Munk teorije i Yule-Nielsenovog efekta na tiskovnim podlogama. Dissertation (PhD) thesis. Grafički fakultet. [Mentor: Bolanča, Stanislav].
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Abstract
U ovom radu provedena su spektrofotometrijska mjerenja tiskovnih podloga, te obojenih otisaka. Otisci su dobiveni klasičnim ofsetom amplitudnom i frekventnom rasterskom modulacijom za osnovna bojila CMYK. Optičke veličine koje karakteriziraju tiskovne podloge i otiske kao što su raspršenje i apsorpcija ispitivani su preko Kubelka-Munk teorije, dok je bočno raspršenje pojava koju opisuje Yule-Nielsenov parametar n. Kubelka –Munk teorija se koristi dugo i uspješno upravo zato jer osnovne optičke veličine tiskovnih površina i obojenih otisaka, opacitet, raspršenje i apsorpciju, opisuje preko reflektancije ili transmitancije koje se eksperimentalno određuju veoma precizno i jednostavno. Murray-Daveisova metoda tokove fotona zbraja linearno, prema zakonu sačuvanja energije fotona, ali daje prevelike iznose reflektancije u odnosu na mjerene. Yule i Nielsen zbrajaju tokove fotona na faktor 1/n, uvodeći na taj način efekt bočnog raspršenja. Eksperimentalno dobiveni refleksijski spektari matematički su obrađeni da bi osigurali neophodne podatke za izračun fizikalnih veličina prema pretpostavkama korištenih teorija. Matematička obrada eksperimentalnih podataka provedena je programima MathCAD 2002 Professional i Data Analysis and Technical Graphics Origin 6.0. Bočno raspršenje svjetlosti u papiru je osnovni uzrok optičkog prirasta rasterskog elementa. Naime, svjetlost koja ulazi u papir između rasterskih elemenata može se bočno raspršiti u papiru prije nego se vrati na površinu kao reflektirana svjetlost. To povećava vjerojatnost da će svjetlost naići na rastersku točku i da će biti apsorbirana. Zbog toga je efektivni udarni presjek apsorpcije rasterske točke veći od fizičke veličine točke. Važno je, prema svemu izloženom, povezati Yule-Nielsenov parametar n, kao mjeru bočnog raspršenja, s fundamentalnim fizikalnim i optičkim parametrima sustava, da bi se preko njih mogla predvidjeti veličina optičkog prirasta rasterskog elementa. Ti fizikalni, odnosno optički parametri su upravo raspršenje i apsorpcija Kubelka-Munk teorije. Na temelju eksperimentalnih mjerenja i matematičkih rezultata odredilo se je područje primjene navedenih teorija s obzirom na realne uvjete grafičke reprodukcije i uspostavila se je korelacija između relevantnih parametara.
| Item Type: | Dissertation (PhD) thesis |
|---|---|
| Mentor name: | Bolanča, Stanislav |
| Thesis Committee: | Bolanča, Zdenka and Parac-Osterman, Đurđica and Bolanča, Stanislav and Milčić, Diana and Mrvac, Nikola |
| Defence date: | 12 July 2005 |
| Abstract in english: | In this thesis spectrophotometric measurements of the choosen paper substrates and coloured prints have been performed. The prints were obtained by classical offset, amplitude and frequency screen modulation, for primary colours CMYK. The optical values which characterize the printing surfaces and prints such as scattering and absorption were investigated according to Kubelka-Munk theory, while the lateral scattering is the appearance which is described by the Yule-Nielsen parameter n. Kubelka-Munk theory has been used successfully for a long time because the basic optical values of the printing surfaces and coloured prints, opacity, scattering and absorption are described by reflectance and transmission which are experimentally determined very precisely and simply. Conservation of photon energy suggest the Murray-Davies method, photon flux add linearly, but the reflectance predicted by Murray-Davies equation is generally higher than the measured reflectance. Yule and Nielsen correct Murray-Davies equation adding photon flux by power factor of 1/n and in that way describe lateral scattering. The fundamental cause of optical dot gain is lateral scattering of light within paper. Light that enters the paper between the halftone dots can scatter laterally within the bulk of the paper before returning to the surface as reflected light. This lateral scattering in the bulk of the paper increases the probability the light will encounter a halftone dot and be absorbed. Thus the effective absorption cross section of the halftone dot is larger than the physical size of the dot. The obtained experimental data of the reflection spectra were processed mathematically in order to obtain the necessary data for calculation of the physical values according to the suppositions of the used theories. Mathematical processing of the experimental data was performed by means of the programs MathCAD 2002 Professional and Data Analysis and Technical Graphics Origin 6.0. According to all the mentioned, it is important to connect the Yule-Nielsen parameters n, as the measure of the lateral scattering, with the fundamental physical and optical parameters of the system in order to foreseen the size of the optical dot gain. These physical, i.e. optical parameters are scattering and absorption of Kubelka-Munk theory. On the basis of the experimental measurements and mathematical results the area of the application of the mentioned theories in regard to the real conditions of the graphic reproduction has been determined and the correlation among the relevant parameters has been established. |
| Uncontrolled Keywords: | Kubelka-Munk koeficijenti, Yule-Nielsenov parametar n, raspršenje, apsorpcija, tiskovna podloga |
| Keywords in english: | Kubelka-Munk coefficients, Yule-Nielsenov parameter n, scattering, absorption, paper substrate |
| Subjects: | TECHNICAL SCIENCES > Graphic Technology |
| Institution: | Grafički fakultet |
| City: | Zagreb |
| Number of Pages: | 175 |
| Callnumber: | 655.344 dži d |
| Inventory number: | 7987 |
| Status: | Unpublished |
| Date Deposited: | 15 Nov 2013 21:47 |
| Last Modified: | 23 Oct 2014 11:04 |
| URI: | http://eprints.grf.unizg.hr/id/eprint/1411 |
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