Analyzing & Measuring Print Quality. Yair Kipman ImageXpert, Inc. Nashua, New Hampshire

Transcription

1 Analyzing & Measuring Print Quality Yair Kipman ImageXpert, Inc. Nashua, New Hampshire

2 Presentation Outline What is print quality? Why should you measure print quality and how should you measure it? Advantages of objective print quality analysis Benefits of objective analysis Issues with subjective analysis Benefits of measuring print quality throughout product lifecycle What can you measure? General print quality attributes Toner-specific attributes Inkjet-specific attributes Measurement tools and instruments Live demo

3 What is Print Quality? Prints Contain... Text Halftoned regions or images Outlines or diagrams (line art) Solid areas Gray scale Color...

4 What is Print Quality? Print quality is the perceived or measured quality of a printed image In other words, how does the print look? Is the text sharp? Are edges blurry? Is the image noisy? Are there spots? Bands? Is it blotchy? Are edges ragged? Is there inter-color bleed?...

5 Why Should You Measure It? While price is an issue, so is quality Print quality is what people see How Should You Measure It? There are two main ways to assess print quality: Subjective evaluation (visual assessment) Objective evaluation (instrumented analysis)

6 How Should You Measure It? Why Not Use Visual Assessment? Because visual assessment is inconsistent Visual assessment is inherently subjective Different observers may return different results Fatigue and changes in energy level can skew opinions The process is incredibly time consuming and tedious

7 How Should You Measure It? Data recording,tracking, archiving Takes too long to enter information manually into database and,manual data entry is prone to errors Statistical information is not readily available Only when you gather data over long periods of time can you assess product quality trends Conclusion: Visual print quality inspection may not be sufficient

8 How You Should Measure It: Objective print quality analysis uses instruments to assess the characteristics and attributes that make up the print and impact the perception of overall print quality Some of this analysis is highly detailed Lines, dots, text Some is more macroscopic Solid area mottle (blotchiness), banding...

9 How You Should Measure It: Objective print quality analysis is repeatable and objective Not dependent on operator or inspector repeatable over time Quantitative Numeric results for tracking, measurement against performance goals Can be automated You can save money and time on the inspection process by automating print quality analysis and data collection

10 Measure Print Quality Throughout Your Product Development Cycle Different points in the product development cycle can benefit from objective print quality assessment Benchmarking R&D Production

11 Measure Print Quality Throughout Your Product Development Cycle Benchmarking Know your competition (OEM s and other remanufacturers) Determine desired print quality levels Set quantitative performance goals

12 Measure Print Quality Throughout Your Product Development Cycle R&D Analyze your performance against goals Track improvements during development Use information to change formulation or choose appropriate vendors to meet quality levels Communicate success and outstanding issues clearly Characterize print quality during life testing

13 Measure Print Quality Throughout Your Product Development Cycle Production Measure consistency by tracking product quality over time Check performance against pass/fail tolerances

14 Short Note on Cartridge Yield It is important to check printability throughout the full life cycle of a cartridge since initial print quality may deteriorate over time Quantify performance over time Check against pass/fail tolerances to determine actual performance versus goals Compare performance to competitors and OEMs

15 Short Note on Returned Cartridges Cartridges are returned for many reasons. Many reasons may be out of your control. But unacceptable print quality is avoidable For every returned cartridge you lose: Time Shipping costs Replacement cartridge MOST IMPORTANT--YOU MIGHT LOSE A CUSTOMER! Options? Check the print quality before shipping.

16 What You Can Measure: General Print Quality Measurements for both Ink & Toner

17 Line Quality Line quality can be quantified by a number of characteristics such as: Average line width Edge raggedness Line area

18 Text Quality Measuring text quality can highlight and quantify differences between OEM and third party colorant sets Common features include: Character area Perimeter length Edge raggedness Detection of breaks Detection of fill-ins Extraneous noise (satellites, toner scatter)

19 Dot Quality Common measurements for positive dots include: size (area) shape (roundness) perimeter length darkness Common measurements for negative dots include: number of dots size (area) lightness Both statistical data and data from individual dots can be reported Primary dots and satellites can be measured separately

20 Solid Area Quality Solid area mottle is a macroscopic variation in solid area density Analysis requires low-magnification image capture of a relatively large area often using a scanner Multiple mottle measurement methods include: Simple statistics (standard deviation) ISO/IEC using tiled cells or a moving ROI Cluster-based analysis

21 Halftones Halftone quality impacts system tone reproduction Common measurements for halftones include: area coverage gray average

22 Resolution Resolution patterns indicate how well a system can render detailed image features Measure in both horizontal and vertical orientations Common measurements include: Line to space width ratio Dynamic range comparison Pattern contrast...

23 Toner-Specific Print Quality Measurements

24 Area Coverage Area coverage is a commonly measured image quality feature for toner-based systems and is often used as a method to determine endof-life for cartridge yield testing Measure percent area coverage of printed area on page

25 Black Density and Tone Reproduction Step 1 Step 2 Measure the density or gray value of the gray patches Assess highlight and shadow detail Step 3 Step 4 Step 5 Step 6 Step 7

26 Fix/Crease/Toner Adhesion Toner adhesion refers to how well the toner is fixed to the paper. If is it not suitably fixed, it will rub or scratch off easily. There are three common ways of measuring toner adhesion: Crease test-measure crease width, brightness, area Abrasion test- measure area before and after abrading Tape pull test-measure tape or area before and after pull test

27 Toner Scatter Toner scatter is toner that has been developed adjacent to a printed feature such as a character, line or solid area Measure number of spots Measure spots within a given distance of the edge of a feature such as a character or line Measure the amount of toner scatter at various distances from the edge of a feature

28 Banding Banding can be light or dark, random or periodic, horizontal or vertical Measure random banding by sharpness, size, position and contrast Measure periodic banding via FFT, periodicity

29 Residual Image and Ghosting Ghosting is a light or dark image of a feature repeated in a printed or non-printed area some set distance from the original feature Compare the density or gray value of an area immune to ghosting to the density or gray value of an area prone to ghosting Often, ghosting (or residual images) occurs along with banding so careful measurement is necessary

30 Background Background is toner that has been developed in the background area including those areas well away from printed features. Measure gray average Measure area coverage Measure the number of spots in a given size range in a given area Measure background via RMSGS method

31 Inkjet-Specific Print Quality Measurements

32 Jet Quality Non-firing or misfiring jets can result in visible defects Banding Poor character quality Jet health attributes include: Missing jets Misdirected jets Jet segmentation...

33 Inter-Color Bleed Inter-color bleed is the unintentional intermixing of adjacent colorants It can be assessed macroscopically using scanned images, or in a more detailed fashion using highermagnification images Different color combinations often have different quality levels Common measurements include comparisons of: line width edge raggedness edge sharpness

34 Satellites/Overspray Satellites and overspray impact quality of everything from edges to halftones to text Number and size of satellites can be reported Satellites can also be counted a different distances from an object or feature

35 ImageXpert s Product Line

36 ImageXpress For high-magnification image analysis High-resolution image capture Compact measurement head and laptop computer enable portability Firewire camera technology for increased field of view Integrated light source The full power of ImageXpert software for image analysis

37 ImageXaminer Scanner-based image analysis Economical image analysis system 1600 or 2400 dpi optical resolution Color or gray scans Accommodates samples up to A3+ size ADF for full automation The full power of ImageXpert software for image analysis

38 Full Motion System For high volume high-magnification image analysis Fully automated Ideal for large volumes Use in both R&D and production Multiple cameras allow multiple resolutions for image capture Fully integrated instrumentation can be added such as an X-Rite for color measurement and a gloss meter

39 Note on Calibration For all camera-based systems, our calibration process provides three main benefits: Translates pixels into real-world units such as millimeters or inches (using a NIST traceable calibration target) Accommodates for any distortions caused by the camera alignment or optics Ensures that data collected by that system when it is in a calibrated state at one point in time is comparable to data collected via the same methods by the same calibrated system at a different point in time Remember: An image quality system without calibration is virtually useless

40 What is the Return on Save time Investment? One customer reduced inspection time from 4 minutes per sample to 1 minute per sample Use resources more efficiently Automated systems do not require the same level of expertise as visual inspections Anyone can use the system once it is set up You can use objective data to track improvements in product quality

41 Checking image quality may be the difference between gaining or losing a customer Which one would you choose? Which one will your customer choose?

42 Conclusion Objective print quality analysis Provides quantitative, repeatable print quality data objective vs. subjective testing Saves time during inspection Supports internal measurement standardization Using objective print quality analysis you can Benchmark against competitors Gather cartridge yield and performance data and statistical analysis in production Assess impact of formulation or vendor changes on product quality

43 Thank you! Please drop by the ImageXpert booth #1709 for more information and goodies!

44 Contact Information: imagexpert

45 Demo of ImageXpert s handheld unit Please feel free to share any samples you may have