HybridScreen - Hybrid screening technology

HybridScreen combines the benefits of AM (Amplitude Modulated) screening in the midtones and FM screening in the highlights and shadows.

Click to view full size Shadows and Highlights Screening
Shadows and Highlights

FM dots are distributed in a dispersed pattern in a subset of the positions where AM dots will later appear.

Click to view full size Gradient Screening
Gradient


Higher screen frequencies can be used than otherwise possible. Without the FM highlights there would be a sudden transition when the smallest stable dot appears in each halftone cell, and this transition become a bigger tone jump with higher frequency. With FM, the fraction of those cells are finely controlled in the extreme highlights, allowing for a smooth transition.


Click to view full size Screening the face
Screening the face

Click to view full size Screening the blast
Screening the blast


The technology is explained in more detail in U.S. Pat. No. 5,766,807 and US Patent Application 20030107768.

This technology is licensed from Monotype Imaging and is similar to the Agfa Sublima technology.

Hybrid Screening is a solution to the "highlight break" of flexography printing? The excessive highlight gain and minimum dot "requirements" - caused by the nature of small dots on flexo plates to "squash" and become bigger - have long been considered an insurmountable obstacle in the path of high-quality flexography printing. Some have tried stochastic screening to combat this problem, while it does improve the highlight break problem it creates new problems - excessive dot gain, grainy reproduction.

Hybrid Screening combines the best of stochastic and traditional screening by creating a smooth transition between stochastic highlight dots and conventional screening through the rest of the print range. You can now print highlights which truly fade to zero, and have precise control over subtle pastels and shadings previously nearly impossible to achieve in print production.

HybridScreen is a Cross Modulated "XM" screening technology that uses the industry proven Agfa Balanced Screening "ABS" AM halftoning in the midtones and smoothly transitions to a modulated FM dispersion based on the "AM" angle and the minimum dot size in the highlights and shadows.

HybridScreen reduces the need for bump curves and cutback curves typically used to address the deformation problem in highlights followed by the dot gain in midtones. With HybridScreen it is possible to improve print quality on full tone printing without special curves, thus saving time and money!

Research Screening Technologies:

This link references a study done on flexo printing using various screening technologies: research screening technologies

New! HybridScreen in Lucid Products:

Lucid has implemented HybridScreen Technology (HST) as a new dot structure in the normal Dot Shape selector of our I-Tone and TIFF/ITflowproduct lines. Now instead of Round and Elliptical you will see HSTRound and HSTElliptical. This the currently the only internal change.

Externally HST will be delivered to beta sites as new "SCREEN.HTD" files specially made for your purposes.

The HST SCREEN.HTD files contain screen settings for these values:

  Value Contained in Sample Set
1. Print Type Flexo, Traditional
2. Dot Shape Flexo-HSTRound, Trad-HSTRound and HSTElliptical
3. Resolution 2032, 2400, 2540
4. LPI 150, 175, 200, 225, and 250
5. Min Dot Size 1, 4, 7, and 9 pixels
If you need screen sets other than these then please send your request to support@luciddream.com. Please indicate the needed values for items 1-5 above.

The sample screen sets are delivered as an archive which extracts to a folder structure by Print Type followed by Min Dot Size. Inside each folder is a specific "SCREEN.HTD" file for that set with the various dot shape, resolution, and LPI options.

To use these files you must first decide which print type you use, conventional offset (Traditional) or Flexo.
Next you need to determine what is the smallest dot that your printing system reliably supports. This is the more difficult part but there are several methods;

1. Output our special test file and then print this file and determine what dot size is most stable.

2. Print a smooth gradient at a very high lpi and then use a high power magnifier to locate the point at which the dot retention becomes unreliable and count the pixels in the most stable starting point.

To output the special test file please download the file from here.

This file needs to output without any scaling this is very important. If you have any questions about this then please give us a call.

The base file is 8.5 width by 11 height at 2540 DPI. If your system is a different resolution then open this file first in Photoshop and select the image size option and change the resolution value. It should then change the size of the file dimensions. This is the proper way - DO NOT SELECT THE OPTION "RESAMPLE IMAGE"!

Then save the new file under an informative name and output this file.

For best possible results you should actually print this job on your press. This will give you the best information about what is the minimum dot size that your entire printing system can properly hold.

Review the printed sheet and evaluate which test patch has the most stable smallest dot pattern. Once you have determined this value then please contact us with this information so that we can make sure you have the proper screen set for your testing.

Getting Started:

First please determine if the sample set described above will meet your needs, if not then you should start by requesting a new screen set with the values you indicate.

Screen sets are delivered by FTP from this location.
Download the appropriate zip archive of the screen set - for instance the beta set is named:
HST-2032-2400-2540by150-175-200-225-250.zip

Extract this file to your local drive where either TIFF/ITflow or I-Trap with I-Tone is installed.

Next please search your machine for the existing file named "SCREEN.HTD", it will be 200+ meg in size and carefully move this file to a safe location but keeping track of where the original location was. Another option is to just rename the original file to something like "SCREEN.HTD.ORIGINAL". Please do not let this file get deleted as you will need it for non-HST print jobs.

Next select the appropriate print type and min pixel size folder in the HST archive and copy the SCREEN.HTD file from this folder to the original location.

Now start the application either TIFF/ITflow or I-Tone and bring up the screening control.

For each ink you should select either HSTElliptical or HSTRound as the dot shape and the appropriate LPI.

You are now ready to output files and print jobs.

More Benefits:

There are a number of benefits to using this type of screening most of which fall around the idea that for various reasons very small dot shapes are not reliably reproduced. Therefore tone values in both highlight and shadow areas are lost. To compensate for this problem using normal screening a low LPI value is used to keep a large minimum dot size.

Using HybridScreen Technology the minimum dot size is predetermined. Therefore it is now possible to use significantly high LPI - thereby giving much higher quality printing - and not have to worry about losing detail and tone in the end points. Once the dot size reaches the minimum size then further tone values are achieved by removing dots rather than removing pixels from dots.

XM technology applies a common sense approach to screening; match the screening to the pressroom environment, rather than changing the pressroom to match the screening requirements. HybridScreen takes into consideration the type of paper typically used, such as coated, uncoated, or recycled; the printing architecture, such as flexography; and other variables. HybridScreen works within the established parameters and uses the smallest optimized and printable dot for the application.

FM screening tends to produce grainy looking results with flat tints and process-build brand colors. The regular orthogonal AM grid of HybridScreen gives a smoother appearance than grainy FM. Even more so is the case for flesh tones, not only does the AM grid produce smoother more appealing look, but the XM highlights holds all of the tonal values - right down to the twinkle of the eye!

HybridScreen is more forgiving on press than typical FM screening and it is much easier to control gray balance. HybridScreen matches your press by first measuring your press/paper capabilities and then matching those capabilities to the dot.

Using XM screening newspapers can attain 180 lpi, sheet-fed printers can use rulings of 200, 225, 240, even up to 340 or higher, and flexo printers can approach 200 or more.

HybridScreen adds value to print because accurate screening at the highest possible lpi results in a visibly better printed result, thus differentiating a printing company from its competitors and opening the doors to new business opportunities. HybridScreen also saves money by virtue of better reliability, longer print runs, better color control, and lower dot gain. HybridScreen also saves time and money in ability to easily switch between standard ABS screening and HybridScreen without the significant press and press operations changes required when using FM.


Additional benefits and features of Hybrid Screening can be found in this article.