Promjene vrijednosti boja digitalnih slika pri prijenosu međuspremnikom

doctoral thesis

• Title (english): Changes in colour values of digital images during clipboard transfer
• Author: Ivan Pučić
• Mentor: Mile Matijević (mentor)
• Committee member: Ivana Bolanča Mirković (član povjerenstva)
• Committee member: Damir Modrić (član povjerenstva)
• Committee member: Krunoslav Hajdek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Graphic Arts; Zagreb
• Defense date and country: 2021-9-23, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Graphic Technology
• Universal decimal classification (UDC): 655 - Graphic industries. Printing. Publishing. Book trade

Abstract

Zbog razlike između oblika zapisa pojedinih grafičkih alata dolazi do prilagođavanja

podataka prilikom njihovog prijenosa. Ovaj rad istražuje promjene koje nastaju

prijenosom piksel grafika između različitih grafičkih alata korištenjem međuspremnika

kroz određivanje sličnosti fotografija prije i nakon prijenosa te mjerenje razlika u

vrijednostima boja koje su nastale tijekom prijenosa.

U prvom ispitivanju od 132 planirana smjera prijenosa piksel grafika uspješno je

provedeno njih 91. Određivana sličnost fotografija prije i nakon prijenosa, izračunata po

SSIM algoritmu, pokazala je da je u 11 slučajeva izvršen savršeni prijenos, odnosno

prijenosom nije došlo do izmjene strukturnih informacija fotografije. Nadalje, u većini

slučajeva (79,34%) prijenosom je nastala fotografija s malim odstupanjima u strukturi u

odnosu na početnu fotografiju (SSIM indeks iznosi 0,9 do 0,99).

Analizom rezultata drugog ispitivanja pokazalo se da su evidentirane visoke vrijednosti

u razlikama boja nastalih tijekom prijenosa dobivene za boje koje na fotografijama

zauzimaju malu površinu te time nemaju veliki utjecaj na vidljivu kvalitetu prijenosa.

U trećem ispitivanju, usporedbom dobivenih razlika u vrijednostima boja kod prijenosa

grafika u RGB i CMYK prostoru boja, pokazalo se da korišteni prostor boja utječe na

kvalitetu prijenosa, na način da se promjene u vrijednostima boja događaju manje pri

korištenju RGB nego CMYK prostora boja.

Na temelju dobivenih rezultata moguće je potvrditi hipotezu da su promjene u

vrijednostima boja u piksel grafikama nastale prijenosom međuspremnikom uzrokovane

nekompatibilnošću operativnog sustava i grafičkih alata. Nadalje, potvrđeno je da, unatoč

evidentiranim promjenama u vrijednostima boja, transformirane datoteke udovoljavaju

kriterijima i prikladne su za svakodnevnu uporabu. Naposljetku, na temelju dobivenih

rezultata moguće je vrednovanje sustava za upravljanje bojom na razini operativnog

sustava te definiranje preporuka za korištenje međuspremnika. Preporuke idu u smjeru da

je opravdano korištenje međuspremnika za svakodnevnu uporabu, no za profesionalnu

uporabu preporučuje se izbjegavanje prijenosa međuspremnikom. Također, zbog manjih

promjena vrijednosti boja, preporučuje se korištenje RGB umjesto CMYK prostora boja

za prijenos piksel grafika međuspremnikom.

Abstract (english)

The difference in clipboard file formats of the used graphic programs causes the

adaptation of image data during transfer. The transfer of pixel graphics causes the change

in the color values of the pixels. This leads to a visible change in the whole pixel graphics.

This paper researches the changes created during the transfer of pixel graphics between

different graphic programs using the clipboard. The level of changes was determined

through image similarity of the original image and created copies, and the application of

color difference equations of selected color values was also transferred as pixel graphics.

The research showed it was not possible to complete all planned pixel data transfers due

to the incompatibility of the used programs. In the first part, the transfers were completed

successfully in 91 out of 132 planned transfer directions. The similarity measurement of

photographs was calculated with the SSIM algorithm. The perfect transfer was completed

in 11 out of 91 transfer directions, implying that there was no change in the structural

information of the images. A small shift in the structure of the processed pixel graphics

in comparison to the original pixel graphics appeared in 79.34% of the cases. A small

shift is perceived as an index range 0.9 to 0.99.

The analysis of the results in the second part of the research showed a high difference

between colors before and after the transfer for the colors that appear on a small surface

percentage of the photos. This reduces that effect on the color perception of the photo to

a small influence.

The comparison of calculated color differences of the transferred pixel graphic in CMYK

color space (color chart 201101) and RGB color space (color chart 201102) was

performed in the third part. The comparison showed that there is a difference in the shift

of the color values in relation to the used document color space. The shifts in color values

are smaller when RGB color space is used than CMYK-based color space images.

The results show that it is possible to confirm the hypothesis that the changes in color

values of the tested pixel graphics appear during clipboard transfer. They are caused by

the incompatibility of the color management systems of the operating system and usedprograms. Furthermore, it is confirmed that despite the evident changes in color values,

the transformed pixel graphics concur with the quality criteria and can be used in

everyday operations. The obtained results enable the evaluation of the existing color

management systems on the operating system level. They also enable the definition of

recommendations for the use of a clipboard. The use of a clipboard is recommended in

standard everyday use. However, it is not recommended for professional use where color

preservation is essential.

The use of RGB color space is recommended due to the smaller shift in color values

during the clipboard transfer of pixel graphics.

• Keywords: grafički alati; međuspremnik; sustavi boja; operativni sustavi
• Keywords (english): graphic tools; clipboard; color systems; operating system
• Language: croatian
• URN:NBN: urn:nbn:hr:216:781353
• Study programme: Title: Graphic engineering and graphic product design; Course: Graphic technology; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti u području tehničkih znanosti (doktor/doktorica znanosti u području tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-04-24 21:55:24