Stochastic vs. Conventional Screening

Being in the printing industry and scrutinizing the printing on sheets of paper for over a decade comes with some side effects. I can't look at any printed piece anywhere without noticing the quality of print job. Some things were so atrocious (to me) I wasn't sure how they made it out of the print shop's door: I've seen food labels missing the yellow from the image completely, book covers embossed out of register (so far out of register that I was dubious that they were really even aiming for the cover, but the person with me said, "What? I don't see anything wrong." Sigh.), double or upside-down signatures in books, print artifacts (hickies) so large that they blot out portions of the text, and calenders with a coating on it that won't accept ball point pen.

But recently I noticed a new side effect. I went shopping for tile for my bathroom remodel. Did you know that the ceramic tile made to look like stone is printed? I didn't. But on the display shelf in the store, there was a piece of tile that made me do a double-take. "Wait a minute!" I said, "This tile is completely out of register!" I wasn't even looking that closely. But after seeing that, you can believe I did. And after looking at ceramic tile for a couple of hours I knew that the conventional screening pattern in the tile, whether in register or not, would drive me crazy every single time I took a shower. There were no stochastic screened tiles at all!

You see, I am not used to seeing a pattern at all in the printing I work with. Lorraine Press uses stochastic screening in all of its offset printing, and I am converted to the benefits of stochastic screening over conventional. I don't like seeing a pattern of dots making up the images. After working with the tiny micron-sized spots of stochastic, the dots used in conventional screening seem large and extremely distracting to me. And there was no way I could look at that tile and not see the conventional pattern every time I washed my hair. (But my tile saga has a happy ending, I ended up with natural stone tile, and it's gorgeous!)

For me, this experience just highlighted the differences between stochastic screening techniques and conventional screening techniques. There has been much debate about the benefits and difficulties associated with stochastic screening technology–more appropriately termed Frequency Modulated, or FM screening. A great deal of information is available from all kinds of sources, some correct and well-researched and some very incorrect. The information here, in this blog post, comes from Lorraine Press's own experiences through our eighteen years of printing using stochastic screening.

When starting out, some people told us that stochastic screening had limited benefits and was too difficult to work with to be useful. But after careful investigation and testing, we chose to use only stochastic screening, and since then we've never looked back.

Though there was a small learning curve when we began using this technology, we already had the quality controls in place that guaranteed our printing and proofing processes would be able to reproduce stochastic screening. And in the eighteen years since implementing stochastic, we have not experienced any problem that would undermine the many benefits that this technology provides. Lorraine Press has always emphasized high quality results, and our expertise in stochastic printing gives our customers just one more reason to print with us.

What exactly is stochastic, or FM, screening and how is it different from conventional screening methods?

Simply put, stochastic screening creates the illusion of highlights and shadows with extremely tiny, randomly placed spots. More spots create shadows, fewer create highlights. The "random" nature of the spots eliminates the possibility of moiré and other conventional screening artifacts. And the small size of the spots allows greater detail in the reproduction of images and an appearance closer to the original continuous tone image. Conventional screening creates the illusion of highlight and shadow by altering the size of uniformly spaced dots, larger dots for shadow areas, and smaller dots for highlight areas. These dots, because of their uniformity, can create artifacts in printing.

Here is one of our sample images we've printed using both stochastic and conventional screening techniques.

And below are side-by-side comparisons of that same test image, viewed under a microscope, printed in the stochastic screening which we use at Lorraine Press and in the conventional screening technology that has been used in offset printing for many years. Stochastic is on the left, conventional is on the right.

Here is a sample of four-color screened type, left side being stochastic, and the right side conventional screening:

These photographs demonstrate the superior results achieved at Lorraine Press with stochastic screening. However, in our experience, most people don't look at our printed pieces under a loupe or microscope. But when handed two samples of the same product on the same paper but one is printed in stochastic and one in conventional and asked which one they liked better, invariably people chose the stochastic sample. So all those microscopic details shown above may not be what your end-user sees, but those details and clean lines add up to a finer quality product overall, and they will see that.

Here is a list of some other benefits of stochastic screening:

• four-color process simulations of spot colors have the appearance and texture of an actual spot color and don't have visible screen patterns like they do in conventional,
• gradients can be reproduced with smoother transitions from light to dark without hue shifts and the lightest shades of the gradient print,
• fine type and curved or angled lines don't have stair-stepping, and lines remain the same width regardless of the angle they are set at,
• reversing type from screened areas is cleaner and shows more detail especially with a delicate serif font, 
• shadows contain more detail in the darker areas,
• more details overall in photos even under a loupe or microscope, creating a more photo-realistic appearance,
• subject moiré issues and visible rosette issues are nonexistent,
• less ink is used to print on the page, therefore stochastic is more "green,"
• inkjet proofing also uses stochastic, so there are no surprises on press due to screening difficulties.

In summary, stochastic screening at Lorraine Press provides a more photo-realistic reproduction of continuous tone images, smoother screen builds, and sharper fine line and type simulations, while eliminating subject moiré and other objectionable artifacts. If you would like additional information on stochastic screening, or to see more samples printed in stochastic, feel free to contact us at Lorraine Press.