Tony Northrup - The TRUTH: Hi Megapixels + BIG Prints are a WASTE?

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blue_skies
blue_skies Forum Pro • Posts: 11,849
Re: dpi ~= ppi
1

JimKasson wrote:

  1. blue_skies wrote:

Ceistinne wrote:

blue_skies wrote:

JimH123 wrote:

Tony Northrup just posted a video titled: The TRUTH: High Megapixels + BIG Prints are a WASTE? iPhone vs Sony a7R IV vs Sony a7 III

Interesting comparison. And he did come to the conclusion that to make big prints, that the number of pixels did matter.

I would like to see another twist to this test. And that would be to use a similar panel of judges to look at images the same way, but to add another category. I have been playing around with resizing SW and have compared ON1 Resize, Photoshop Precision Details 2 and Topaz's Gigapixel. So far, I am liking ON1 Resize the best.

Anyway, he started with 8 x 10's and had the same image taken with an iPhone, A7iii, A7Riv and A7Riv in 240 Mpixel mode, and to then have his panel try to decided which ones look the best to worst.

The then simulated a 16 x 20 by cropping the originals and printing more 8 x 10's, and again had his panel judge them.

And he did the same with 32 x 40 and 64 by 60, always just printing 8 x 10's of smaller and smaller crops.

The results sorted themselves out as expected.

Now what would be interesting to add to this would be to resize images and put them in the mix for the panel. For example, if the A7iii is resized 200% and the A7Riv is not resized, the 240 Mpixel version is not resized also, how would the panel sort the resultant 8 x 10's not knowing what produced the image?

I suspect that the resizing would bump up the standing of the A7iii as long as pixel peeping is not possible. But the panel was only holding 8x10 prints, so they are limited in how close they could inspect the picture.

Just print big and see for yourself. Tony is comparing pixels only, and not taking the printing process into account, nor close/far viewing.

I printed an image with the A7rII (42Mp) at roughly 4'x6' and it hangs in the dining room (two panels).

Standing back, you'd look at the image, and details don't matter too much, as you consider the composition.

Standing closely, you can see the many sharp details, and it does impress.

I have printed large panels before with lower res sensor cameras, and yes, the details are visible close up.

As to large prints, you can easily go down to 150dpi, sometimes even to 75dpi, without distorting the 'feeling of sharpness' when viewing from a distance. Closeup, this is not always true.

I would use a 300dpi as a factor to calculate a basic size, and allow a 150dpi to see if I can get larger without a major loss of quality (not, the printer will print at 300dpi anyways, and will 'sharpen' the image in doing so).

At 9504x6336, you are talking:

  • 31"x21" at 300dpi
  • 63"x42" at 150dpi
  • 126"x84" at 75dpi
    (or roughy 'around' 3x2 feet, 5x4 feet, and 10x7 feet).

Do the same for the 24Mp, and you'll get, at 6000x4000,

  • 20"x13" at 300dpi
  • 40"x26" at 150dpi
  • 80"x53" at 75dpi
    (or roughy 'around' 1.5x1 feet, 3x2 feet, and 5x4 feet, i.e. 'one size down').

In other words, simply translate the 9504x6336 vs 6000x4000 as a 1.4x linear, or almost 2x area differences.

Being able to print twice-as-large is significant. Only if you cannot get close to a large print, then the higher resolution may not matter. Otherwise, it will always be more impressive - assuming that you did capture enough detail at full (pixel peeping) resolution.

As a corollary: a friend of mine printed a 6Mp image at 3'x4' - it is a portrait of his daughter when young. The printed image is beautiful, and resolution does not matter, as the background is OOF, and printer process sharpened the portrait lines just beautifully. In fact, the lower resolution works almost as a 'smoothing' filter for the skin textures. But yeah, you'd best look at it from some distance...

Henry,

Everywhere you mention dpi (dots per inch) it should be ppi (pixels per inch).

dpi has to do with printers only.

S

Your point is valid, the printer will (usually) print at 300 or 600 dpi anyways, and interpolate data when possible. The actual content would be measured in how much you stretch the pixels per inch (how low).

Most Epson printers print at 1440 or 2880 dpi. Often they print at both of those at the same time, one vertically and one horizontally. The halftoning software in the driver operates on a 360 or 720 ppi image.

A 300 or 600 dpi printer may be okay for text and binary images, but not for contone ones like photographs.

In an inkjet printer, the resolution of the marking engine is specified in dpi. The resolution of the contone image is specified in ppi. The contone image must be halftoned before being sent to the marking engine.

Jim

Here is a dpi calculator: https://www.pictorem.com/dpicalculator.html

I think that you are referring to photo-printers, I am not, I am referring to large print setups.

But yeah, in Tony's case, a higher resolution printer will affect the outcome, I think.

If you print on canvas, you cannot go to such high resolution anyways, canvas printers typically print at a lower dpi than paper printer.

Here is a 4'x6' two-panel which we printed (full image res 42Mp). If you look at the (extreme) close-ups below, you can see the canvas texture.

And two details from the right panel: foreground

And background:

In Tony's example, such close-ups would be rather misleading, I think...

-- hide signature --

Cheers,
Henry

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