HP Latex white ink workflow - How to use choke

Choke is used to shrink the white layer if there is a misalignment between the color layer and the white layer in the printed output when using Underflood or Overflood modes. Here are some examples:

Choke from the IPS in R Series

Using the IPS: There is new functionality in the Job Properties panel that allows choke to be applied.

The options for choke, at this point, are detailed in the following two sections:

1. Choke white ink

• If disabled (default), choke is not applied, and the white layer is not shrunk. It is maintained as in the original image.
• If enabled, choke will be applied, and some pixels will be removed from the white layer. The remaining choke settings will need to be defined.

2. Smart choke

• If disabled (default), choke will be applied to the full white layer. NOTE: Using this option, small text and details might disappear.
• If enabled, choke will only be applied in the areas of the image where there is color over/under the white layer. It will not be applied if only white is present. In addition, small text and details will be protected and will not disappear from the image.

HP recommends starting with 4 pixels (600 dpi) and then adjusting if necessary.

NOTE: The final area removed from the white layer is relative to the image resolution. Example: 2 pixels at 300 dpi is equivalent to 4 pixels at 600 dpi.

Choke from the RIP in Latex 700W and 800W

In Latex 700W and 800W printers, choke is set from the RIP. HP recommends starting with 3 pixels. If needed, it can be modified as follows:

1. SAI

2. Caldera

3. Onyx

Comments and considerations

• High opacity white print modes might require greater shrinking than fast white print modes.

Example: W260 (right) and W60 (left) with the same number of pixels choked.

• It is possible that choke may work very well in some areas of the plot, but that the misalignment is not completely removed in other areas.

Contributing factors to this:

• Quality of the printhead alignment.
• Media deformation.
• Print mode used.

Here you can access the full White Ink Workflow Guide for the HP Latex 700W, 800W, and R Series Printers.