Commercial systems dedicated to assess print quality already exist. They usually implement the ISO 13660 standard with a focus on character and line attributes (raggedness, line width, darkness, character, contrast, fill, extraneous marks, character field, background haze, character field)

However, they are expensive, lack of flexibility and the access to their algorithms is not possible.

Fiji/ImageJ and its environment enables to develop an open source program dedicated to print quality assessment› free license› Interface based› Development using Java language and pre-coded functions› Enhance collaboration

Registration mark

Features extraction

Statistical analysis

Print target design

Choice of relevant features

High resolution & low field of view vs low resolution & high field of view

Printing sequences

Inter-samples

Intra-samples

Dot

Lines

TextLighting conditions

Image acquisition

Printing

Fiji

Printing parameters(drop speed,…) Substrate

Ink

Printing configuration

System model

Dithering techniques

Fiji is an image processing package. It can be described as a distribution of ImageJ together with Java, Java 3D and a lot of plugins.

User interface

Macro/plugings editor

Individual ‘bricks’-Color conversion-Binary analysis-Illumination correction-…

Increase productivityAutomationShorter development timeProprietary routines and development of standard

Software development MacroJava based program

Image creation to design test charts

Dithering techniques

Dots and satellites

Line width/raggedness

Series of parallel lines

By example, test of optical density regularity along the swathe › Periodic pattern

› Random pattern

Comparison and impact of different dithering techniques

Implementation of algorithms specific to greyscale printhead

Background subtractionRGB – one layerBinarization

Particles extraction Particles counting

Histogram for a given parameter

Individual object’s properties

› Edges extraction + angular correction + average and standard deviation on both sides of the line

Idea

di

%

di

Histogram

REFERENCE

Original image

The centre of each line is computed to obtain the distance between two successive lines

The histogram is then plotted

implementation The red circles represent the middle of the line

Average and standard deviation are then calculated

Colour deconvolution

Results tolerance

Text recognition and limit of “readability”

Objective: to quantify colour variations caused by due to undesirable drops overlap,...

Colour clustering

in RGB space

Colour split

Placement accuracy

% of coverage

Printing direction

Dithering techniques

Objective: to evaluate the interval of confidence for results like dot diameter, (x,y) positioning, roundness,…

Pixel size: 2 mDot diameter: 60 m

Distribution of error centred of the theoretical dot area

Algorithm based

on dot permutation

Image analysis is an approach, but not the end of the story

PQ can be described along several others physical dimensions (Optical density, colour gamut, full tone uniformity…)

Some levels of overlapping exist between them

If you:› want to know more about ImageJ / Fiji› are interested in developing an ISO13660

open source software› have a specific need regarding print

quality assessment, beyond image analysis

I would be please to heard from you.