Tips For Better Printed Output With Photoshop
by Steve Maller
© 2000 All Rights Reserved

Some of my friends have asked me how I manage to get attractive photographs from my Epson Photo 1200 inkjet printer. After telling the story to several of them, I decided once and for all to write a few notes down.

I take a lot of digital photographs with my Nikon Coolpix 950, and I scan the best of my 35mm photographs with my Polaroid SprintScan 4000 scanner. I play around with the images in Adobe Photoshop 5.0 on my Power Macintosh G3. A year or so ago, I picked the Epson Photo 1200 as the best reasonably-priced photo-quality inkjet printer for my home digital darkroom. The published resolution for this printer is 1440*720 dpi, so I use that as a reference for this document. Any other resolution can be substituted, as well as any other imaging software. And although all of these notes apply to my Macintosh, they should be applicable to other systems, too.

The number of pixels displayed per unit of printed length in an image, usually measured in pixels per inch (ppi). An image with a high resolution contains more, and therefore smaller, pixels than an image of the same printed dimensions with a low resolution. For example, a 1-inch-by-1-inch image with a resolution of 72 ppi contains a total of 5184 pixels (72 pixels wide x 72 pixels high = 5184). The same 1-inch-by-1-inch image with a resolution of 300 ppi would contain a total of 90,000 pixels.
The key to this exercise is understanding a few basic principles of imaging. To quote Adobe from the Photoshop 5.0 help file:

figure 1
Figure 1: Image Size dialog box
Screen resolution
How does this translate into practical terms? Let's consider for this example an image from my digital camera. Images at the Nikon's highest resolution are 1,600 pixels by 1,200 pixels in size. If viewed on a screen at typical Macintosh screen resolution of 72 pixels per inch, these images would be about 22 inches by 16 2/3 inches.

Printer resolution
An image of the size above wouldn't look very nice printed out because the individual pixels would be clearly visible, resulting in a very "bumpy" image. The goal of this exercise is to figure out how to print images that do look nice printed out.

Figure 1. to the right shows the dialog box that you get when you pull down the Image menu and choose Image Size.... As you can see, the Print Size listed in the dialog box corresponds to the numbers described above in the Screen Resolution section. Now we'll adjust the numbers in this dialog box to optimize our output.


figure 2
Figure 2: A reasonable resolution value
The Answer
Rather than going into exhaustive detail on the mechanics of how printers think, I decided to just give you the answer. (If you really want to know more about how this all works, I encourage you to dig around a little on the Internet!)

As you might guess from what you've read so far, we'll need to twiddle with the numbers in the window above to get good printed output. The magic formula depends on following two simple instructions.

Once this process is complete, you will probably say something to the effect of "Gee whiz, Steve, I just spent $1,000 on a whizzy new digital camera and you're telling me I can't get anything more than 3 by 4 inch prints?" That's not really true. I encourage you to try other values in the Resolution field. For example, you can use 180 instead, with will end up filling more of an 8.5x11 page.

figure 3
Figure 3: Using Size instead of Resolution
I should also say that many printer drivers (such as the Epson) do a pretty reasonable job of stretching and smushing pixels, so you can instead enter values in the Width and Height fields, and let the Resolution value calculate itself. It probably won't be an even multiple of the maximum resolution of your printer, but you should judge the results for yourself.

In Figure 3, I've entered the traditional 8x10 inch values, and Photoshop has changed the Resolution to 160. In my opinion, this is typically too big for photographs from my Nikon, but again, it's your ink, your paper and your photograph.

Important reminder: Make certain you go into the Page Setup... dialog box and set the orientation of the document to either Portrait or Landscape to match your photograph.

If you have access to higher-resolution photographs, such as the ones that I get from my Polaroid transparency scanner or the images that you get from a PhotoCD, you can have a lot more fun, and of course you'll end up with more data to print. In these cases, you're often able to size photographs up to 8x10 and higher, even at pleasant resolutions such as 360 dpi.

The Last Word
I dearly appreciate the extraordinary effort that has gone into this field, and I salute the brilliant engineers and visionary product people who have designed and brought to market products like the Nikon digital cameras, the Epson photo printers, and Adobe Photoshop. I feel as though, for the first time in my life, I can do something that I can confidently call "art". It's a feeling that I hope many of you are able to feel, too.

Thanks for stopping by.

June 1, 2000

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