The magazine of the Melbourne PC User Group Borderless Printing - for the bookshelf Mery Leeding

Back in the old days of typewriting, and more recently with dot matrix printers, it was possible to print right to the edge of the right and left sides of the paper. Typically, depending on the particular rollers, it was less easy to print right to the top and bottom of the sheet unless continuous paper was used in the dot matrix.

Laser and ink jet printers changed all that, introducing "unprintable margin areas" which differed from printer to printer. This was not always a physical limitation. Early HP lasers would not print within 0.5 inch of the paper edges. At first they tried to tell me the laser engine needed that margin to safely feed the paper. When I pointed out that I had replaced the electronics in two HP LaserJet (I) models with PSJet PostScript and an Impact Systems boards and now could print to about 4mm from the edges, they admitted it was actually a design limitation those chose to build into the firmware, believing that office users would not need to go closer to the edges.

Programs have different ways of handling situations where users set page margins in their documents that are inside the non-printable areas of conventional inkjets. Microsoft Word warns the user that parts may not print but allows the user to proceed if they wish. MyFamily's Family Tree Maker genealogy program over-rides the user settings in Print Setup and forces resetting of the page margins to the maximum printable area. Some programs give no warnings and leave it up to the user.

With the more recent wide-spread use of colour inkjet printers for photographs the user demand led to printer models offering "borderless printing". 1 use quotes because all was not quite as expected. It is interesting to note in passing that in more than a century of photography, preference for bordered (usually white) and borderless has tended to alternate.

How "Borderless" Works

The author's Epson Stylus PHOTO R210 has a print dialog "Borderless" check box which by default is not selected. In that default mode there are 3 mm unprintable margins on all four sides of an A4 sheet.

Now a user might imagine that if "borderless" is selected, the areas of the program's document within those 3 mm margins will now print. The user may accordingly set zero margins in the program and assume that the whole A4 page is available for the layout and therefore for printing.

This is not the way it works. Or at least Epson and other printer manufacturers have decided that it is not going to work that way.

What the printer does is take the "normal printable area" inside the 3 mm margins, enlarge it by a few percent, and print that stretched page right to the edges of the A4 sheet. Without the user being alerted in any way their carefully planned layout has been enlarged. This is illustrated in Figure 1 with the margins exaggerated to show the effect.

I found this anomaly while printing an A4 set of photographic montages for a 90-year birthday celebration.

How Much Enlargement?

To extend the normal printable width of 204 mm (210 less 2 x 3 mm) to the 210 mm width of A4 is a 2.86 % enlargement. This would be the bare minimum and would require the printer to have a very precise paper handling mechanism for correct registration. In fact test printing and measurement of a vertical line on a page with and without "borderless" selected, showed that the enlargement was 3.2 %. Thus a nominal A4 layout of 210 x 297mm is stretched to 216.7 x 306.5 mm.

The Epson R310 model is essentially the same printer with enhancements for digital cameras and would show the same enlargement.

Why Is It So?

(With apologies to that Professor.) I have found no explanation from Epson but looking at commercial printing provides a clue. Where it is desired to print to the edge of the paper the usual commercial practice is to combine the use of oversize paper cut to size after printing, with "bleeds", a technique where the original layout provides for coloured areas and image to go outside the dimensions of the final page.

Now home and office printers are limited precision when it comes to paper handling and oversize paper is not usually an option. There is also insufficient precision to print just to the paper edges since to avoid paper jams there is usually often a little extra space on both sides of the paper in the tray. This can be up to around 0.5 mm total and earlier low-cost models might exceed this. Clearly even a small 0.1 or 0.2 mm misalignment of the paper could leave a sliver of white along the edges of the paper.

If the printer driver enlarges the image beyond the set paper size and the print head works in conjunction with this to print a little wider than the page as well as starting and finishing just outside the vertical dimensions of the sheet, a true borderless print can be guaranteed.

Overspray

However, one puzzling issue remains. If over-printing is the only way to ensure a borderless print, what happens to the ink that of necessity is thrown outside the paper area? Does it build up on rollers? Is there a mechanism for cleaning this without user intervention?

I have printed relatively few borderless prints and it is not easy to see inside the printer so at this stage those questions remain unanswered.

Canon Printers

At least one Canon printer also shows this enlargement effect though it was less at 2.5%.

Family Tree Maker

I mentioned above that this popular genealogy program tends to over-ride user settings which it judges to be unsatisfactory. It does however take the borderless setting at face value and accepts zero settings for the margins. This is useful, at least in theory, since creating family history charts has always been a battle to fit the content within a minimum number of pages. For home-produced A4 books the goal is often to achieve one-page charts.

When Family Tree Maker accepts zero margins and designs for them, borderless printing can mean bringing the design closer to the edges than intended, or at worst, clipping of the design at the edges. This is not a hypothetical situation since every bit of extra width helps when laying out family history charts.

Maintaining Image Size

A search of the Internet produced a reference to this unexpected printer behaviour. One user said he routinely reduces the size of his photos by 2.5 % before printing when planning to print borderless. One minor problem is that the re-sampling in that 2.5% reduction produces a small quality loss followed by another resampling when the printer enlarges the image. In practice the difference will be small and with the move to digital cameras there is often no conventional print for comparison.

Manufacturing Alternatives

How else could Epson have ensured that borderless photographs were free of any white borders at the edges?

Epson could have left the printer operating in borderless mode as it does now, eliminated the 3.2 % enlargement, and let the author of the document handle this by bleeds as the professional does. Such bleeds would need to be very small but the printer driver could "cut" them back to keep within the target area of the inkjet nozzles. It would also require that the user's software be able to handle bleeds this might be the biggest problem.

Some of those early laser printers with artificial margin limits could be fooled into printing into the margin area by using A4 in a US letter tray. That would often add a quarter inch to the printing width. Many laser printers would report the incorrect size tray but offered a "Continue" option.

In Summary

Most users will simply ignore the effect particularly those printing single photographs. Those working with more complex layouts need at least to be on the aware of the possibility of compromised designs. One option would be to set a custom page that is 6 mm narrower in both dimensions for A4 so that the ultimate printed area can be seen as the "page" in the word processor or layout program.

Reprinted from the Jan / Feb 2006 issue of PC Update, the magazine of Melbourne PC User Group, Australia

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