Offset vs. flexo image adjustments

[pp411]

I am familiar with the offset world but transitioning to flexo. We rarely have to adjust images. How do flexo prepress operators handle image editing? Is it a manual process where the minimum dot (and abrupt transitions) is adjusted in Photoshop, or are plugins such as Esko's flex tools used? Same thing for stray dots? Or are you still laughing because I don't know what I'm asking?

 

[gordo]

I am familiar with the offset world but transitioning to flexo. We rarely have to adjust images. How do flexo prepress operators handle image editing? Is it a manual process where the minimum dot (and abrupt transitions) is adjusted in Photoshop, or are plugins such as Esko's flex tools used? Same thing for stray dots? Or are you still laughing because I don't know what I'm asking?

IMHO, given the advances in flexo platemaking and halftone screening I think that shops that are using those technologies can rival offset. So, I guess the answer is that it is shop dependent.

 

[mjetzer]

Depends on the shop and the tools they have. We use a combination of stuff. Stray dots and minimum dots can usually be handled with the Flexo Plate (bump) curves that move everything from 1% up to the needed Min Dot. The workflow will most likely have a function to remove anything below 1%. We find that images often need to be adjusted in Photoshop to get rid of contaminating color, example removing the Cyan from a photo of Bacon and replacing it with black. On a flexo press, those contaminating colors can be very obvious - Cyan in Reds, Magenta in Greens. You will also find that it's common to run more line colors and avoid converting to 4/c process. Gordo is correct that Kodak NX and the ESKO HD Flexo are making flexo rival offset in many ways reducing the need for the image adjustments.

 

[pp411]

Great summary, thank you. I am, however, still curious how you determine which colors will contaminate. Is it more experience of the operator? Do you view the Photoshop file with the ICC profile of the press in order to see how they appear?

 

[Stephen Marsh]

Great summary, thank you. I am, however, still curious how you determine which colors will contaminate. Is it more experience of the operator? Do you view the Photoshop file with the ICC profile of the press in order to see how they appear?

I believe that this is a GCR decision, as well as operator experience. Red is M+Y, so C contaminates and can be reduced or totally replaced with K. Green is C+Y - so remove/reduce M, Blue is C+M, so reduce/remove Y. As it can be common to swap out process colours for spots, you may find that there is no magenta/yellow and the job is simply using a spot red instead (or no black and one is using a dark blue). You will probably find channel mixer and apply image commands helpful for this task.

It has been a while since I was in flexo prepress production, so I hesitate to offer the attached Photoshop action… There is no warranty or guarantee, use at your own risk (I of course welcome feedback, both positive and negative).


Stephen Marsh

 

[pp411]

I finally had a chance to play around with these. Thank you! I think these are useful. I'm not very familiar with GCR, so I'll have to investigate that.