Poster size upsizing

CM
Posted By
Carol_McLinko
Feb 5, 2007
Views
309
Replies
5
Status
Closed
Hi,
I’m using Photoshop CS on Windows with a Sceptre monitor and have just upsized a 4’x6′ digital photo to 16"x20". Then I realized I first wanted to do a print at 4"x6" to test the colors at a local online print store. Is it ok to trash each 10% increment upsizing until I return to the original size or is it best, for resolution sake, to use an unaltered upsized photo? After I see the printed version for colors, then I can upsize to my desired end result of 16"x20". My main concern is for the resolution of my final 16"x20" print. So my question is, can you upsize a photo, return to the original size and later upsize again without losing any resolution?

Thanks,
Carol
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B
Bernie
Feb 5, 2007
You do realize upsampling will not add detail to you image right?

so my question is, can you upsize a photo, return to the original size and later upsize again without losing any resolution?

How about taking the hires, downsampling it and saving a copy?
C
chrisjbirchall
Feb 5, 2007
Every time you resize an image you lose quality – regardless of whether you upsize or downsize. As Cyb has so rightly pointed out, you cannot insert detail which was not there in the first place, so upsizing results in "invented" pixels based upon their neighbours. Downsizing also results in "invented" pixels when (for instance three pixels are replaced by two).

Your mention of the 10% increments leads me to guess you are using the "step" method of upsizing. Photoshop engineer Chris Cox has stated categorically that since the advent of "Bicubic Smoother" (upsizing) and "Bicubic Sharper" (downsizing) there is no advantage in the Step or Stair method.

As for reducing your 20×16 back down to 4×6". Why would you want to do this. All you need is to open the original 4×6" and print that one instead. You did work on a copy of the original didn’t you?!

Hope this has provided some further insight.

Chris.
AC
Art Campbell
Feb 5, 2007
Carol,

Nothing to add to Chris’ and Cy’s posts on the mechanical side of things, except to point out that "testing the colors" is really only valid if it’s the same machine (or type of machine) that is going to print the final print.

If the local online shop uses a different type of machine than the one that will produce the final output, the color of the final is very likely to be different than the test print’s.

Art
CM
Carol_McLinko
Feb 5, 2007
Hi,

Cybernetic, I realize any change results in "invented" pixels and know it won’t add detail, but I needed a larger photo of my original. From what I’ve read, using bicubic smoother on 10% increments, gets you there gradually, therefore better than taking a quantum leap in size. Are there any other preferred ways to result in a larger pic for framing purposes? Also, what does "taking the hires" mean?

Chris, I’m not familiar with the step or stair method, as I do use the bicubic smoother. Thanks for pointing out that bicubic sharper is for downsizing. What actually happens in bicubic sharper? Yes, I do have a preserved original and appreciate the detail in your explanation.

Art,I am aware of different printer outcomes and do appreciate you highlighting it. I am having a small copy tested at a local shop, to be sure I will be pleased with the outcome of a much larger print. That’s why I’m not test printing at home.

What printers do you recommend for home use, as this is, at present, a hobby?

Thanks,
Carol
AC
Art Campbell
Feb 5, 2007
I’ve been happy working through several generations of Epsons. If you’re going to do mostly small prints though, like smaller than 8×10, I’d look at the Kodak dye-subs.

Art

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