RIP film output - process linearisation

[willy35]

Hi,

I am about to buy Filmagate for film output, and wanted some input about the linearisation.

The reseller told me they only do it for the printer outpur, not with the printed shirt.

I wanted to know what are the good practice in the industry, just to make sure my reseller will do things well.

Thank you !

[Colin]

For many of us, we will adjust for dot gain in the separations/art room. 

We want our films to be as accurate as possible.  Then we go to screen and try to burn our screens as correctly as possible to minimize dot loss etc.

Then we look at what our dot gain is across the many variables of t shirt fabrics/sweat shirts or hoodies/white plate Vs direct on shirt/mesh selection/squeegee selection/ink type etc...  then go back to the art room and fine tune that process over the rest of our print careers

Best of luck!

[ABuffington]

The linearization of the film output is done in Filmgate (as well as other RIP programs) to produce accurate halftones using a densitometer to measure and input into the software to create a transfer curve.  Dot gain on shirt is all over the map depending on press settings. You can output a linearized film using the filmgate target, shoot an appropriate screen and print it to do a visual check of the gain.  Typically the second linearization would be done with a different densitometer on printed flat stock for a reflective reading. You can visually adjust and reduce values of greyscale in Photoshop to match back to the linearized film output for a DIY method, or some RIPS have a second press curve function that can be modified.  Mesh selection, thread type, tension, open area, Press settings, squeegee duro, sharpness, angle, speed, ink viscosity, ambient temps, so many things affect the gain on press that can cause dot gain as well. So the second press linearization is a moving target and documentation and standardization can still only get you so close, but the print can improve when you fine tune it over and over. In both cases you are creating transfer curves that take the original art and modify the values.  Adjusting curves is the magic behind linearization to produce prints with greater tonal values to get tones to print below 25% and above 75% to bring out more glow in the print. 1 for film, 1 for print, 2 curves needed for optimum print quality.  Add to this dot shape, sharpening in the original file, stochaistic dots, hybrid screens, the options to improve don't end with linearization.

[willy35]

I work like Colin describe, but in my shop it is not perfect.


Thank you for your valuable informations this will help me !

[domineight]

This reminds me I should be playing around with mine, although straight out the box filmgate worked well for me. It's a nice RIP, everything is pretty clear and easy to find and tweak, and produces nice tight film.

I have Colourgate filmgate 7, lite - Which is presumably because I have, or had, a small format Epson which seems to have come to the end of it's life according to the error code it's throwing up. Oddly, right before it decided it's life was over, it was running perfectly. Very annoying.

[willy35]

Good to hear.

I am still not sure which RIP we will choose.

Wasatch, filmmaker, filmgate, harlequin...

I post here answers I got, as I am looking for AM/FM - Hybrid stochastic screening, so it is easier to keep dot under 5% on garment.

Wasatch :
has it, a friend of mine run with this RIP.


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Filmgate :
We have a hybrid dot inside our software. We have the possibility to choose an area in the screening which should be FM like what you have described in your graphic.
We just do not publish this as a default since nearly every screen printer has some kind of standard and we need to precalculate these screenings. This would result in 100 of different presets.
Every screening except our Custom Screening are pre made bitmap files.
The reason behind this is we are using super cell technology to overcome the issues of inaccurate screenings which show up by using “non supercell” screenings.


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Harlequin RIP
Yes, our Epson RIP does have variable Stochastic Screening

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Filmmaker
Could you please explain more about advanced AM/FM screening algorithm ?
The answer is a bit more complicated, in short yes it is a hybrid as it does use a stochastic (FM) and halftone (AM screen) in the screening process but its not the same as other traditional hybrid screens, hybrid screens are normally pre calculated based on certain dpi output, LPI requirements and angles. Because most of our customer base are not traditional offset users and have a wide range of halftone output requirements we developed a system that would work with any traditional halftone setting (so you can set LPI, Angle and spot function) and then apply the stochastic part to this screen. So its very different from anything else currently available from other manufacturers.
What we do is apply the stochastic screen on top of the AM screen and you can select how much to apply anywhere in the tonal range, so you can choose to apply this just in the midtones or only in the highlights / shadows and what it will do is start to break up the regularity of the halftone, if I applied in high value it will start to look like a stochastic.

What kind of control do we have on the dots size in microns on the fm part ?
As the FM part is applied to the traditional AM, it is the AM that determines the dot size.

Who make the linearization if I get it ?
We include a generic linearization and you can do your own with a densitometer.