RIPping through data - Challenges faced in the digital front end

© Copyright 2011 Global Graphics Software Limited 1

Martin BaileyCTO, Global Graphics

RIPping through dataChallenges faced in the digital front

end


– This presentation was created with assistance from our partners at Hewlett Packard.

– Especial thanks are due to Dave Staas, Lead Software Architect, Indigo Digital Press DFE

ACKNOWLEDGEMENTS

3

INTRODUCTION

– A Controller or Digital Front End (DFE) provides a number of functions for digital press print jobs:• Workflow definition, control, and management

• Job management (submission, status, view, edit, cancel, etc.)

• Color, ink, and media management

• Imposition and finishing management and control

• The conversion of rich document formats like PDF and PPML into “print ready bits” – data that is rendered and formatted for the marking engine of the digital press

HP Indigo W7200 Digital Press


CONSTRUCTING A DFE

Control process

RIP

RIP

RIPPress

controller

Pre-processin

g

Post-processin

g

HP Indigo 7500Digital Press

Job cache

Raster cache


WORK ALLOCATION

– Interpreting/rendering –

– Color management –

– Imposition – , or

– Trapping – or

– Screening – or

– Font handling –

– Variable data –

– + for PPML etc for PDF with no h/w assist + for PDF with h/w (+) or (++) for PDF/VT

Control process

RIP

RIP

RIP

Press

controller

Pre-

processing

Post-

processing

Raster cache

Job cache

6

WHAT’S THE PROBLEM?– A typical print shop can have many digital presses and DFEs (Consolidated

Graphics, for example, has more than 50 Indigo digital presses across several sites1)

– A standard mid-range digital press (120 PPM) requires the processing of over

one hundred million pixels every second, worst-case, with possibly multiple transforms, and in 4 (or more) colors

– HP’s high-end presses (like the T400 below) require around three billion pixels every second

– The primary performance goal for a DFE is to process any job or workflow at or above press speed – strive to always have the DFE outpace the press over a shift

– Maximum efficiency must be exploited in every aspect of the system’s design in order to achieve this goal within reasonable cost constraints

HP T400 Color Inkjet Web PressHP Indigo 7500 Digital Press


Example 1: cut-sheet, 800x800dpi, four color (CMYK), 8 bits per pixel per colorant, 120ppm (A4), single-sided• 800 x 800 = 640,000 pixels per square inch• 640,000 x 11.69 x 8.27 = 61,872,832 pixels per A4 page• 61,872,832 x 120 / 60 = 123,745,664 pixels per second• 123,745,664 x 4 x 8 / 8 = 494,982,656 bytes per second• = 472 MB/s

Example 2: roll-fed, 600x600dpi, four color (CMYK), 8 bits per pixel per colorant, 41.75” printable width, 600 ft per minute, two-sided• 600 x 600 = 360,000 pixels per square inch• 360,000 x 41.75 x 600 x 12 = 108,216,000,000 pixels per minute, per side• 108,216,000,000 / 60 x 2 = 3,607,200,000 pixels per second, duplexed• 3,607,200,000 x 4 x 8 / 8 = 14,428,800,000 bytes per second• = 13.4 GB/s

THOSE CALCULATIONS …


– Speed: pages per minute (usually A4 or US letter equivalent) •Defines max throughput while the press is running• Important for office print and light production

– “Duty cycle” has different meanings for different sectors:•Office and light production:

−Simplistic calculation of how many pages a printer could produce in a month running flat-out for 1 shift per day

−Not representative of any realistic throughput

•High-volume production−The vendor’s assessment of a realistically achievable page

volume per month for that press−The number of pages a print company expects to be able to

produce every month from their press

SPEED VS DUTY CYCLE


– the monthly duty cycle of a given product is not the “recommended” volume at which it should be used on a consistent basis.

− Paul Albano, Canon USA

– Most vendors of document imaging devices specify a “monthly duty cycle” for their products […]. This number represents the maximum number of pages a product can produce in a month. It is not the volume at which the product should be used on a regular basis. […] In the real world, products are being used for much lower volumes, ranging from 5 percent to 20 percent of the duty cycle in the case of monochrome products.

− Buyers’ Lab

– This is not true for high-volume production. Print service providers expect to achieve the duty cycle every month to ensure that they can meet planned return on investment.

IN LIGHT PRODUCTION …


SPEED & DUTY CYCLE

60 70 80 90 100 110 120 130 1400

1

2

3

4

5

6

7

Duty cycle (Mpp/m)8/516/624/7

Speed (ppm)

Duty

cycle

(M

pp/m

on)

• Speed plotted against duty cycle for a number of high-volume digital presses.

• Diagonal lines show the page volume achievable in 1, 2 or 3 shifts at that rated speed.


HOURS PER DAY TO REACH DUTY CYCLE

60 70 80 90 100 110 120 130 1400

2

4

6

8

10

12

14

16

18

20

Speed (ppm)

Hours

per

day r

equir

ed t

o a

chie

ve r

ate

d d

uty

cycle

• The same data, now showing hours per day required to achieve duty cycle (7 day week).

• High numbers imply an expectation that the press can run at rated engine speed for most of every shift.

• Planned maintenance is not taken into account.

• This duty cycle range selected to illustrate cross-over from light-production to high-volume production expectations


–Print service providers in high-volume digital production print expect to achieve duty cycle every month

–This requires that the press run at rated engine speed almost 100% of the time, regardless of job content or complexity•Except for planned maintenance periods


All this talk of hugely high performance requirements … do I still have to worry?

It’s solved for current jobs and current presses, but:

– New presses need higher data rates• Larger format/wider webs

•Higher paper speeds/pages per minute

•Higher resolution (2x resolution = 4x raster size)

•More colorants (MICR, photoink, HiFi, spot colors etc)

•Multi-bit screening

• And …

IT’S A SOLVED PROBLEM, ISN’T IT?


– Larger coverage of variable data in direct marketing, triggered by• Better demographic data• Better data mining techniques• Proven better response rates to well-crafted personalized mail

– More use of live transparency• Driving adoption of PDF for direct marketing• Expanding out of general design practice for books, publication, POD, print-for-pay and general commercial print• Many designers don’t even know they’re using transparency!

– In a well-optimized RIP transparency requires more processing than an opaque job• Color transforms & read/modify/write cycles

JOBS ARE GETTING MORE COMPLEX


THIS IS TRANSPARENCY …


AND THIS …


AND THIS


– PDF/VT (ISO 16612-2) defines structures in a PDF file to:• Allow easier identification of re-used and single-use graphical elements

• Define which sets of pages go together in a hierarchical structure− E.g. as components that will be supplied to a single direct mail recipient

• Enable pseudo-streaming

• Encourages good practice through PDF/X• All fonts embedded

• All colors formally defined etc

– This means that PDF/VT is a useful standard!

– But it does not address the fundamental issues of:• Compute power required to process transparency

• Sheer data volume required to drive current and future digital production presses

DOESN’T PDF/VT FIX THE PROBLEM?


– With the right architecture and components you can make a DFE drive your press at engine speed

– The key metric is the throughput achievable per € total bill of materials• Include hardware and software

• Every component makes a difference

– The target is to drive the press at rated speed while minimizing the cost of the DFE• If the software is faster or more efficient you can reduce the hardware required

– Reducing hardware reduces power consumption and cooling• Going green can be profitable!

THE REAL GOAL

20

ARCHITECTURAL CONSIDERATIONS

– Some of the more relevant architectural considerations for enabling maximum efficiency:• Reliability

− Fast, unreliable systems usually aren’t worth much. Stability first, performance second

• Work Avoidance− Look for ways to move or eliminate work first rather than scaling an inefficiency

• Centralized or Distributed Caching− Caching can avoid work and improve performance

− Watch for centralized caches becoming a bottleneck

• Instrumentation and Measurement− Establish a way to measure performance in your code and system

• Planning− An ounce of design effort up-front will save more than a pound in efficiency and cost-savings in

development and manufacturing

− If you drive a range of devices you may gain from a common, scalable solution across at least some of that range

– No universal right answer on most of these considerations; they’re useful topics to think about in the context of efficiency

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– Multiple CPUs per machine

– Multiple cores per CPU

– Multiple physical disks per machine

– Multiple physical disks per logical disk

– Multiple (teamed/bonded) network interfaces per logical network connection

– Multiple RIPs per machine

– Multiple threads per RIP

PARALLELISM – WITHIN A MACHINE

We invest effort to take advantage of all of these machine-level parallelisms:

22

Split into page ranges and assign

to RIPs

RIPs deliver data in parallel to press

controllers

Press controllers deliver to presses

PARALLELISM – END-TO-END SOLUTION

Split files into multiple “partitions” or chunks and process in parallelParallelize early, maintain multiple parallel pipelinesParallelize in pre-RIP, where the data is much smaller (1/7th the size)Process multiple jobs in parallelDifferent variations optimize first-page-out, engine loading or throughput


– Digital printing architectures need careful design

– Many different strategies must be employed in unison for the best effect

– Key architectural considerations can help guide your efforts

– Selection of the best components and supplier/partners is an important aspect

– The ultimate goal is to reduce cost, power, and cooling for customers

SUMMARY


Q&A

More information at www.globalgraphics.com/imiconf

Date post:	21-Aug-2015
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RIPping through data - Challenges faced in the digital front end

Technology