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Resize to 30% comparison

Discussion in 'General Technical Discussion' started by Ron Reznick, Apr 9, 2005.

  1. Here is a comparative analysis of four methods for resizing a D2x image down to web-size. Three algorithms used in Photoshop, plus a Capture resize, with appropriate USM applied as noted:

  2. I assume you are leaving us to draw our own conclusions. For me personally I like PS CS (bicubic smoother). I don't know what Fred Miranda's WP Pro software uses but it seems to work for me and saves me a lot of time. Thanks for sharing your comparison information and I assume you will also share your conclusions after we have had an opportunity to post.
  3. Flew


    Jan 25, 2005
    Excellent stuff Ron. There's only one problem; now I'm going to have to repeat this whole thing and compare the results to the FM Resize Pro plug-in that I bought recently. :?

    So far, I'm really enjoying my switch to PS CS, and Fred's plug-ins have greatly eased the start-up pain. There is no doubt in my mind that I'm getting much better results with PS, so it has been well worth the effort so far.

    Thanks for posting!!

  4. PJohnP


    Feb 5, 2005
    Ron :

    Excellent work. Your contributions in looking at the science of the digital photograph never cease to amaze me. This kind of methodical comparison is essential for all of us. Thank you.

    And the thing that you never note is which of these that you most favour...

    John P.
  5. I figure it's better to allow you to make your own decisions based on the information presented, rather than telling you... however, I think that the Capture resize is the finest overall (costing a step in post though), with the Bicubic Sharper coming in a close second.

  6. MontyDog


    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
  7. Hi Paul,

    That third shot (landscape) is a tricky composition. You happened to have the camera exactly level with regards to the plane of gravity (assuming the buildings in the background were level, as they most likely were), but the buildings are so distant that the viewer's natural horizon is not referenced to them at this size at least. The result is that the entire composition looks rotated counterclockwise. In a large print it would possibly become obvious that you were not rotated (if the buildings were presented large enough to become a visual reference), but in most presentations that shot should have been acquired with a clockwise rotation for a better visual orientation, or rotated in post.

    As far as focusing mode selections are concerned (based on Continuous Servo):

    Single-Area is for static subjects, or moving subjects which you can keep within the focusing reticle;

    Single-Area Dynamic is for subjects which you can acquire within a reticle but you want to be able to track the subject as it moves off the reticle to other areas in the composition (rapidly- and erratically-moving subjects, or moving subjects to be acquired in a fixed composition);

    Group Dynamic is for situations where you want to pull a subject or group of subjects out of a featureless (or nearly featureless) field and track them within a small area defined by the group.
    (1) is for situations when you have subjects that are moving somewhat erratically, but you can keep them within a small area defined by the group.
    (2) is for use when you know they are going to be moving either horizontally or vertically within the defined frame.
    Center-acquisition mode is like Single-Area, but with the addition of Dynamic tracking with grouped sensors.
    Closest subject will select the closest subject within the group and track it within the selected group of sensors;

    Dynamic AF with closest subject priority is essentially idiot mode, but it is useful when acquiring a subject in a low-to-medium contrast scene when you know your subject is going to be the closest strongly-contrasting thing in the frame. This can be a problem in a busy, high-contrast background such as a field of flowers, a water scene with whitecaps, or with a background of trees against the sky where the subject does not have higher contrast than the rest of the scene, or when there are moving subjects in a group (the camera may not be able to select your desired subject), but in some cases it can make the job of acquiring a lock easier (as can Group Dynamic).

  8. Hi, Ron, long time no say "Hi"....

    In looking at these 4, the first thing that caught my eye was the eye, and I like the way the eye looks best in the NC rendition. But in some ways I like the "body treatment" better in the BiCubic. What is it that you key in on for juding this? Is is the body markings, the eye, something else I am not seeing?

  9. Iliah


    Jan 29, 2005
    Bill, have you double-clicked the embedded image to view it full size?
  10. No, I hadn't, but it sure looks quite different when I do. I am getting ready to head off for today's Indoor Football Game, I'll have to examine this more later. I am quite puzzled as to why it looks so different, however.
  11. MontyDog


    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
  12. genec57

    genec57 Guest

    Me and or my eyes must be getting old but I will be darned if I can see any difference in them. Would someone like to point out the obvious to me? :) 
  13. Hi Gene,

    Open the full-size image (it's a little larger than the visible image, and the resizing algorithm used on this site messes with the detail enough that it obscures information you need to see).

    Note the contrast, dimensionality and definition of the eye, beak and breast and wing feathers. Also, check the curved, rising reed in the foreground that is in the focused plane. Note the dimensionality and definition of the head at the transition to the background.

  14. Ron, when you're resizing in PSCS, are you using steps or one big jump down to 30%? I've been resizing my pics down in 10 steps and have been pleased with results but always open to more info! My personal preference on these is the Bicubic sharper but then again, I've always been a fan of really crisp pics. BTW Ron, after attending your session last summer led me to grab a BenQ 23" LCD - LOVE the huge pics! Thanks for helping me part with my coins :( 
  15. genec57

    genec57 Guest

    Thanks, Ron, now I see it.
  16. Hi Sandi,

    I upsample in steps, but I downsample using integer ratios (80%, 75%, 66%, 50%, 33%, 30%, 25%, or combinations thereof). If I go to 50%, it's in one step. Sometimes, to get a required size it is better to go with a two or more stage reduction (e.g. 80%, 66%, 50%). The idea is that you don't want to attempt to throw away fractional pixels... the algorithm has to invent pixels when you do that.

  17. Hi Ron,

    At what point do you apply the USM? Is it before or after the resize?


  18. After the resize... in Capture you use the Size/Resolution dialog (it's not capable of working by percentage, so you type in the correct pixel resize for the percentage), then apply USM as required. Photoshop allows resizing by percentage and algorithm. Do that first, then USM to taste.

  19. Ron, thanks for that info. One thing I question: is 66% not really 66.666667% thereby creating fractional pixels? Would I best stick to 50% of 50% etc instead of using the 33% and the 66% (not looking for mathematically equivalents, just using these numbers as examples)? You're such a wealth of info - keep that brain working so ours don't have to! *wink*
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