Preparing Images for Printing

EysterKathy_23Once you’ve decided to print your image using either a photo inkjet printer or a printing service, you still have to prepare the file correctly to ensure you get quality results. This involves three steps:

  1. Set the resolution.
  2. Size the picture.
  3. Sharpen the image.

If you are sending the picture out to a photo lab for reproduction, you need to take two additional steps:

  1. Convert to the appropriate color space.
  2. Save the photo in the appropriate file format.

 

1. Set the Printing Resolution

First, you need to ensure that you have enough pixels for the size you intend to print the photo. This is called resolution and technically is described as “pixels per inch” or ppi. Specifying the appropriate resolution is a quality setting for your print. High resolution ensures that fine details are reproduced crisp and clear. Too low a resolution softens edges and blurs fine detail, making your print look slightly out of focus.

What resolution setting do you need? As a general guideline, 300 ppi works well for small to medium prints (4×6 inches up to 16×20 inches). I recommend having at least 200 ppi for quality prints. More than 400 ppi makes your file size larger without necessarily producing a noticeable improvement in sharpness.

Resolution is closely tied to print size. If you don’t have enough pixels available for the size you want to print, you may not be happy with the results. So the question always is “How big can I print?” (Almost no one ever asks “How small can I print?” That answer is “as small as you want!”) Here’s how to figure it out.

Start with the total number of pixels you have in your image. Let’s say your original camera image is 2912 pixels tall by 4368 pixels wide. (You can view the pixel dimensions of your photo in your editing software.) If you use the recommended resolution of 300 ppi, you need to know how far the available pixels will spread out in your print. So divide each dimension (width & height) by this resolution setting:

Original photo dimensions 2912 pixels x 4368 pixels  •  Resolution 300 ppi

2912 pixels ÷ 300 ppi = 9.7 inches

4368 pixels ÷ 300 ppi = 14.5 inches

In this case, you can print the picture 9.7 inches by 14.5 inches, enough for an 8×12 print or smaller.

If you want a larger print, try using a lower resolution setting, such as 200 ppi. Use the same formula to calculate how large you can print the image at this resolution.

Original photo dimensions 2912 pixels x 4368 pixels  •  Resolution 200 ppi

2912 pixels ÷ 200 ppi = 14.5 inches

4368 pixels ÷ 200 ppi = 21.8 inches

By lowering the resolution to 200 ppi, you can print the same image up to 14.5 inches by 21.8 inches, sufficient for a 12×18 print or smaller.

Cropping reduces the number of pixels available for printing, so always try to get as close to your final composition in camera as possible.
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2.  Size the Picture

Here is a fundamental issue: Camera image proportions are different from traditional paper proportions. The proportions of our photo (the relationship of the width to the height) as it comes from the camera do not match most of the standard paper or frame sizes.

A photo from a digital SLR camera, without any cropping, has a proportion of 2×3. Only 4×6 and 8×12 paper sizes match this exactly. Other traditional print and frame sizes, such as 5×7 or 8×10, do not match. This means that some of your image needs to be cropped so it fits these different proportions. You will be happiest if you decide which parts of your image you can afford to crop rather than leaving the decision to the lab.

If you have decided on a creative crop, such as turning your original photo into a square or panorama, or if you just adjusted each side “free-hand” to give your picture the best composition, your image won’t match traditional paper sizes either.

So save a copy of your original image and include the final size in the new name. Then use your photo editing software to crop your image to fit the proportions of the paper you intend to print it on.

If you are going to print the picture on your own photo inkjet printer, your only concern with size is that the longest edge of the photo fits on the longest side of the paper you are printing on. This means you have more freedom to use different image proportions than when you order from a printing service. But keep in mind that using non-standard proportions for your photo means you will need a custom mat and/or frame to finish the piece.


3. Sharpen the Print

After you have set the resolution for a quality print and sized the picture, you need to apply some sharpening. This is not the same sharpening you apply when editing your photo. This step compensates for what happens when pixels are converted to drops of ink from your home printer or grains of silver from a photo lab print. In either case, this “translation” from one medium to another can cause important edges in the image to become soft instead of staying crisp.

How much you sharpen the image you are going to print depends on the resolution and size of the print you are making as well as the paper surface. Therefore, sharpening is always the last step, after resolution and sizing. Note that this is NOT a correction for blurry or out of focus pictures.

Because every print is potentially a different size and resolution, and because there are a variety of methods and tools to apply sharpening for your print, I can’t give you any specific guidelines.

At this point, if you are using your own photo inkjet printer, you are ready to load a piece of photo paper and send the file to the printer. However, if you are going to have a printing service reproduce your image, you have two additional steps to follow.

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4. Convert to the Correct Color Space

A color space is a set of colors used to reproduce and display the hues in your image. Think of a color space as a box of crayons. Different types of photo printing equipment use different color spaces (boxes of crayons). Your picture file needs to be saved in the correct color space to ensure the lab can recreate the colors you captured.

There are two color spaces commonly used for printing, sRGB and Adobe RGB. The most commonly used color space is sRGB (“standard” RGB). If you have any doubts about which color space the photo lab needs, use sRGB. It’s the safest color space since all digital cameras can record pictures using this color space and all printing processes recognize it.

Some professional print labs are able to use the larger Adobe RGB color space. A few digital cameras can record colors using this space and a few photo editing applications can also work on pictures in this space. Only use Adobe RGB if you are certain the photo lab knows how to interpret those colors.


5. Save in the Required File Format

Photo labs can print pictures that are saved in either JPEG or TIFF file format.

JPEG is the most commonly used file type; it’s the format your digital camera uses to save your pictures. JPEG is a “lossy” format. This means that some information is discarded when your picture is saved in order to create a smaller file that takes less time to upload. Since you want the best quality file for your print, be sure to choose the highest quality setting (12 or 100%). Also, save using the “Baseline (Standard)” option, if you are given a choice in your photo editing software.

TIFF is another common file type used for printing pictures at professional labs. It does not discard any information when saving your picture, so it produces a much larger file that takes longer to upload. Be sure to flatten any layers and change the image to 8 bits/channel when saving your photo as a TIFF file. Also confirm that the lab can print from a TIFF file before sending your picture.

Summary

So remember to follow these steps when preparing your pictures for printing:

  1. Set the resolution.
  2. Size the picture.
  3. Sharpen the image.

For photo lab printing:

  1. Convert to the appropriate color space.
  2. Save the photo in the appropriate file format.

Taking these steps will help ensure you create a great print of your favorite photo that you’ll be proud to display.

8 thoughts on “Preparing Images for Printing

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Barry Grivett

Kathy,
Obviously, you take our language seriously: a beautifully written article with nary an unneeded word.

And, your article should prove useful to new printers. I wish you would step into the subject sidestepped in “3. Sharpen the image.”, paragraph 3.

Thank you for your contribution.

Kathy Eyster

Thanks for your compliments on my writing, Barry! Decades as an English major contributed! :-)

Dealing with #3, paragraph 3, on sharpening is complicated by the variety of photo editing software available as well as the myriad tools within those programs to apply sharpening. So getting more specific in a useful way for a blog post is difficult!

I can offer these suggestions:

* Higher resolution images can tolerate stronger sharpening compared to lower resolution images before displaying unwanted “side effects” (artifacts).
* Smaller prints (4×6 inches) may need more sharpening than much bigger prints (16×20 inches plus) due to the effect of viewing distance. You must hold a smaller print closer to see it and stand back from a larger print to take in the whole image. Therefore, effective sharpening can be more important at smaller, hand-held sizes than larger, wall display sizes.

All this contributes to the idea that sharpening is both a science and an art!

Kathy

Ursula Carpenter

Thank you for this article, Kathy!

Do you have any advice for printing on different surfaces? What should I consider when printing on metal(tin) plates?

Thank you.

Kathy Eyster

You’re welcome, Ursula.

Regarding printing on different surfaces, the process is really the same. The only place you might make slight adjustments would be due to the glossy or textured surface of the medium. Prints on metal (usually aluminum) tend to be highly glossy. So they need good sharpness but not over the top. On the other hand, printing on a very textured watercolor type paper might require more sharpening than glossy to help preserve crisp edges on the rougher surface.

The best advice is to test sharpened and less sharpened images on the same surface and see what you think!

When in doubt, it is preferable to UNDER sharpen than over sharpen an image.

Kathy

Profile photo of Barry

Barry Grivett

All interesting; likely, there are books & tutorials on this subject.

Still, I appreciate your advice.

Thanks again.

Kathy Eyster

You’re welcome, Barry! Yes there are books & tutorials on the subject, but frequently they focus more on the software how-to and overlook the “big picture” which is what I wanted to do in my post.
Kathy

Tricia

Thanks for the article Kathy! Great review and it was perfect timing as I was preparing images for print and getting very confused about the sizing and resolution. You made it much easier to understand.

Kathy Eyster

You’re welcome, Tricia. Glad it was helpful and timely!
Kathy

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