Downsizing Challenge Part 2: The Siemen's Star

[Andrea B.]

The other thread had gotten so long that I thought it best to start a new one.

Recap:  Simone (simsurace) has been helping me with downsizing D810 photos because I have not been happy with results so far when the typical downsizing routines are applied to D810 landscapes. In Part 1, I worked through some examples to convince myself of a few things. In summary:

• My converters play no particular role in D810 landscape downsizing issues. I tested Photo Ninja and NX2.
• It did not particularly matter whether some sharpening was applied prior to my downsizing a D810 landscape.

New:  Simone supplied a Siemen's Star PNG to test downsizing methods. (Thanks again!!) So now I'll run through a few typical downsizing algorithms with that.

Photo 1:  Here is an unresized crop of the center of the Siemen's Star so you can see some of the (false?) detail.
Photo 2: This is an unresized crop of an area to the right of center.

[Frank Fremerey]

A great proof, that downsizing happens in the forum software. What came through of what you posted is some fractal compression algorithm no Simens star:

[Frank Fremerey]

This is a Siemsstar: http://www.ngn-studios.de/uploads/media/Siemensstern.jpg

testing to embed this link:

[Andrea B.]

That is interesting.

My Siemen's Star crop is 406 x 406 pixels and is not downsized by the forum software.
Right click it and select View Image Info. Then look for the pixel dimensions to see 406 x 406.

So what you are seeing - or rather not seeing - is the "compression" from your display resolution.

I am on a Macbook Pro Retina, and I can see every detail.

[Andrea B.]

Well, anyway, onward to the downsizing tests.

I fear this may not work out well for anyone not having a high resolution display, but I will trudge onward.

[Andrea B.]

[LATER EDIT:  I replaced the 1000px resizes with 920px resizes for more useful matching with some later images.]

TEST:  Downsize the 7360 x 4912 px Siemen's Star to 1000px 920px width with no new sharpening after the downsize.

Photo 1 :: Capture NX2 downsize to 1000px 920px width with no new sharpening after downsize.
Photo 2 :: Photo Mechanic downsize to 1000px 920px width with no new sharpening after downsize.
Photo 3 :: Photoshop Elements 11 downsize to 1000px 920px width with no new sharpening after downsize.

CONCLUSION ::
On a Macbook Pro Retina screen, the downsize in Photo 3, made with PSE Bicubic Sharper, retains more center detail.
The downsizes made in NX2 and Photo Mechanic have both lost some center detail.
The Capture NX2 downsize is a bit better than the Photo Mechanic version.
Count the rings from the center to see that the NX2 downsize loses large amounts of detail in the first 3 rings,
while the PhoMechic downsize loses detail in the first 4-4.5 rings.

ADDED LATER:  Actually it is not center detail that we should worry about so much. We know we are going to lose center detail in this kind of star with tiny 1-pixel frequency detail. What happens in the slightly larger areas is what we want to look at I think.
Note :: Be sure to expand your browser so that you can view the full 1000 920 pixel width.
Right-click the photo and select View Image Info to verify this by checking that the displayed dimensions are 1000 x 667 px 920 x 614 px.

[zuglufttier]

I really don't understand what you are trying to proof... There are differences in downsizing algorithms, true. But what else?

Btw: OS X just doubles every pixel on a retina screen on normal settings, it's the same as setting everything to 200% in Windows. You can do that with a lower resolution screen, too.

[Andrea B.]

As stated, I have been unhappy with the downsizing of my D810 landscapes. None of the usual downsizing methods seem to work well for these big files. They turn out blocky or crunchy sometimes.

We all got to talking about it, Simone offered some help and so I decided to test the various downsizing methods to see which one works best for downsizing D810 landscapes which have 36 megapixels and lots of high frequency detail. We have some "accepted wisdom" about downsizing. But is it myth or is it true?

Nothing to prove. Just trying to learn. 

Added a minute later:  I have a Toshiba Windows laptop on which I will also view the results. Our downsizes posted for web display should be viewable with reasonable detail on both types of machines.

[zuglufttier]

Can you provide the Siemens star you used for downsizing? I'd like to try it myself

[Andrea B.]

Simone provided the star here:  https://www.dropbox.com/s/hijmrelhpaesijt/Siemens.png?dl=0

[Andrea B.]

A stepped percentage downsizing has been advocated for better results. Is this a myth or is it true?

TEST:  Using the PS Bicubic Sharper algorithm, downsize the 7360 x 4912 px Sieman's Star in three steps of 50% each to reach a final 922 px width. Compare that to a direct downsize to 922 px.

CONCLUSION:  There is a peculiar asymetric effect in the direct downsize that is not present in the stepped downsize. So the stepped downsize is probably better.

NOTE 1:  You may not be able to see these downsizes well on iPhone or iPad because of the weird way they resize images? And I do not know if the details will show up on a non-Retina screen?? You will have to let me know. I added a blowup of part of the two downsizes in hopes you can see some details.
NOTE 2:  Be sure to expand your browser to display the full 920 px width.

PHOTO 1: Stepped downsize.
PHOTO 2: Direct downsize.

Photo 1 Blowup
Photo 2 Blowup

[Frank Fremerey]

I cannot see any of them in a sensible way,
Neither on my 24 inch IPS with 1920x1200 qpixels
Nor on my 5.5 inch AMOLED with 1280x786 qpixels

This might be interference patterns with the screen resolutions
and they change when I zoom the pictures on the screen

Sooo.

With resizing as with sharpening your target medium is
the important  value.

My screens are not able to reproduce your Simensstars

But they are able to reproduce the Simensstar I posted.

Food for thought?

[Andrea B.]

Yes, the target medium is important.

I just changed my Macbook Retina Display size to 1920 x 1200 pixels. The preceding JPGs are crystal clear. So it is apparently not your 1920 x 1200 resolution, per se, which prevents you from seeing the images on your IPS display.

(What does IPS stand for?)

[Andrea B.]

oh In-plane Switching.

[charlie]

The direct downsize has a darker pattern in the center which adds contrast and removes detail. The stepped downsize seems to be the better option because it retains the fine detail.

This is apparent on my 13" Retina MCP, NEC P221w, as well as my cheap Dell 20" 2nd monitor.