Correct sizing of a picture for printing

Question

Good day all;
I am a wee bit new at all of this so this question may sound a bit simple.
Is there a correct way to size pictures for printing. This is what I have done.
My camera is set of 6 meg’s which gives me a huge original. I want to take this and print on a 4x6.
I bring up the picture, select print > click on “scale to fit media. This gives me the size of
5.333 X 4.
I go back to the picture select: Image>Image Size. Under Document size I enter 5.333 in the Width. The height changes to 4
Question, am I doing this correctly
Thanks All
Chomp

Answer 1

I looked up the resolutions for the Lumix Dmc-F27. Full resolution is 2816 * 2122 pixels, giving an aspect ratio of 1:1.327. If you want 4 by 6 inch prints (aspect ratio 1:1.5), you should crop so that the long axis is 6 inches. The short axis would then be 4.5241 inches and the resolution would be 469 pixels/inch. If you are sending the image to an injet printer, you would want to crop the short axis to 4 inches. In his Image Sharpening with Adobe PSCS2, Bruce Fraser states that the "native resolution" of HP inkjets is 300 ppi and that of Epsons is 360 ppi. He further states that Epsons can benefit from up to a resolution of 480 ppi and that sending more than 720 ppi to the printer can actually degrade image quality. With your camera, I see no good reason to use less than the native printer resolution unless file size is a concern.
In your situation, it would make sense to crop without resamplilng and send the image to the printer at 469 pixels per inch (assuming that you are using an Epson printer). If you don't mind arbitrary cropping, you could create a Photoshop action to automate the process and you could add suitable sharpening in the process. To simplify things, I would recommend turning off sharpening in the camera.
If you know that you will not need more than 4 by 6 inch prints, I see that the camera has a 1600 x 1200 pixel mode, which would give a 300 ppi 4 x 6 inch print.
If you are having the prints done at Walgreen's or Walmart and do not mind aribitrary cropping, you could likely send the native images to the printer and let the printer handle resampling and cropping. These machines usually print at 300 pixels/inch.