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Save for web - resize or resample?

Discussion in 'Image Processing' started by RetroBoy, Apr 20, 2012.

  1. RetroBoy

    RetroBoy Mu-43 Regular

    Just wonderin how you guys downsize and save your shots for viewing here or Flickr etc.

    I usually process my keepers in Photoshop to my liking and then just re-save them as a jpeg. Then if I want to upload an image, I'll open it in my default viewer (which is Irfanview) resize it to 1024 pixels wide and "save as" to a different folder.

    Now there's two options in Irfanview- Resize or Resample.

    When upsizing small files I use choose resample which uses the Lanczos filter to interpolate and smooth out the apparent resolution. It does a great job.

    However, I'm not sure the best way to downsample and still retain sharpness.

    I've been using the Lanczos filter to resample down, but notice the pics lose some of their sharpness - like I've added a slight blur.

    So I've tried plain resize instead, but some pics look a bit too pixellated.

    I know I should probably learn to sharpen for the web or something.
    Is this necessary? What do you do??

    Here's a couple of pics to show the difference between Irfanview's Resize and Resample at 1024 wide.

    Other than cropping, tweaking contrast and changing the size, these are straight ooc jpegs - standard E-PL2 sharpening.


    <a href="http://www.flickr.com/photos/retroboy07/7096143113/" title="P4200977resize by Retro.Boy.07, on Flickr">
    Subscribe to see EXIF info for this image (if available)
    "1024" height="768" alt="P4200977resize"></a>


    <a href="http://www.flickr.com/photos/retroboy07/6950072192/" title="P4200977resample by Retro.Boy.07, on Flickr">
    Subscribe to see EXIF info for this image (if available)
    "1024" height="768" alt="P4200977resample"></a>
  2. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
  3. tdekany

    tdekany Mu-43 All-Pro

    Dec 8, 2011
    Dave, both are exceptional pictures, but the first one really does it for me.
  4. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    I keep an uncompressed master, in my case in my Aperture library. When I need to use an image for something I go to the master and do the appropriate resizing and compression. Compressing an image more than once even without resizing will cause a quality reduction. This applies to jpegs, there are some lossless compression types that can be used instead.
  5. RetroBoy

    RetroBoy Mu-43 Regular

    Thanks for the replies and for resurrecting this query.

    I'm mostly wondering whether people choose plain "Resize" - which just bins any unwanted pixels,
    or "Resample" - which interpolates or smoothes out any jaggies.

    Until now I've chosen to resample - but some sharpness is inevitably lost.

    How do you all save your big files for the web??
  6. jff1625

    jff1625 Mu-43 Regular

    Jan 14, 2012
    You mentioned you use photoshop, so try CTRL-ALT-SHIFT-S, "save for web". Or maybe it's CTRL-ALT-SHIFT-W, I can't remember. I use it so much my hand just naturally lands on the keyboard in that position.
    Incidentally that's my main reason for disliking Macs - you can't hit save-for-web with one hand without some serious contortion on a Mac keyboard layout.
    Back to topic:- save-for-web lets you choose an output size and gives you a range of resizing algorithms to choose from, including some with sharpening built in. Simples!
    You could also try running an unsharp-mask filter over the image before resizing.

  7. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    All the applications I have that will resize an image use some sort of interpolation algorithm. I've never heard of one that simply throw away excess pixels.

  8. gsciorio

    gsciorio Mu-43 Top Veteran

    Dec 29, 2011
    Miami, FL
    I too don't care much for post work anymore so I use Lightroom and C1Pro. Both are fast and of the highest quality for raw files and it shows in the output.

    When I do need to save anything other then photographs I use Save For Web from PS 5.5
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