Downsizing / Downsampling / Resizing or whatever you call it...

Started Dec 11, 2013 | Discussions
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Elyharbour
Elyharbour Senior Member • Posts: 1,516
Downsizing / Downsampling / Resizing or whatever you call it...

OK guys...as some of you know I've been down-(sampling or -sizing) my XF1 HR 12MP JPEGs to be directly comparable with the 6MP EXR hardware images for forum comparison. I usually do this in  FastStone Image Viewer, but sometimes in Lightroom.

In FastStone there are various resizing methods (Lanczos 2, 3, etc) and Kim Lettermann recently mentioned bicubic. What are the pros and cons of these methods? Are there any real differences for the sorts of images we're talking about here in the forums?

Thanks.

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PAUL TILL
PAUL TILL Veteran Member • Posts: 9,285
Re: Downsizing / Downsampling / Resizing or whatever you call it...

I always use Bicubic Sharper.

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The 10% Rule:
You Must Be 10% Smarter Than The Equipment You're Operating

Elyharbour
Elyharbour OP Senior Member • Posts: 1,516
Re: Downsizing / Downsampling / Resizing or whatever you call it...

Nice looking image you're working on there...

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CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Downsampling / Resizing or whatever you call it...

Elyharbour wrote:

In FastStone there are various resizing methods (Lanczos 2, 3, etc) and Kim Lettermann recently mentioned bicubic. What are the pros and cons of these methods? Are there any real differences for the sorts of images we're talking about here in the forums?

Lanczos3 (also called Sinc) is the best algorithm for downsampling if you don't change aspect ratio. If you change aspect ratio, Bicubic (also called Cubic) works better.

I have not investigated upsampling (seldom needed) but believe the answer is is not the same as for downsampling.

There are many other considerations besides the downsampling algorithm, such as JPEG encoding afterwards.

Downsizing is a corporate euphemism for firing employees.

CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Downsizing / Downsampling / Resizing or whatever you call it...

PAUL TILL wrote:

I always use Bicubic Sharper.

Some pundits say it's better to use Bicubic, then Smart Sharpen.

I don't use Photoshop and have no opinion one way or the other.

jcmarfilph Veteran Member • Posts: 7,592
Re: Downsizing / Downsampling / Resizing or whatever you call it...

Bicubic for me...

Here are some results showing superiority of Lsize versus upsampled MSize

Both downsampled to 1920px and LSize is still superior

-=[ Joms ]=-

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Lloydy
Lloydy Forum Pro • Posts: 18,890
Elyharbour ...

... To size an image down, use Bicubic Sharper.

To size an image up, use Bicubic Smoother.

Here is an article about sizing up - Resizing an image - Up

Elyharbour wrote:

OK guys...as some of you know I've been down-(sampling or -sizing) my XF1 HR 12MP JPEGs to be directly comparable with the 6MP EXR hardware images for forum comparison. I usually do this in FastStone Image Viewer, but sometimes in Lightroom.

In FastStone there are various resizing methods (Lanczos 2, 3, etc) and Kim Lettermann recently mentioned bicubic. What are the pros and cons of these methods? Are there any real differences for the sorts of images we're talking about here in the forums?

Thanks.

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Cheers, Dave

CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Elyharbour ...

Lloydy wrote:

... To size an image down, use Bicubic Sharper.

To size an image up, use Bicubic Smoother.

Here is an article about sizing up - Resizing an image - Up

I don't really give a darn what everybody decides to do, but Bicubic (whether Sharper or Smoother) is definitely not the best method. Here are some examples:

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/down_sample.htm

Elyharbour
Elyharbour OP Senior Member • Posts: 1,516
Re: Downsampling / Resizing or whatever you call it...

CAcreeks wrote:

Elyharbour wrote:

In FastStone there are various resizing methods (Lanczos 2, 3, etc) and Kim Lettermann recently mentioned bicubic. What are the pros and cons of these methods? Are there any real differences for the sorts of images we're talking about here in the forums?

Lanczos3 (also called Sinc) is the best algorithm for downsampling if you don't change aspect ratio. If you change aspect ratio, Bicubic (also called Cubic) works better.

I have not investigated upsampling (seldom needed) but believe the answer is is not the same as for downsampling.

There are many other considerations besides the downsampling algorithm, such as JPEG encoding afterwards.

Downsizing is a corporate euphemism for firing employees.

Lanczos3 is the default in FastStone, so I guess I'll just leave it as is. I tried the bicubic today and Lanczos2, and couldn't honestly see any difference, but neither did I really know what I was looking for.

PS - I now know not to call it down-sizingĀ 

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Lloydy
Lloydy Forum Pro • Posts: 18,890
CA ...

... Interesting article but I wonder how long back it was written and which version of CS ?

I downloaded the Rings Gif and resized, up and down, using Bicubic Sharper and Bicubic Smoother and had none of the issues described in the article. I'm using CS6.

I would encourage others to try the same with their own editing software and see what results they get.

CAcreeks wrote:

Lloydy wrote:

... To size an image down, use Bicubic Sharper.

To size an image up, use Bicubic Smoother.

Here is an article about sizing up - Resizing an image - Up

I don't really give a darn what everybody decides to do, but Bicubic (whether Sharper or Smoother) is definitely not the best method. Here are some examples:

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/down_sample.htm

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Cheers, Dave

CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Dave...

Excellent test!  Did you start with the large version that was linked into the article?  It is possible that Photoshop resize has improved. I have not used Photoshop since CS2, but my daughter has CS5 on her Mac and I could try it to compare.

Lloydy wrote:

... Interesting article but I wonder how long back it was written and which version of CS ?

I downloaded the Rings Gif and resized, up and down, using Bicubic Sharper and Bicubic Smoother and had none of the issues described in the article. I'm using CS6.

I would encourage others to try the same with their own editing software and see what results they get.

CAcreeks wrote:

Lloydy wrote:

... To size an image down, use Bicubic Sharper.

To size an image up, use Bicubic Smoother.

Here is an article about sizing up - Resizing an image - Up

I don't really give a darn what everybody decides to do, but Bicubic (whether Sharper or Smoother) is definitely not the best method. Here are some examples:

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/down_sample.htm

-- hide signature --

Cheers, Dave

Lloydy
Lloydy Forum Pro • Posts: 18,890
CA ...

... Yes, I downloaded the 1000 x 1000 pixel image and then played around with sizing up/down. Would be interesting to see how CS5 fares, or even the latest LR.

CAcreeks wrote:

Excellent test! Did you start with the large version that was linked into the article? It is possible that Photoshop resize has improved. I have not used Photoshop since CS2, but my daughter has CS5 on her Mac and I could try it to compare.

Lloydy wrote:

... Interesting article but I wonder how long back it was written and which version of CS ?

I downloaded the Rings Gif and resized, up and down, using Bicubic Sharper and Bicubic Smoother and had none of the issues described in the article. I'm using CS6.

I would encourage others to try the same with their own editing software and see what results they get.

CAcreeks wrote:

Lloydy wrote:

... To size an image down, use Bicubic Sharper.

To size an image up, use Bicubic Smoother.

Here is an article about sizing up - Resizing an image - Up

I don't really give a darn what everybody decides to do, but Bicubic (whether Sharper or Smoother) is definitely not the best method. Here are some examples:

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/down_sample.htm

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Cheers, Dave

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Cheers, Dave

Futax Regular Member • Posts: 379
Re: Downsizing / Downsampling / Resizing or whatever you call it...

Lanczos certainly beats the other algorithms when it comes to the problem of aliasing when you downsample:

http://therefractedlight.blogspot.co.uk/2010/12/problem-of-resizing-images.html

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Elyharbour
Elyharbour OP Senior Member • Posts: 1,516
Re: Downsizing / Downsampling / Resizing or whatever you call it...

Futax wrote:

Lanczos certainly beats the other algorithms when it comes to the problem of aliasing when you downsample:

http://therefractedlight.blogspot.co.uk/2010/12/problem-of-resizing-images.html

An excellent article. Now I understand what is going on. Thank you.

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dick
dick Veteran Member • Posts: 5,227
Re: Downsizing / Downsampling / Resizing or whatever you call it...

A bit off subject, but I think RE-SIZING is the appropriate term.

My dictionary defines RE as, "again: for a second time." That makes sense, because the program has already set the size and we are sizing it again, thus RE-sizing. And that applies to both ways, up and down.

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CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Resize vs Resample

Here's what the ImageMagick options say:

  • -resample geometry : change the resolution of an image
  • -resize geometry :  resize the image

Can you explain which does what?

dick wrote:

A bit off subject, but I think RE-SIZING is the appropriate term.

My dictionary defines RE as, "again: for a second time." That makes sense, because the program has already set the size and we are sizing it again, thus RE-sizing. And that applies to both ways, up and down.

CAcreeks
CAcreeks Veteran Member • Posts: 8,933
A good comparison of resampling products

This page was difficult to find with Google search, but seems like it might be helpful for all. At the bottom is a clickable image to compare results from 11 different downsampling methods.

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/example1.htm

Nicolas Robidoux Forum Member • Posts: 84
Re: Downsizing / Downsampling / Resizing or whatever you call it...

For reducing the size of an image, I highly recommend EWA (Elliptical Weighted Averaging) with slightly deblurred (meaning that the filter's extent is "shrunk" from the unwindowed version that's theoretically ideal from a frequency response viewpoint) 3-lobe Jinc-windowed Jinc filtering done through linear light (XYZ or linear RGB with sRGB primaries). Details here: http://www.imagemagick.org/Usage/filter/nicolas/

CAcreeks
CAcreeks Veteran Member • Posts: 8,933
Re: Downsizing / Downsampling / Resizing or whatever you call it...

Do you mean "Jinc-filtered Sinc filter" ?

convert {input} -colorspace RGB +sigmoidal-contrast 7.5 \
-define filter:window=Jinc -define filter:lobes=3 \
-resize 500% -sigmoidal-contrast 7.5 -colorspace sRGB {output}

Nicolas Robidoux wrote:

For reducing the size of an image, I highly recommend EWA (Elliptical Weighted Averaging) with slightly deblurred (meaning that the filter's extent is "shrunk" from the unwindowed version that's theoretically ideal from a frequency response viewpoint) 3-lobe Jinc-windowed Jinc filtering done through linear light (XYZ or linear RGB with sRGB primaries). Details here: http://www.imagemagick.org/Usage/filter/nicolas/

Lloydy
Lloydy Forum Pro • Posts: 18,890
CA ...

... If you look at the bottom of the page it says copyright 2004.

My concern with these examples is that image editing software has progressed in leaps and bounds in the past ten years and posting tests as old as that one do not reflect today's reality.

As mentioned prior, I downloaded the Gif file for the original tests shown and replicated the tests done by the author.

My results showed none of the issues reported.

Post current data please so as not to mislead the discussion.

CAcreeks wrote:

This page was difficult to find with Google search, but seems like it might be helpful for all. At the bottom is a clickable image to compare results from 11 different downsampling methods.

http://bvdwolf.home.xs4all.nl/main/foto/down_sample/example1.htm

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Cheers, Dave

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