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Resizing software.  Rate Topic 
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Posted by MaxSouthOz: Fri Apr 4th, 2014 02:52 1st Post
I'm not sure if this will work, but here's a shot I've taken after resizing . . .

Attachment: iii.jpg (Downloaded 32 times)



Posted by MaxSouthOz: Fri Apr 4th, 2014 02:55 2nd Post
Nope it's not going to work.

The file size is too big for the forum, but it starts out as a beautiful clear, crisp image and then when its resized, it loses clarity as above.

FYI, it's a shot of the underneath of my model railway layout.

My forum is the same as this one.  UlraBB.

Intuitively if the image is reduced in size, the clarity shouldn't be affected - or should it?



Posted by jk: Fri Apr 4th, 2014 03:32 3rd Post
Well it depends on the parameters you use for the resize.

With what software and how are you doing the resizing?

How big is the original file?



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Posted by MaxSouthOz: Fri Apr 4th, 2014 03:41 4th Post
Typically 4928 x 3264  6.04 mb, Jonathon.

I resize to 800 x 600  400 kb

I've been doing some Googling.  Apparently the image suffers quality loss no matter whether you up size or down size.

Counter-intuitive?



Posted by jk: Fri Apr 4th, 2014 03:44 5th Post
If you resize to 1024 x 800 or what I do is constrain Long side to 1000 and then resize it then it comes down to a very small size.

Here is an image from my Fuji XE1 16MP and the orginal jpg is 13.2Mb so the resulting resized image is 227kb which is 1/60

Attachment: XP1-1-4149aa-pp-web.jpg (Downloaded 30 times)



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Posted by MaxSouthOz: Fri Apr 4th, 2014 04:08 6th Post
Excellent.  So instead of selecting 800 x 600 from the options, I make the long side 1000 and let the software work the rest out?



Posted by Eric: Fri Apr 4th, 2014 06:11 7th Post
Conventional wisdom would say that you never down or up sample in one go.

I have always avocated restricting sampling to no more than 50% in each step.

20mb > 11mb > 5.5mb > 3mb > 1.7mb > 1mb

You give the algorithm less of a challenge in deciding what to dump or dither.

It might be tedious doing this manually but I have a CS Action that does this sequentially in a few seconds.




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Posted by MaxSouthOz: Fri Apr 4th, 2014 08:01 8th Post
Thanks, Eric.

I tried going to 1000 as Jonathon suggested and it made an improvement.

I'm going to re-visit it tomorrow and do as you suggested.

Is it necessary to save the image between steps - or can I just step it down inside the editing software?



Posted by jk: Fri Apr 4th, 2014 08:45 9th Post
Eric wrote: Conventional wisdom would say that you never down or up sample in one go.

I have always avocated restricting sampling to no more than 50% in each step.

20mb > 11mb > 5.5mb > 3mb > 1.7mb > 1mb

You give the algorithm less of a challenge in deciding what to dump or dither.

It might be tedious doing this manually but I have a CS Action that does this sequentially in a few seconds.



Hmm.. Didnt know that but the logic is good.



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Posted by richw: Fri Apr 4th, 2014 09:20 10th Post
I don't really do much resizing but I do own perfect resize - which one software bought from genuine fractals - meant to be the best.



Posted by amazing50: Fri Apr 4th, 2014 14:05 11th Post
richw wrote: I don't really do much resizing but I do own perfect resize - which one software bought from genuine fractals - meant to be the best.Onone is now the owner and distributor of genuine fractals software.



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Posted by MaxSouthOz: Fri Apr 4th, 2014 16:12 12th Post
That's going to be a big help, Ed.

I typically take up to 15 batches of up to 20 shots per day.  The batches are run through Helicon focus and then resized for my forum gallery.

Faststone allows me to resize with a few clicks, so if I don't have to save the image between steps, it shouldn't be too onerous.

Thanks again.



Posted by MaxSouthOz: Fri Apr 4th, 2014 17:45 13th Post
Well, I and a couple of others have run some tests with my original shot.

Starting at 4928 x 3264, we started down sizing to 3000 2000 1000 and 800 long side measurements.  We could see no improvement between stepping it down and going straight to 1000 or 800.

I then tried sharpening the image by the tiniest amount which would show a change and it looks 'orrible - very grainy.

I'm beginning to think that the D 7000 won't produce an image good enough to cope with any downsizing.  My wife has a D 90.  I might give that a go and see if it's any better.

Attachment: Sharpened.jpg (Downloaded 19 times)



Posted by amazing50: Fri Apr 4th, 2014 23:19 14th Post
The problem isn't your D7100, but the software.

Different programs use different algorithms to reduce the image.

Taking a D600 native 6016x4016 @ 300DPI, 20.05x13.39 inches, 24.16 MP, and reducing it to 6x4 1800x1202 2.1MP @300DPI louses over 90% of the pixels.

If this 6x4 is printed at 6x4 it will look as good as the original printed at 20x 13.39 on the same printer with the same settings.

If the reduced 6x4 pic is printed or displayed on screen, at a larger size it will show loses.



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Posted by MaxSouthOz: Sat Apr 5th, 2014 00:39 15th Post
Thanks. 



Posted by amazing50: Mon Apr 7th, 2014 03:25 16th Post
jk wrote: If you resize to 1024 x 800 or what I do is constrain Long side to 1000 and then resize it then it comes down to a very small size.

Here is an image from my Fuji XE1 16MP and the orginal jpg is 13.2Mb so the resulting resized image is 227kb which is 1/60

Amazing how much detail is still visible with only 1/60 of the pixels.



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