scholarly journals Statistical evaluation of a Color Managed Digital Printing Workflow (CMDPW) consistency [4th C of CMW]

2021 ◽  
Vol 12 (4) ◽  
pp. 17-31
Author(s):  
Haji Naik Dharavath ◽  
Keyword(s):  
Control Charts ◽  
Screening Method ◽  
Calibration Method ◽  
Influential Factors ◽  
Digital Printing ◽  
Color Management ◽  
Random Sample Size ◽  
Software Applications ◽  
Reference Target ◽  
Color Printing

The purpose of this applied research was to determine the Color Managed Digital Printing Workflow (CMDPW) consistency (4th C of the color management) over a period of time [100 days, (N = 100)]. The quality of digital color printing is determined by these influential factors: screening method applied, type of printing process, calibration method, device profile, ink (dry-toner or liquid-toner), printer resolution and the substrate (paper). For this research, only the color printing attributes such as the overall average color deviation [ACD, ΔE (2000)] and the solid ink density (SID) were analyzed to examine the CMDPW process consistency in a day-to- day digital printing operation. These are the color attributes which are monitored and managed for quality accuracy during the printing. Printed colors of the random sample size (n = 80) were measured against the GRACoL2013 standards to derive the colorimetric/densitometric values. Reference colorimetric values used in the analysis were the threshold deviations (acceptable color deviations) as outlined in the ISO12647-7 standards (GRACoL2013). A control charts analysis was applied for further determining the process (CMDPW) SID and ACD variation. The data collected were run through multiple software applications (MS-Excel/SPSS/Minitab) to apply various statistical methods. Analyzed data from the experiment revealed that the printed colorimetric values were in match (aligned) with the GRACoL 2013 (reference/target). Since the SID values of CMYK colors were in control throughout the process, this enabled the CMDPW to produce consistent acceptable color deviation (Average Printed ΔE (2000) = 2.978; SD = 0.437; Acceptable Threshold color deviation is ΔE (2000) ≤ 3.00).

scholarly journals Aiming for G7 Master Compliance through a Color Managed Digital Printing Workflow (CMDPW): Comparison of Compliance with Output Device Profile (ODP) vs. Device Link Profile (DLP)

2021 ◽  
Vol 12 (1) ◽  
pp. 23-35
Author(s):  
Haji Naik Dharavath ◽  
Keyword(s):  
Applied Research ◽  
Screening Method ◽  
Measured Data ◽  
Influential Factors ◽  
Digital Printing ◽  
Output Device ◽  
Reference Target ◽  
The Press ◽  
Color Printing

The purpose of this applied research was to determine the influence of device link profile (DLP) in the color reproduction aimed at the G7 master compliance. The quality of digital color printing is determined by these influential factors: screening method applied, type of printing process, ink (dry-toner or liquid-toner), printer resolution and the substrate (paper). For this research, only the color printing attributes such as the G7 colors hue and chroma, gray balance, and overall color deviations were analyzed to examine the significant differences that exist between the two output profiles [Output Device Profile (ODP) vs Device Link Profile (DLP)]. These are the color attributes which are monitored and managed for quality accuracy during the printing. Printed colorimetry of each profile from the experiment was compared against G7 ColorSpace GRACoL 2013 (CGATS21-2-CRPC6) in CIE L* a* b* space using an IDEAlliance (Chromix/Hutch Color) Curve 4.2.4 application interface with an X-Rite spectrophotometer with an i1iO table. The measured data of each profile were run through this application (Curve 4.2.4). The data were analyzed by using the Verify Tool of the Curve 4.2.4 application to determine the pass/fail of G7 master compliance levels using G7 ColorSpace tolerances (G7 Grayscale, G7 Targeted, and G7 Colorspace). Analyzed data from the experiment revealed that the printed colorimetric values of each profile (G7 Grayscale, G7 Targeted, and G7 Colorspace) are in match (aligned) with the G7 master compliance levels (reference/target) colorimetric values (G7 Grayscale, G7 Targeted, and G7 Colorspace). Therefore, the press run was passed by the Curve 4 application for both the profiles used/tested towards aiming for G7 master compliance.

scholarly journals Aiming for G7 Master Compliance through a Color Managed Workflow: Comparison of Compliance with Amplitude Modulated (AM) vs. Frequency Modulated (FM) Screening of Multicolor Digital Printing

2021 ◽  
Vol 12 (2) ◽  
pp. 5-18
Author(s):  
Haji Naik Dharavath ◽  
Keyword(s):  
Screening Method ◽  
Measured Data ◽  
Influential Factors ◽  
Digital Printing ◽  
Color Reproduction ◽  
Printing Process ◽  
Reference Target ◽  
The Press ◽  
Color Printing

The purpose of this research was to determine the influence of screening technologies (AM vs. FM) in the color reproduction aimed at the G7 master compliance. The quality of digital color printing is determined by these influential factors: screening method applied, type of printing process, ink (dry-toner or liquid-toner), printer resolution and the substrate (paper). For this research, only the color printing attributes such as the G7 colors hue and chroma, gray balance, and overall color deviations were analyzed to examine the significant differences that exist between the two screening technologies (AM vs. FM). These are the color attributes which are monitored and managed for quality accuracy during the printing. Printed colorimetry of each screening from the experiment was compared against G7 ColorSpace GRACoL 2013 (CGATS21-2-CRPC6) in CIE L* a* b* space using an IDEAlliance (Chromix/Hutch Color) Curve 4.2.4 application interface with an X-Rite spectrophotometer with an i1iO table. The measured data of each screening were run through this application (Curve 4.2.4). The data of each screening were analyzed by using the Verify Tool of the Curve 4.2.4 application to determine the pass/fail of G7 master compliance levels using G7 ColorSpace tolerances (G7 Grayscale, G7 Targeted, and G7 Colorspace). Analyzed data from the experiment revealed that the printed colorimetric values of each screening (G7 Grayscale, G7 Targeted, and G7 Colorspace) are in match (aligned) with the G7 master compliance levels (reference/target) colorimetric values (G7 Grayscale, G7 Targeted, and G7 Colorspace). Therefore, the press run was passed by the Curve 4 application for both screening technologies tested.

scholarly journals Radiometric Calibration for Incidence Angle, Range and Sub-Footprint Effects on Hyperspectral LiDAR Backscatter Intensity

2020 ◽  
Vol 12 (17) ◽  
pp. 2855
Author(s):  
Changsai Zhang ◽  
Shuai Gao ◽  
Wang Li ◽  
Kaiyi Bi ◽  
Ni Huang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spatial Information ◽  
Incidence Angle ◽  
Incident Angle ◽  
Calibration Method ◽  
Correction Method ◽  
Intensity Data ◽  
Radiometric Calibration ◽  
Backscatter Intensity ◽  
Reference Target

Terrestrial hyperspectral LiDAR (HSL) sensors could provide not only spatial information of the measured targets but also the backscattered spectral intensity signal of the laser pulse. The raw intensity collected by HSL is influenced by several factors, among which the range, incidence angle and sub-footprint play a significant role. Further studies on the influence of the range, incidence angle and sub-footprint are needed to improve the accuracy of backscatter intensity data as it is important for vegetation structural and biochemical information estimation. In this paper, we investigated the effects on the laser backscatter intensity and developed a practical correction method for HSL data. We established a laser ratio calibration method and a reference target-based method for HSL and investigated the calibration procedures for the mixed measurements of the effects of the incident angle, range and sub-footprint. Results showed that the laser ratio at the red-edge and near-infrared laser wavelengths has higher accuracy and simplicity in eliminating range, incident angle and sub-footprint effects and can significantly improve the backscatter intensity discrepancy caused by these effects.

Printing with light: daylight–fluorescent inks for large-gamut multi-color printing

2019 ◽  
Vol 2019 (1) ◽  
pp. 170-176
Author(s):  
Peter Morovic ◽  
Ján Morovic ◽  
Peter Klammer ◽  
Javier Maestro ◽  
Garry Hinch ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Uv Radiation ◽  
Color Management ◽  
Basic Assumptions ◽  
Separate Layer ◽  
Color Printing ◽  
New Challenges ◽  
The Impact ◽  
The Way

With printing technologies continuously reaching ever higher degrees of performance and quality, the need for novelty and impact and also keeps increasing. Specialty inks have always played an important role here, albeit not without challenges. Often the use of such materials involved dedicated solutions that deal with these inks outside of the constraints of normal pipelines and workflows, which constrains their application and results in limited use. This is so since specialty inks, such as fluorescents, behave differently to traditional dye or pigment-based ones. So much so that most applications use specialty inks as spot colors, explicitly determining (by means of a separate layer in the input) where they are to be used for given content. For example, for materials such as fluorescents or quantum dots, the possibility of presenting more light at a given wavelength than is incident at that wavelength, breaks some of the basic assumptions of current processes, from how they are measured to how they can be used in building color separations all the way to how color management deals with them. In this paper we describe first experiments of using fluorescent inks that are activated by visible – instead of the more customary UV – radiation, showing performance of spectrophotometer measurement with a dedicated model to handle the specific properties of these inks, as well as results of the impact such inks can have on extending color gamuts that go significantly beyond current printing gamuts and therefore also pose new challenges.

A precise method of color space conversion in the digital printing process based on PSO-DBN

2022 ◽  
pp. 004051752110672
Author(s):  
Zebin Su ◽  
Jinkai Yang ◽  
Pengfei Li ◽  
Junfeng Jing ◽  
Huanhuan Zhang
Keyword(s):  
Neural Network ◽  
Color Space ◽  
Back Propagation ◽  
Optimal Solution ◽  
B Value ◽  
Digital Printing ◽  
Generalized Regression Neural Network ◽  
Color Management ◽  
Printing Process ◽  
Color Space Conversion

Neural networks have been widely used in color space conversion in the digital printing process. The shallow neural network easily obtains the local optimal solution when establishing multi-dimensional nonlinear mapping. In this paper, an improved high-precision deep belief network (DBN) algorithm is proposed to achieve the color space conversion from CMYK to L*a*b*. First, the PANTONE TCX color card is used as sample data, in which the CMYK value of the color block is used as input and the L*a*b* value is used as output; then, the conversion model from CMYK to L*a*b* color space is established by using DBN. To obtain better weight and threshold, DBN is optimized by a particle swarm optimization algorithm. Experimental results show that the proposed method has the highest conversion accuracy compared with Back Propagation Neural Network, Generalized Regression Neural Network, and traditional DBN color space conversion methods. It can also adapt to the actual production demand of color management in digital printing.

Effects of Dot Configuration on Color Reproduction and Anti-counterfeiting Features

2020 ◽  
Author(s):  
Raymond Chiang ◽  
Pei-Li Sun
Keyword(s):  
Screening Method ◽  
Error Diffusion ◽  
Color Management ◽  
Shape Error ◽  
Color Reproduction ◽  
Two Stage ◽  
Color Quality ◽  
Raster Image ◽  
Color Differences ◽  
Continuous Tone

This study represents an attempt to solve the problem of color reproduction and identification for the prevention of stamp forgery. Generally, printed images are converted to halftone dot patterns by using a raster image processor. The amplitude-modulated dots of each separated color plane have a consistent shape such as conventional round, square, ellipse, or diamond shape; error diffusion occurs in frequency-modulated dots. To achieve anti-counterfeiting properties for stamp reproduction, two methods are proposed to obtain difficult-to-replicate dot structures and to provide corresponding color management methods. The first method involves arranging different dot shapes in different areas of an image. Color consistency is achieved using a virtual gray balance method. However, color differences are visible when two dot types are assigned to adjacent areas with similar colors. The second method is a two-stage screening method. The first screening stage defines different micro-regions in the image, which are then combined with the continuous-tone image again in the second screening step to assign different dot patterns to different micro-regions. This approach not only provides anti-counterfeiting ability but also ensures color consistency and allows controlling color quality using one ICC profile.

Rapid Calibration Method for 3D Laser Scanner

2020 ◽  
Vol 14 (2) ◽  
pp. 234-241
Author(s):  
Bin Liu ◽  
Qian Qiao ◽  
Fangfang Han
Keyword(s):  
Laser Scanner ◽  
Vertical Direction ◽  
Calibration Method ◽  
Intrinsic Parameters ◽  
Average Value ◽  
Light Plane ◽  
Imaging Model ◽  
Reference Target ◽  
Camera Intrinsic Parameters ◽  
Rapid Calibration

Background: The 3D laser scanner is a non-contact active-sensing system, which has a number of applications. Many patents have been filed on the technologies for calibrating 3D laser scanner. A precise calibration method is important for measuring the accuracy of the 3D laser scanner. The system model contains three categories of parameters to be calibrated which include the camera intrinsic parameters, distortion coefficients and the light plane parameters. Typically, the calibration process is completed in two steps. Based on Zhang’s method, the calibration of the camera intrinsic parameters and distortion coefficients can be performed. Then, 3D feature points on the light plane should precisely be formed and extracted. Finally, the points are used to calculate the light plane parameters. Methods: In this paper, a rapid calibration method is presented. Without any high precision auxiliary device, only one coplanar reference target is used. By using a group of captured images of the coplanar reference target placed in the field of view arbitrarily, calibration can be performed in one step. Based on the constraint from the planes formed by the target in different directions and the camera imaging model, a large amount of 3D points on the light plane can easily be obtained. The light plane equation in the camera coordinates system can be gathered by executing plane fitting to the 3D points. Results: During the experimental process, the developed 3D laser scanner was calibrated by the proposed method. Then, the measuring accuracy of the system was verified with known distance in vertical direction of 1mm with sequential shifting motion generated by precision translation stage. The average value of the measured distances was found to be 1.010mm. The standard deviation was 0.008mm. Conclusion: Experimental results prove that the proposed calibration method is simple and reliable.

scholarly journals Developments and Progress in Non-contact Eye Tonometer Calibration

2020 ◽  
Vol 20 (4) ◽  
pp. 171-177
Author(s):  
Peter Pavlásek ◽  
Jan Rybář ◽  
Stanislav Ďuriš ◽  
Branislav Hučko ◽  
Miroslav Chytil ◽  
...  
Keyword(s):  
Optical Sensors ◽  
Calibration Method ◽  
Influential Factors ◽  
Measurement Standard ◽  
Detailed Characterization ◽  
Non Invasive ◽  
Air Stream ◽  
And Control ◽  
Traceable Calibration

AbstractThis paper focuses on the problematic of intraocular pressure (IOP) measurements, performed by non-invasive methods. More specifically, the devices that are connected with the presented finding are non-contact tonometers that use concentrated air stream and optical sensors to determine the IOP within a human’s eye. The paper analyzes various influential factors that have an effect on the determination of the IOP values originating from the patients themselves and from the non-contact tonometer devices. The paper furthermore elaborates on the lack of independent methods of calibration and control of these devices. In order to fill this gap a measurement standard device that is capable of calibrating and testing these devices with traceability to the basic SI unit is presented. A detailed characterization and the determination of the expected uncertainty of the device are provided. By introducing an independent and traceable calibration method and control of non-contact tonometers into the clinical practice, the reliability of the measured IOP that is the primary indicator of glaucoma can be improved.

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