Load balancing and nesting

As a GMG ColorProof administrator, you have full control over each step of the complete process by defining workflow parameters. The smart logic behind the software allows you to combine load balancing together with nesting strategies. This way, you can use the full capacity of all your printers while saving media by combining "compatible" images to a single job. It might take a while to optimize the system for your printer pool and internal workflow, but once set up, you will greatly benefit from the high degree of automation.

The following illustration will give you an idea of how load balancing and nesting works in GMG ColorProof. The following information will describe the behavior in more detail.

Load balancing and nesting.

In this example, three workflows (A, B, and C) are set up to process images according to different proof standards. (For load balancing and nesting, it does not matter which workflow is linked to which hotfolder and which file filters are used for each workflow.)

One image is processed by each workflow (for example, by separate hotfolders or different file filter settings). Each workflow processes its image in a different way according to the workflow parameters, for example, using different proof standards. To give a specific example: if tagged with different ICC profiles, the three images would be identified by the Embedded ICC Profile filters defined in the workflow.

After color-managing the images, the software distributes them among the printers in the printer pool (load balancing). Two of the three images use the same nesting strategy (template 1, > 60 % image-filled space) and also have compatible printer settings (for example, both proof standards support the loaded medium GMG ProofPaper semimatte 250). These two images will be collected into the same job. The job will remain in Nesting state (in the Jobs view) until 60 % of the defined roll length is filled; with 60% filled, the job will be printed.

The image in workflow C uses a different nesting strategy (template 2). It is sent to a different printer from the pool, centered horizontally on the printer medium, and printed directly as a single image.

In the Manual Job Manager, you can directly define a job with multiple images and different proof standards. Idle printers can be manually selected from the list of available printers.

In a workflow, you view a similar list of available printers and supported media for the specific workflow settings on the Load Balancing and Nesting page. You can select the printer medium to be used for all jobs generated by this workflow and you can select the printers for load balancing.

Load balancing automatically assigns a new image in the linked hotfolder to an idle printer from the printer pool. The smart load balancing algorithm also takes the image sizes and the media sizes supported by the different printers from the pool into account. It picks the printer that either directly supports the image size without resizing the image or that requires the smallest change of the image size (if Image Processing rules have been defined by the user). If no printer in the printer pool supports the image size (after Image Processing is applied), an error job will be created that can be manually edited in the Jobs view and then sent to the printer.

When an image is placed into a hotfolder, it is immediately sent to an idle printer provided that the following requirements are met:

• The printer assigned to the job is part of the printer pool for this workflow.
• All printer settings (loaded medium, print mode) match the workflow settings.
• The image size fits onto the media size or there is no other printer available requiring less changes of the image size (Image Processing).

A job is created and appears in the job list. If no printer in the printer pool supports the image size (after Image Processing is applied), an error job assigned to the largest format printer is created and can be manually edited in the Jobs view and sent to the printer again.

Available printer-medium combinations
In the Workflow dialog box > Color Management > Proof Output page, all available printers and media compatible with the selected proof standard are listed. Only printers and media listed here will also be shown on the Load Balancing and Nesting page. If you want to use a specific printer–medium combination not shown on the Load Balancing and Nesting page, check whether you have defined a proof standard for the combination.

Nesting makes the situation a little bit more complicated, but also greatly enhances the automation capabilities of the program. Let us start with a basic situation—nesting without load balancing, that is, with only one printer in your printer pool.

Nesting allows you to automatically create jobs with multiple images, just as you would manually create jobs in the Manual Job Manager. This saves valuable proof media and can simplify your internal workflows, for example, if you collect all images for a certain client or for a certain print standard, printing them in a single job.

Every Nesting Template contains a set of nesting rules (a so-called nesting strategy). Several predefined nesting templates for common tasks are already provided by GMG GmbH & Co. KG, but you can also set up custom templates to fit your needs. For example, you can use a nesting rule requiring 60% of a defined roll length to be filled with images before printing. For the digital print production of photographic images with PhotoProof profiles, you could use a nesting rule requiring all images to be automatically centered, rotated to Portrait orientation, and printed as single images.

You can collect images across multiple hotfolders and workflows. The Nesting page in the Workflows view provides you with an overview of all nesting strategies currently used by your system. It shows which workflows and printers participate in which nesting strategy.

If load balancing and nesting are used in combination, GMG ColorProof looks for an idle printer first (load balancing) as soon as the first image is recognized in the linked hotfolder. The program checks whether the image size fits onto the medium size, and whether all other printer settings (loaded medium, print mode) are compatible with the workflow parameters according to the rules explained above.

A job in the status Nesting is created and appears in the job list. If multiple images with compatible print settings are in the hotfolder at the same time, the images are distributed on the sheet or roll for minimized media usage.

If a new image is placed into the hotfolder, it will be added to an already existing job in status Nesting provided that all requirements for load balancing (see above) are met. An new optimized image placement on the sheet or roll (to reduce media costs) is computed each time a new image is added to a Nesting job.

If one of the requirements is not met, a new job in status Nesting (assigned to another printer from the pool) will be created. If no printer in the printer pool supports the image size (after Image Processing is applied), an error job assigned to the largest format printer will be created.

Putting finished jobs automatically on hold after nesting:
Activating the option Hold Finished Jobs, jobs created by a nesting template are automatically put on hold after the finishing rule defined in the nesting template is met.

This feature is very convenient if you want to check the final job in the Manual Job Manager before printing. Alternatively, you can use the Image Preview for PDF/PS files, as PDF/PS files are automatically put on hold after being ripped.