Color Measurement on Substrates with Optical Brightening Agents

Yellow and blue Pantone colors were printed on a substrate with high Optical Brightening Agent (OBA) levels and then measured under different measurement conditions as outlined in ISO 13655. Both colors exhibited large DEOO shifts with lighter screen tints, as more paper influenced the measurement. The Pantone colors were further analysed after being printed on two different substrates with varying OBAs. While the solids were color-matched to a DEOO of less than 1.0, the tints resulted in DEOO values above 7.0 due to more paper influence in the lighter screen tints

Color Managing for Papers Containing Optical Brightening Agents

The role of a color-managed inkjet proof is to predict and simulate the visual appearance of printed color. The proof-to-print visual match works well under different viewing conditions when the input ICC profile and the output ICC profile, built from characterization datasets, do not contain optical brightening agents (OBA). OBAs influence printed color when measured for characterization and viewed. These brightening agents absorb UV wavelengths in the illuminant and fluoresce in the blue wavelengths. As more and more OBAs are used in printing paper production, the role of color proofing becomes more difficult. The difference in the amount of the UV component of the measuring and viewing light sources cause a problem where the OBA effect, as measured, may not be the same amount of OBA effect that should be proofed under the viewing illuminant. There are two objectives in this research project. The first objective is to show how printed colors, under identical printing conditions on OBA and non-OBA substrates, look different than when they are proofed using current characterization for proofing practices. Both M0 (UV-included) and M2 (UV-cut) measurement data are collected from color patches with selected tonal values and input ICC profiles created from this data are used to proof the brightened reference print. The results show that the UV-cut characterization treatment produces a very poor proof to the reference, while the UV-included proof was ranked as a fairly high match. A third commercially available software designed to improve upon the UV-included treatment, the X-Rite Optical Brightened Compensation module, was also tested and found to be a good match to the reference as well. The second objective is to propose different ways the characterization data can be adjusted for the OBAs in a reference print on brightened paper, by accounting for the influence of UV in the measurement illuminant, and the influence of UV in the viewing illuminant. By means of psychometric analyses, the results show that (1) the proof-to- print match is the worst when OBA in print and UV in the measurement illuminant are not addressed (UV-cut characterization data from M2); (2) although not conclusive, the proof-to-print match improves when OBA in print, UV in the measurement illuminant (characterization data from M0), and UV in the viewing illuminant are addressed

Gamut expanded halftone prints

We propose a framework for printing high chroma and bright colors which are beyond both the display sRGB and the classical cmyk print gamuts. These colors are printed with a combination of classical cmyk inks and the two additional daylight fluorescent magenta and yellow inks. The goal is to enhance image parts by printing them with high chroma and bright colors. We first select the image parts to be enhanced. We then apply to their colors a gamut expansion that increases both their chroma and their lightness towards the colors located at the boundary of the gamut formed by the combination of classical and fluorescent inks. This expansion can be controlled by user-defined parameters. We create smooth chroma transitions between the expanded and non-expanded image parts. We also preview the printable gamut expanded image generated according to user-defined gamut expansion parameters. The resulting prototype software enables artists to create and print their own designs

Print-to-Proof Visual Match Using Papers with Optical Brightening Agents

Optical Brightening Agents (OBAs) are chemicals added to paper pulp whose purpose is to brighten the white point of the paper. Adding OBAs results in a brighter white, increased tonal range, and more chromatic colors. However, adding OBAs can also create problems in visual print-to-proof match where proofing substrates do not contain OBAs. Visual print-to-proof match is the final judge of conformance in a print business. When printing and proofing in conformance to standards and specifications on non-OBA papers, there is visual match between the print and the proof. Printing on OBA loaded papers causes two main problems: (1) difficulty in achieving conformance to printing standards and (2) visual print-to-proof mismatch. To solve the above problems, this research begins by adopting the new M1 measurement condition and the revised ISO 3664:2009 viewing conditions. It then assumes that the print on OBA loaded paper is the anchor and the proof must be color managed to match the print using these new measurement and viewing conditions. In order to test the proposed solution, the researcher prepared a series of prints and proofs that (1) reproduced the proof-to-print match traditionally achieved on non-OBA loaded printing papers (the anchor pair), (2) reproduced the proof-to-print mismatch on OBA loaded printing papers (the problem pair), ix and (3) tested the color managed approach to solving the problem described above (the solution pair). Finally, these pairs were evaluated by a panel of observers in a paired comparison experiment under the revised ISO 3664:2009 viewing conditions. The results of the paired comparison experiment first demonstrated that the researcher could reproduced both a proof-to-print match on non-OBA loaded papers and a proof-to-print mismatch on OBA loaded papers. In addition, the solution pair was demonstrated to be preferred to all other pairs at the .05 level of significance. Finally CIELAB plots of the problem pair and the solution pair under M1 conditions supported the results of the pair comparison experiment. Under M1 conditions the proof-to-print mismatch (difference in CIELAB values) for the problem pair was shown to be approximately twice as large as the proof-to-print mismatch for the solution pair. Based on the results of this research, the proposed solution was shown to be a promising approach for solving the industry wide problem of print-to-proof mismatch when printers print on OBA loaded papers

Interpol review of fingermarks and other body impressions 2016–2019

This review paper covers the forensic-relevant literature in fingerprint and bodily impression sciences from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/ 14458/file/Interpol%20 Review%20 Papers%202019. pdf

Investigation into the removal of pigment, sulphur and vat colourants from cotton textiles and implications for waste cellulosic recycling

Cotton can be coloured by dyeing and printing using either dye or pigment colourants. Pigments are insoluble in water but can be dispersed in a polymer print binder and heat-fixed to the fabric. Vat and sulphur dyes similarly have low solubility in water but through alkali/reduction can be solubilised and exhausted onto the cotton fibre. Following their reoxidation, the dyes are insolubilised in the fibre and, like pigment prints, in general exhibit good wash fastness. In this study, sequential acid/alkali/peroxide or acid/dithionite/peroxide treatments were investigated as a means of removing pigment/polymer prints and common sulphur and vat dyes from coloured cotton fabric. Using the sequential acid/dithionite/peroxide treatment, up to 97% of both sulphur and vat colourants could be “stripped” from dyed cotton producing a white cellulosic feedstock material that could be used for “new” fibre regeneration. By contrast, the “stripping” of the pigment/polymer binder colourant system was less predictable and less complete and is probably a reflection of the different chemical natures of the polymer binder and pigments. This contrasting behaviour highlights the range of chemistries applied to cotton and that developing a universal single treatment to strip out all finishes may be problematic

Test Targets 10: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Th ere are six papers that were written, peer reviewed, and published in Test Targets 10. Two papers focus on printing standardization and conformity assessment. Chung describes aims and tolerances specified in ISO 12647-2 and the use of color measurement and data analysis for conformity assessment. Urbain and Khoury describe data reception requirements in ISO 12647-2 and ISO 15930 and the use of a test pdf file to assess conformity of any pdf workflow. Test Targets 10 will likely be remembered as the publication that covers OBA (optical brightening agents). Two papers focus on OBA. Tian and Chung report the effect of paper containing OBA on printed colors and how such effect can be corrected using different mathematics. Sigg and Millward report the stability of OBA as a function of exposure to light over time. In addition, Gallery of Visual Interest shows side-by-side the visual effect of pictorial and synthetic color images printed on paper with and without OBA. Printing conformity is result-oriented and does not dictate the press calibration method used. The fifth paper, authored by Wang, compares the compatibility of two press calibration methods, TVI and G7, by means of gradation compensation and press run simulation. Printing conformity requires that correct inks and paper be used. Verifying that correct inks are used is outside the capability of a printer. Th e sixth paper, authored by Zhang, explores an alternative ink drawdown and ink verification method that could be implemented by printers. Test Forms is a regular feature of Test Targets. We are pleased to showcase pictorial color reference images, Roman 16 Reference Images, courtesy of Bundesverband Druck und Medien e.V. (bvdm), and many possible uses of these images for printing process control and for color management studies. For example, we can compare the appearance of an image printed from the supplied CMYK file with the image from a supplied RGB file that was converted to CMYK by a color management application

Automatic Media Identification

Català: Identificació automàtica de paper basat en mesures espectrals i de radiació difusa.Castellano: Identificación del tipo de papel basado en medidas espectrales y de radiación difusa.Anglés: Media type identification based in spectral and diffuse measurements

Applications of Small Molecule-Carbon Nanotube Interactions

The interactions of single-walled carbon nanotubes (SWNTs) with small molecules are critical to harnessing their remarkable electronic properties. Due to quenching effects, properties such as near infrared fluorescence are only seen in individually dispersed SWNTs. Individually dispersing SWNTs in aqueous solution using surfactants such as sodium dodecylbenzene sulfate has allowed SWNTs to be studied spectroscopically but only at low concentration. I demonstrate that by combining small molecules additives such as sucrose, trehalose, and glycerine into the surfactant dispersion process, the efficiency of the process is greatly increased. Utilizing the additive sucrose allows for the production of individually dispersed SWNT solutions at a concentration 100 times greater (up to 3.3 g/L) than the highest concentration reported previously. Spectroscopic studies suggest the small-molecule additives do not interact electronically with the surfactant-encapsulated SWNTs in solution but instead increase the solution's viscosity, slowing down Brownian motion of molecules in solution. In solution, SWNTs move slower than surfactant molecules due to the large size difference between the two molecules. After sonication induced cavitation breaks apart a SWNT bundle, the rebundling process is slowed allowing the surfactant molecules more time to stabilize the individualized nanotubes. When dried, the nanotubes from these solutions retain their near-infrared fluorescence, indicating that the nanotubes do not become highly bundled upon solvent evaporation. While the small-molecules do not induce spectral shift in the SWNT solution spectra, in dried films these additives cause the fluorescence of individually dispersed SWNTs to red-shift by nearly 30 nm. Wax based inkjet printing is a popular method to create paper microfluidic devices. The wax is first printed on paper and then reflowed. During reflow, the paper is heated to the wax's melting point causing the wax to wick into the paper and create a hydrophobic barrier. Wax-reflowing is an inexpensive method to create paper microfluidic devices but gives poor resolution due to a high wicking rate in the lateral direction of the paper. To demonstrate how small-molecules such as trehalose can interact with structures other than SWNTs, I studied the transport kinetics of molten wax through paper. When paper is saturated with trehalose, the wax diffuses more slowly in the lateral direction due to blockage of the transport mechanism through cellulose fibers. Transport through larger fiber-created pores is still available but is omnidirectional due to the structure of paper. This mechanism was used to create high-resolution paper microfluidic devices