Interpolating in Photoshop or Genuine Fractals?

Discussion in 'Digital Darkroom' started by jukka|1, Aug 31, 2006.

  1. Hello.
    I have 6 megapixel camera. I want to interpolate to 13*19 size.
    What is best way to interpolate?
    In photoshop:
    Bicubic, Bicubic sharper or Bicubic smoother?
    Or interpolate in Genuine Fractals?
    Has anyone compared?
    After sharpening has been done, is there any difference?

    Sincerely, Jukka
  2. Bicubic sharper.
  3. Bicubic Smoother should be used for interpolating up, Bicubic Sharper for interpolating down.
    Genuine Fractals does a reasonable job, but these are ready and very easy to use, and hard to get wrong if you get the correct one!
    Some people say you should only interpolate up by 10% at a time. I think that was before the CS / CS2 versions as these seem to be ok to do in one go.
    Best thing to do is to try them out and work out yourself what to do.

  4. In Photoshop it costs nothing but a few minutes to test this stuff yourself. So why ask? Also, Photoshop Help tells you the differences between the Bicubic's, as do many a fine book.

    I would suppose GF might be something you'd want to use if you were pushing towards prints much larger than 13x19 inches. A 6MP camera, provides good technique and lens and all that will produce a stunning Super-B sized print.
  5. From PS HELP:
    For Interpolation, choose one of the following options:
    ... Bicubic A slower but more precise method based on an examination of the values of surrounding pixels. Using more complex calculations, Bicubic produces smoother tonal gradations than Nearest Neighbor or Bilinear.
    Bicubic Smoother A good method for enlarging images based on Bicubic interpolation but designed to produce smoother results.
    Bicubic Sharper A good method for reducing the size of an image based on Bicubic interpolation with enhanced sharpening. This method maintains the detail in a resampled image. If Bicubic Sharper oversharpens some areas of an image, try using Bicubic.
    If your 6MP camera is just a point & shoot then all bets are off as its sensor is to tiny and too noisy and lens not sharp to enlarge acceptably as per request.
  6. Jukka, use the smoother, some folks say to do it in steps of 10% I just go to 20x30 inches and get posters that my cusomters go nuts over using my 6mp D70s and my tiny 4mp D2h. While they aren't musuem quality and many of the experts here will pick them apart if you got a sharp image shot at a fast enough shutter speed or on a tripod you will get a sharp enlargement. If it's a little blurry at 4x6 it will be really blury when enlarged. That said try one.
  7. Hi Jukka,

    A while back, I compared various Photoshop methods with Genuine Fractals, and came to the conclusion that there is no fixed answer! Different methods seened to produce results that I preferred from different starting images.

    In one image, Genuine Fractals might do a better job of controlling artifacts in areas of constant tone, but would generate more artifacts along contrasty edges. But the reverse would be the case for another image.

    That's why (for special images) I compare enlargements from several techniques...and choose the one that I prefer.


  8. I'm really curious why you need to interpolate a 6MP image to print 13x19". I do it all the time uninterpolated, print with an Epson 2200 and get excellent results. Interpolation doesn't make a visual difference at this print size.
  9. I have printed 24x36 from my 10D(6MP). I can see no differance between Geniune Fractals and photo in the final image. But GF takes about 4 minutes to complete and PS CS2 takes about 45 seconds.

    If you are going to double the size of the image you want to use Bicubic Sharper, I know everyone says that Smoother is what you want, but for larger images Sharper does a better job. Adobe says to use smoother but Vincent Versaci came up with the Bicubic Shaprer method. Both him and Scott Kelby recommend this method, and after making 6 prints this way I do too.
  10. When you print a 6 MP file to 13 x 19" e.g. on Epson printer, the interpolation is done for you by the Epson printer driver, perhaps without you knowing about it. If you watch printing process on the system, you could see that suddenly the print file size grew up few times larger than the original file size. This is your indication of the printer driver action done for you.

    The driver for R2400, R1800 does very good job utilizing the same techniques used by other special programs. Just use the Best print quality setting and forget file upsizing on your own, unless you are a veteran expert in programs like Spline, etc.
  11. > Has anyone compared?

    See Ron Bigelow's articles on interpolation (an many other subjects):
  12. x


    Are you interpolating in order to make a big print yourself ? If yes, I'd recommend you check out Qimage which will interpolate, sharpen and print in one go. In my experience making A4 prints on an Epson R800 the print driver does not do a great job of interpolation/resizing and Qimage is noticeably better with fine detail. I'd expect the differences to be even more visible on an A3 or larger print.
  13. Although the R800 uses the same ink set as R1800, the 2 printers have different printer drivers, even though graphical interface is similar.

Share This Page