How large can you upsize/interpolate an image before getting pixelized (can be noticed if viewed up close)?

How can you determine if you image is good enough for certain size? View it at 100% in PS or view it in Print Size in PS (approx 24% @ 300dpi)?

Are there better interpolation method(s) than PS Bicubic?

you can use genuine fractals

or you can upsize interpolate via 5% until you reach desired size

For print purposes, I think you can double the size of your image without interpolation if your original capture and resolution are good. A file at 300 ppi can double just by reducing the pixels down to 150ppi. I've printed at 150 before and have not noticed a deterioration in print quality.

If you want to go the interpolation route, going up in size is best to use Bicubic Smoother in Photoshop. Do some minor sharpening after the upsize. Going down in size, preferred is Bicubic Sharper.

For print purposes, I think you can double the size of your image without interpolation if your original capture and resolution are good. A file at 300 ppi can double just by reducing the pixels down to 150ppi. I've printed at 150 before and have not noticed a deterioration in print quality.

If you want to go the interpolation route, going up in size is best to use Bicubic Smoother in Photoshop. Do some minor sharpening after the upsize. Going down in size, preferred is Bicubic Sharper.


Agree with Nick on this.... I regularly print 12x15 bird photos from crops as small as 4 MP (about 150 native ppi). If the capture is pixel-sharp, feather detail is still good when viewed at the eyes' MFD (10").

For old jpeg captures, I convert to 16-bit TIFF before doing any processing then upres to 300 PPI via bicubic smoother (this lessens the formation of haloes). For RAW shots, I upres in ACR during conversion, then just crop to the final size in post process.

Romy

I'll share a workflow here that works quite well. I can't remember where we got it from but here goes:

1) Crop your image as you like but with interpolation turned off. You might get some strange resolution ppi like 312 ppi but leave it.
2) Now in one interpolation move using Bicubic Smoother, take your image to 20% above your final size and at the resolution you want. So if you want a 20x30 print at 360 ppi, interpolate to 24x36 at 360ppi.
3) Sharpen. Use your best judgment here.
4) Then down sample using Bicubic Shaper to your final print size of 20x30 at 360ppi. No need to sharpen the image.

This method is just as good or even better than the stair step interpolation that my colleague Nino Carandang swears by.

I used Lanczos interpolation on this one @ 150dpi for the photos. The lines and text are shapes/paths.

It was relatively quite good for that size of print graphics even up close.

http://static.flickr.com/80/280582497_a9fce467ec_o.jpg

Forgive the use of free stock photos. :S

Only drawback I noticed with lanczos was with interpolating sharp wide curved shapes produced some aliasing like this one:

http://static.flickr.com/83/280589631_799ff104cb_o.jpg


Thanks for the tip Nick! I'll surely use this step with our next project! :)

Randall,

Waht software do you use for the Lanczos interpolation? I've been looking for software(s) that can do different different interpolation methods like Poly3, Spline16, Spline36, Sinc256 etc.

Xnview can do it, and it's free for non-commercial use. :)

It has lanczos, hermite, bell, gaussian, mitchell, hanning, bspline, etc. interpolation methods. :Grin:

With all the stated methods above, is it really possible to create huge prints without seeing any form of pixelation up close?

I have very little experience printing beyond 10"x15" (Frontier) and my one and only huge print is that of my 2 daughters (I wouldn't care enough to notice the pixels). As such, I always think that to expect zero pixelation on a 8-foot high print (like those on store displays) without seeing any pixellation from 6 inches away is impossible?

I see the question "..how big can I print with pixelation.." posted but (IMHO), one should also state the viewing distance in order to get the correct answer.

Or has technology finally caught up and it is possible to make a huge print without pixellation within arms length or less?

Xnview can do it, and it's free for non-commercial use. :)

It has lanczos, hermite, bell, gaussian, mitchell, hanning, bspline, etc. interpolation methods. :Grin:

Thanks Randall!. I think i'll use my first name :)

if you have money to burn you can also try using genuine fractals. :)

if you have money to burn you can also try using genuine fractals. :)


No need JP. Tried XnView Mitchell :) Interpolator. It can interpolate to more than 30,000 pixels which the expensive Genuine Fractals cannot :Grin:

@jerry

In my experience, it depends on how the image will be used and displayed.

For example, this image was interpolated and upclose, it's pixelated and a little muddy. The lines and text are vector, that's why they're sharp:

http://static.flickr.com/106/283517256_13c4cff772_o.jpg

But using it as an interior graphic wall, the pixelation is alot less obvious and is actually not really that noticeable since you need to back-up to view and appreciate a large graphic in confined spaces such as this:

http://static.flickr.com/109/283517254_ed50c834ec_o.jpg

It won't be the same with exhibitions where people will view the image both from a far and near vantage point where pixelation and aliasing are a big no-no.