How large can I extrapolate an image

Discussion in 'Digital Darkroom' started by edward_carreon|2, May 19, 2019.

  1. Hi folks,

    First time posting here.

    I have some landscape images that I shot at ISO 64. File size is about 8200 pixels wide on a Nikon 850 or about 27.5 inches wide.

    Would anyone have experience increasing the size of image files for fine art printing (for sale), and if so, how far can I increase the file size before I see degradation? Can I increase the size to 40 inches wide from the native 27 inches wide?

    This is a link to some of the images I would like to extrapolate to large file sizes. Landscapes by Ed Carreon

    Thank you for your time and attention.
  2. digitaldog

    digitaldog Andrew Rodney

    For a modern inkjet output from say an Epson, you can get away with 180-200 pixels per inch without interpolation easily especially if (and this makes a big difference) you've used good capture and output sharpening for that media.
    If you have to interpolate, Photoshop and a bit better, Lightroom can do the job quite well, again with good sharpening. Specialized interpolation software like that from say Topaz is really more useful taking very low resolution images for larger output than you have at hand, KISS. ;)
  3. Forget "native" size. Pixels are pixels and inches are inches. 8200/40 is 205 ppi. That should give a decent print, especially if viewed from any sensible distance. It has a bit of a learning curve, but Qimage is extremely good when you need to interpolate, or when you don't, and doesn't cost too much.
  4. By rule of thumb, you can double the size of a good image by resampling. It depends on the subject, method of display and personal taste. You can enlarge about any digital image to billboard size (50'). The pixels can be the size of oranges and still look continuous from street level.
  5. For large prints, anything in the 180ppi range will look very good.
    digitaldog likes this.
  6. 8200 pixel width / printer resolution per inch = max width
    8200 / 300dpi = 27.3 inches
    8200 / 200dpi = 41 inches.
    8200 / 150dpi = 54.7 inches
    So check if you can adjust the printer resolution.
    If you are printing that big, you likely do not need a high printing resolution, because you are viewing from a farther distance.

    Critical question, what is the viewing distance?
    I recall that a 2x3 foot print out of a 6MP camera looked pretty darn good, from across the room.
  7. digitaldog

    digitaldog Andrew Rodney

    As the late, great Bruce Fraser used to say: "The distance a photographer views a print is based on the length of his nose" :)
    Yeah, for others, the viewing distance makes a huge difference.
    Dave Luttmann and Ed_Ingold like this.
  8. Any photo not behind a barricade will be examined at pixel level, paintings for brush marks.
  9. I recently did a shot for a trade show booth. The printer required 100 ppi for images 8' tall. Seemed excessive, but they looked good in the end.
  10. I just want to re-emphasize that you cannot ignore the variable of how close you are to the final image..

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