"The challenge isn't just to be fast enough", says Global Graphics' chief technology officer, Martin Bailey. "The real challenge is to achieve that goal without incurring an uneconomically high cost for the bill of materials to build the Digital Front End."
* Digital Front Ends (DFE) Face Rapidly Increasing Data Processing Requirements as Print Jobs become More Complex
- Increased Use of Transparency
- Need for Increased Variable Data Coverage
* Race for Speed is On-going Competitive Challenge
- DFE Must Process Data Quickly Enough to Drive Press at Full Rated Speed
- Press Manufacturers want to Minimize DFE Costs Vs. Cost of Press
- Must Respond to Market Needs & Opportunities: Photobooks, Personalized Marketing Materials, etc.
* The Holy Trinity
- Speed, Quality & Reliability
* Once the Hardware is Optimized - What Then?
This presentation was delivered to the IMI 19th Ink Jet Printing conference on 9 November 2011.
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 Press3
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 Indigo 7500 Digital Press HP T400 Color Inkjet Web Press6
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 efficiency20
PARALLELISM – WITHIN A MACHINE We invest effort to take advantage of all of these machine-level parallelisms: – 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 RIP21
PARALLELISM – END-TO-END SOLUTION Split into page ranges RIPs deliver data in parallel Press controllers and assign to RIPs to press controllers deliver to presses Split files into multiple “partitions” or chunks and process in parallel Parallelize early, maintain multiple parallel pipelines Parallelize in pre-RIP, where the data is much smaller (1/7th the size) Process multiple jobs in parallel Different variations optimize first-page-out, engine loading or throughput22