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Creating a Printer Template

By Mike Pasini
Editor, Imaging Resource Newsletter

No matter how many dots per inch your printer boasts, you'll want to feed it a certain number of pixels per inch. The optimum number, to be precise. More than that just eats up RAM and time. Less than that gets you lousy print quality.

"The trick to fitting your image to the template is to change the size of the original image."

But, let's face it, we didn't bring this up to polish up our math skills. There's an easier way. It's called a printer template.

Take for example our Nameless Inkjet printer. Please. [ghostly laughter] It boasts a resolution of 600 dpi (or what it euphemistically calls "addressable raster points per inch" and what we consider to be "spots"). It can lay down 600 spots an inch either direction. No less, no more (as a certain tombstone over Les Moore once had it).

Now consider our bevy of house digicams, some sporting experimental (at the time) CCDs of merely 640 x 480 pixels, others with 2,048 x 1,536 pixels and still more with their own unique dimensions.

The game is obviously to print the images captured by the CCD on the paper (preferably that nice glossy photo stuff that costs a fortune) using the Nameless Inkjet. But how do we get from 2,048 x 1,536 pixels to 600 dpi?

The template.

In your image editing program, create a new document the size of the sheet of paper you intend to run through your printer. That would be 8.5 x 11 inches for the Nameless.

Your printer manual may tell you the resolution to use. Take a look. Our dye sub insists on 203 pixels per inch in our image; others want 300 ppi. Our inkjet says it can print a halftone screen of 85 lines per inch. Which means (even though we are printing a special kind of screen) we need at least that many pixels and no more than 2.5 times that. So we test the same image at 85 pixels per inch up to 200 ppi (212.5 rounded down).

We chose an image of a face and printed it at various lesser resolutions until we lost quality. We inspected the eyes on each print (with a loupe or magnifying glass) for both detail and color to learn that the Nameless printed the same image at 150 as it did at 200 ppi but not as fine an image at 100 as at 150 ppi.

Make sure the color mode matches what your printer driver requires (printers are CMYK beasts, but their software drivers usually convert RGB data into CMYK). The Nameless wants RGB data. Make sure the document has just a single layer, if you are blessed with layers. And fill it with white (for ink jets, to save ink) or black (for dye subs to distribute the heat evenly).

"No matter how many dots per inch your printer boasts, you'll want to feed it a certain number of pixels per inch."

Next, use your Page Setup dialog to set orientation (we have two templates, one for landscape and one for portrait), paper type (that Glossy stuff is nice), ink coverage, and any color matching options you've found work best for you. Then just save the template as a JPEG (if that's your preferred format) or TIFF with a revealing name.

You now have an optimal printing template (a virtual sheet of paper) for your printer regardless of what spells your images cast.

To tap its powers, just copy your edited camera images onto the template to arrange it (either as an 8x10 or two 5x7's or whatever you like) so it uses as much of that expensive paper as possible. And print from the template, not the original image (which preserves your original data, too). Save the template with a new name if you want to make more copies of these images later.

The trick to fitting your image to the template is to change the size of the original image. Open any image and your image editing program maps the pixels wide and high to your screen: 72 [M] or 96 [W] an inch. But you're not printing to your screen. You're printing on paper, represented by your template.

Start by changing the width or height of your final crop to your final output size without resampling, making sure Constrain Proportions is on. If you want a 5x7, say, change the short dimension from however many inches it is to 5 inches. You'll see the pixels per inch jump up from 72 but the file size remain constant, if you did this right.

If your resolution exceeds your template's (150 in our case), resample down to the template's (and apply the Unsharp Mask filter). If it is less than that, you don't have enough resolution to print at that size. Make the image height or width smaller (quick tip: change the resolution to 150 dpi).

Don't save. Just copy the image data to your template and position it efficiently. When you've filled the sheet, print it.

Set up a template for each printer you have in both orientations and fit your images from any source (scans, too) to that template and you'll (magically) get the best results from your printer with the most efficient use of your system resources.