image up-sizing

[wmchauncey]

I've got numerous 22 MP (12.5 x 18.75) images that are stellar @ 200% magnification...I am also anal retentive about having prints capable of nose-length viewing distance.
What is the best way to up-size that 22 MP image to something in the area of 24 x 36" and maintain that same print viewing distance?

[Bart_van_der_Wolf]

I've got numerous 22 MP (12.5 x 18.75) images that are stellar @ 200% magnification...I am also anal retentive about having prints capable of nose-length viewing distance.
What is the best way to up-size that 22 MP image to something in the area of 24 x 36" and maintain that same print viewing distance?

Hi,

Usually, upsampling will get you no benefits for resolution, but only for upsampling quality. Most upsampling algorithms do better than the printer driver. However, the better upsampling programs/algorithms do add some resolution by creating a better definition of sharp edges and tiny detail.

"PhotoZoom Pro", and "Perfect Resize" allow to increase resolution that way, and are the best choices if you want to upsample and gain quality. Other solutions will, at best, not lose to much quality.

As  a generally good upsampler for print, with excellent halo free output sharpening capabilities, Qimage Ultimate must be mentioned. While it's a Windows application, it is also used by MacOS users while running under e.g. "Parallels". It may well produce upsampling quality that is hard to distinguish from the 2 more dedicated applications mentioned earlier.

Cheers,
Bart

[rdonson]

It your 22 MP images are as stellar as you say then they should easily produce 24 x 36 prints.  Are you printing them yourself?  If so, which printer, paper and software are you printing with? 

[Bart_van_der_Wolf]

It your 22 MP images are as stellar as you say then they should easily produce 24 x 36 prints.

Correct, but there is a difference between good and best.

24'' x 36'' is 14000 x 21600 pixels on a 600 PPI printer, or 17280 x 25920 pixels on a 720 PPI printer. That requires an approx. 400% upsampling of the starting resolution. Adding output sharpening at that final resolution, will allow to sharpen after all resampling is done, and PhotoZoom Pro or Perfect Resize will add resolution to reach the upsampled size.

Cheers,
Bart

[digitaldog]

It your 22 MP images are as stellar as you say then they should easily produce 24 x 36 prints.  Are you printing them yourself?  If so, which printer, paper and software are you printing with?

I'm with you. I've done lots of tests with various products out to print. 200% isn't a large enlargement with a clean capture and doesn't require any special software. Use Photoshop or give the print driver a try doing so. Good capture and output sharpening plays a far larger role in the quality than software to upsize this small amount.

[wmchauncey]

FWIW, I don't have a printer and will be farming them out...metal prints only.

[rdonson]

FWIW, I don't have a printer and will be farming them out...metal prints only.

Depending on who you farm out the printing to they're likely to have a very good RIP for uprezzing your image.  Check their website to see what their image size requirements would be for a 24x36.

[BobShaw]

It your 22 MP images are as stellar as you say then they should easily produce 24 x 36 prints.  Are you printing them yourself?  If so, which printer, paper and software are you printing with?

+1
I have printed many prints that size from a 5DMk2 at 21MP. Not as good as medium format but certainly saleable.
I was just editing and printing an image for an exhibition and exported two files as I always do. A full size 6169 x 3083 pixel 114.1MB 16 bit ProPhoto TIFF for printing and a 1024 x 512 pixels 316KB  sRGB jpg for the web. Guess which one I then dragged onto Mirage Print to make the 800 x 400 mm print? I could tell there was something wrong when it started to come out but by the time I put my glasses on and was convinced to trash it there was 250mm out. I was actually surprised that it was even half reasonable. Matte paper probably helped.

[earlybird]

What do the specialty programs do that you can not do with a two step bicubic resize and output sharpen?

Thank you.

[Bart_van_der_Wolf]

What do the specialty programs do that you can not do with a two step bicubic resize and output sharpen?

Hi,

The specialty programs use dedicated up- or down-sampling algorithms that produce fewer artifacts (like jagged edges, or aliasing/ringing/halo), and yet are better at retaining original sharpness, and in certain situations produce higher resolution than the original image had (e.g. powerlines, or tree branches, or building/window edges don't simply get 4x as wide and blurry when resampling to 400%). The details either stay narrower or just stay as sharp as they were at 25% of the output size, and smooth gradients stay smooth, not posterized.

If the resizing was technically done well (e.g. without introducing halos), then the new image at final output size (which prevents low quality resizing by the printer driver) will also survive more output sharpening, without creating or showing artifacts. The applications also allow to add noise to reduce the plastic look of very large magnifications, and thus also reduces the posterization of smooth gradients.

Cheers,
Bart

[earlybird]

Hi Bart,
 Thank you for explaining.

 

[Bart_van_der_Wolf]

The specialty programs use dedicated up- or down-sampling algorithms that produce fewer artifacts (like jagged edges, or aliasing/ringing/halo), and yet are better at retaining original sharpness, and in certain situations produce higher resolution than the original image had (e.g. powerlines, or tree branches, or building/window edges don't simply get 4x as wide and blurry when resampling to 400%). The details either stay narrower or just stay as sharp as they were at 25% of the output size, and smooth gradients stay smooth, not posterized.

I've attached an example. The original (shot with an EF 70-200mm f/4 L @ 200mm , f/4.5 , 1/800 sec.) was a crop of 800x800 pixels. The two resampled versions (link) are from PhotoZoom Pro 6 and from Perfect Resize 8, and have been upsampled to 450% (like a 22MP sensor image to 24 x 36 inch @ 720 PPI). The print size of the magnified crop at 720 PPI is 5 x 5 inch. Had the output medium been known, one might have have additionally compensated for output medium losses, like e.g. ink diffusion.

Also, a reminder, it's not how the output files look zoomed in to 100% or more, but how they print. So the somewhat vectorized close-up look, will look normal yet crisp in actual print, without jaggies and blurred edges. To get a print preview impression on display, one should zoom out to a zoom percentage of display_PPI / 720 PPI, with a good resampling method (not a simple zoom, but with a real resampling).

The Perfect Resize version lost a bit of D-min during the conversion (maybe a bit too much noise was added), so will print with lighter shadows.

Cheers,
Bart

P.S. I've also attached a Lightroom (5.7.1) upsampled to 450%, and output sharpened (Glossy Standard), version of the crop.

[AFairley]

I'm with you. I've done lots of tests with various products out to print. 200% isn't a large enlargement with a clean capture and doesn't require any special software. Use Photoshop or give the print driver a try doing so. Good capture and output sharpening plays a far larger role in the quality than software to upsize this small amount.

Photozoom will give visibly better results than straight out of Lightroom on a 24x36" print where the uprez from the original file comes to around 200%.  I have actually printed the comparison.  The difference is most apparent on diagonals.

[BobShaw]

What do the specialty programs do that you can not do with a two step bicubic resize and output sharpen?

Others will give a more tech answer, but from my experience and perspective ...
1. You don't have to know anything about either of those or do them.
2. You don't have to have a preset for every size of print, every size of paper and every type of paper on every programme that you print from.
3. You don't have to redo all of those presets every time you update a programme or a driver or add a printer.
4. WYSIWYG. No wrong way wrong size prints.
5. You save a lot of ink and paper.

[samueljohnchia]

I've attached an example.

Thanks Bart. Could you say if Perfect Resize or Photozoom Pro is better at upsampling? In a previous example (I think it was a sailing ship) you posted, the Perfect Resize attempt was clearly worse than PZP, but here I am not so sure. The huge amount of color noise is not helping, neither is the luminance noise. Noise aside, the Perfect Resize rendering seems to be more organic, with less smudging, like on the branches. PZP tends to result in not halos, but more like ghosts on some of the edges.

[langier]

I've printed a several hotels full of 20x30 to 30x40 prints...all from 10-12mp captures, even a few 4-6mp captures, all without special resizing software, stair-step up-rezzing, pricing files with the same dpi as the printer. And being anal-retentive about looking at images from 12-24 inches away to judge print quality, they look great.

The key is good craft in capture and processing, good editing choosing great images and then printing away.

Some images just won't work large but that's where good editing comes in. Some require a bit more final sharpening than others.

On my studio wall I have a 30x40 image printed from a 16mp m43 capture and from 2 feet away, the other side of my counter, it looks very nice, including the sharpness and detail.

Many of today's printers do quite well on images with lower resolution than usually required by our normal rule-of-thumb for good output. Even 100 ppi input for some images will work, especially on canvas textured paper. For many of these jobs, I didn't have time for fancy up-rezzing programs or strait-step interpolations in the production.

I remember that probably 10-15 years ago. David Pogue took a bunch of prints to the New York Public Library and asked 100 people what they thought of a set of 11x14 prints, shot with cameras from 1.5mp to probably 16-20mp. Only one person could see any difference out of the group and he was trained in real-life.

If you are farming this out, why not send one of your images out and have a sample print created to see what you think?

One thing that helps is to back off from your prints a little to more proper viewing distances or get older with fuzzier vision :-)

[Bart_van_der_Wolf]

One more example (link). Attached crop is 800 x 800 pixels, resampled to 450% (3600 x 3600px) with Perfect Resize 8 and PhotoZoom Pro 6.  Printed at 720 PPI (with 'Finest Detail') it would produce a 5 x 5 inch output size. Output sharpening could be optimized for a specific medium.

To get a print preview impression on display, one should zoom out to a zoom percentage of display_PPI / 720 PPI, with a good resampling method (not a simple zoom, but with a real resampling).

Also attached a Lightroom 5.7.1 upsampled export, with output sharpening (Glossy Standard).

Cheers,
Bart

[Bart_van_der_Wolf]

Thanks Bart. Could you say if Perfect Resize or Photozoom Pro is better at upsampling?

Hi Samuel,

I think it depends on the image content. Perfect Resize uses a 'fractal' approach, whereas PhotoZoom Pro (S-Spline Max method) uses a more 'adaptive Vector' approach. So PR could look more natural, while PZP could/does look more smooth (and also with sharper looking results) in high contrast edges. However, at actual print size the differences will be small, with maybe a tiny edge (pun intended) to PhotoZoom Pro.

In a previous example (I think it was a sailing ship) you posted, the Perfect Resize attempt was clearly worse than PZP, but here I am not so sure. The huge amount of color noise is not helping, neither is the luminance noise.

In the printed output, the noise would be hard to detect, but one can add to taste or leave it switched off. Especially very large magnifications can start looking too sharp on edges in relation to missing surface structure. Noise will fool the Human Visual System (HVS, which is partly eyes and a lot of brain work) in seeing detail where there is none (just like we want to see non-existing shapes in clouds). The HVS is good at pattern recognition (even if imaginary), because that protects against input overflow. Reducing the input stream to more simple shapes and edges (also helped by the HVS's Contrast Detection sensitivity which favors somewhat lower spatial frequency contrast as a surrogate for sharpness) is helpful to detect dangerous situations and react to them in time.

Noise aside, the Perfect Resize rendering seems to be more organic, with less smudging, like on the branches. PZP tends to result in not halos, but more like ghosts on some of the edges.

The fractal approach does indeed try to create organic looking surface structure, the vector approach preserves edge detail better (especially useful for architecture and some sorts of product photography). Perfect Resize has more controls, which the perfectionist in me likes, but it also makes it a bit harder/slower to settle on 'optimal' settings, where PhotoZoom Pro is faster to reach an 'optimum'. But both have settings that can produce similar looking output, so I used different settings to demonstrate the specific strengths rather than matching results.

Both will generally create sharper looking output than other applications (maybe PhotoZoom Pro slightly sharper due to flawless edges, which is what the Human Visual System likes), more so at larger magnifications.

Probably the many point is that, these applications consistently produce (equal looking or) higher resolution upsampled output than the alternatives (depending a bit for it being visible on the upsampled amount of the output), although it adds another step to the workflow.

With Photoshop one can of course layer the result of upsamples with different settings, and mask in/out certain areas. Perfect Resize tends to introduce a small pixel offset, whereas PhotoZoom Pro corresponds with e.g. Lightroom, so layering should be done with a bit of care if Perfect Resize is used.

Cheers,
Bart

[wmchauncey]

One thing that helps is to back off from your prints a little to more proper viewing distances

Back off how far?  IMHO, if ya gotta back-off it would indicate an inadequate print.

[samueljohnchia]

I think it depends on the image content. Perfect Resize uses a 'fractal' approach, whereas PhotoZoom Pro (S-Spline Max method) uses a more 'adaptive Vector' approach. So PR could look more natural, while PZP could/does look more smooth (and also with sharper looking results) in high contrast edges. However, at actual print size the differences will be small, with maybe a tiny edge (pun intended) to PhotoZoom Pro.

The fractal approach does indeed try to create organic looking surface structure, the vector approach preserves edge detail better (especially useful for architecture and some sorts of product photography). Perfect Resize has more controls, which the perfectionist in me likes, but it also makes it a bit harder/slower to settle on 'optimal' settings, where PhotoZoom Pro is faster to reach an 'optimum'. But both have settings that can produce similar looking output, so I used different settings to demonstrate the specific strengths rather than matching results.

Both will generally create sharper looking output than other applications (maybe PhotoZoom Pro slightly sharper due to flawless edges, which is what the Human Visual System likes), more so at larger magnifications.

Cheers,
Bart

That's very insightful Bart, thanks very much.

When enlarging grainy images, I see that Perfect Resize does a much much better job than Photozoom Pro, which tends to generate weird artifacts in the upsampled grain structure.

I'm seeing that Photozoom Pro's "perfect edges" are not as perfect as I used to think they were. I've attached a magnified portion of your first example, and the blue arrows point to some of the offending regions where Photozoom Pro doesn't seem to do as well. 6-7 pixel halo/ghosting, blurry edges which transition to almost too sharp edges, very strange looking. In a test image of mine, I found that PZP tends to emphasize any zipper artifacts from demosaicing which Perfect Resize avoids. I agree that when the edge is rendered sharply, PZP is sharper. That is quite clear in the new owl eye crop. It's interesting to study where one does better than the other. Indeed, a lot can be invisible at print sizes.

I see that Perfect Resize generates some weird color fringing artifacts on the high contrast edges. What's up with that?