1. Computer problem? Tech Support Guy is completely free -- paid for by advertisers and donations. Click here to join today! If you're new to Tech Support Guy, we highly recommend that you visit our Guide for New Members.

Need better understanding of pixels and interpolation.

Discussion in 'Digital Photography & Imaging' started by Alex Ethridge, Sep 21, 2003.

Thread Status:
Not open for further replies.
Advertisement
  1. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

    Joined:
    Apr 10, 2000
    Messages:
    9,033
    I have a camera that lists its maximum resolution as 2832 x 2128 (interpolated) and its effective pixels at 3.1 million, but doesn't list a non-interpolated resolution. Now, I do have an understanding of interpolation and I see it as being a way of really just faking a higher resolution; but, I would like to know more about actual resolution as opposed to interpolated.

    One of the things that I am wondering about is the size (in Megs) of a non-interpolated image as opposed to an interpolated image. For instance, what if I chose to make all my pictures at the camera's actual resolution as opposed to the camera's iterpolated resolution. There are plenty of programs available that could interpolate it to a higher resolution later, outside the camera. This would have the benefit of allowing me to record only the camera's actual image and I would have the added benefit of getting more images onto a single memory card. Later, those same images could be interpolated up if I wanted.

    What are the pros and cons of this and where can I find some technical explanations of this on the internet?
     
  2. kiwiguy

    kiwiguy

    Joined:
    Aug 17, 2003
    Messages:
    17,584
    It sounds like you have a FujiFilm FinePix, possibly an S602Z?

    Look on camera review sites (dpreview.com etc) for in depth analysis.

    In-camera interpolation is apparently better than external in that case, so I have read. I tend to use the highest resoulution, and bring the file size down by selecting higher compression. This is the view of experts on some sites, as being the better choice.

    My images end up around 1.2 MB per photo. I have a 1 GB memory card, so size is not really an issue.

    As to the selection of resolution to match the "native" resolution of the CCD, consider that the images from all digital cameras are interpolated to some extent internally to produce a full colour image from the 3 colour mask on the CCD.

    Select the resolution that gives the best result. Try zooming the resulting image to see where the optimum is. I think you will fine in-camera interpolation does work better than you expect.
     
  3. Davey7549

    Davey7549

    Joined:
    Feb 28, 2001
    Messages:
    11,584
  4. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

    Joined:
    Apr 10, 2000
    Messages:
    9,033
    So far, I've found only two sites that discuss in-camera as opposed to out-of-camera interpolation. Both have stated the out-of-camera interpolation is superior.

    One was a ZDNet site; but, I have forgotten where the other site is. They both said about the same thing, though. I saved the web page, itself, but, I don't know the actual web address anymore. Here is the pertinent text:
    I guess it is a subjective question and it appears that some might prefer one over the other; however, I'm still researching it for my own final preference to come out of it all.

    Interpolation softens images and I don't like soft images. The greater the interpolation, the softer the image. The only way to solve that problem is optical resolution high enough to produce a sharp image large enough to need no interpolation. But, in digital photography, that is not even near possible yet.

    What I am after right now is to determine whether I want to shoot with interpolation or to shoot at the camera's optical resolution and interpolate later. There are great advantages to that. With a 1-Gig CF card, I can place about 60 images without compression (compression being another factor that degrades images). But, I could place approximately 330 images at optical resolution and interpolate later. And, according to the experts, interpolating later in Adobe Elements or PhotoShop is actually a higher-quality interpolation.
     
  5. slipe

    slipe

    Joined:
    Jun 27, 2000
    Messages:
    6,832
    You seem to have reason to not share what camera you are using, but Fuji is the only one I know of that used that smoke and mirrors trick from 3 to 6Mp. Some of the things you list are not the same as the standard Fuji 602Z. You say you can get about 60 uncompressed 6Mp interpolated images on a 1Gig card which is about right for the Fuji 602Z (57). But there is no mode that will give 330 images at optical resolution. The choices with the Fuji 602Z are fine JPG compression of 6Mp interpolated giving about 400 images or fine with the 3Mp uninterpolated images giving nearly a thousand shots per card. It doesn’t equate to the S5000 model either which extracts the 6Mp image in raw and gives many more per card.

    The Fuji has a really bad feature built into the 602. You can only extract a TIFF if you use the full 6Mp interpolated resolution (at least it was that way with the standard 602Z). If you use the effective pixels and don’t use in-camera interpolation you have to use a compressed format. If you have a Fuji or something that works the same way, the camera does have an advantage interpolating the image. If you extract a 3Mp image (2048 X 1536) it is compressed. If you upsample it yourself you are enhancing the compression artifacts where the camera can upsample the raw image. It should give better results.

    I downloaded the 6Mp and 3Mp compressed images from Phil Askey’s 602Z review and upsampled the 3Mp to 6Mp. The image upsampled in the camera was better. That is purely a result of upsampling a compressed image compared to the camera being able to upsample a raw image though. If whatever camera you have allows you to extract a 3Mp raw or TIFF image I would think you would do at least as well upsampling in the computer.

    If I had a Fuji 602Z I would probably save as fine with 6Mp (2832 X 2128) considering the size of your card. TIFF is an impractical format except for very special shots. Fine is not “softer” in the sense that an upsampled image is softer. There are just slight compression artifacts you can see at high magnification.

    You might try upsampling some 3Mp images and comparing them yourself. Purists claim the Lanczos (Irfanview, etc) filter is a little better than bicubic in Photoshop – I have done tests and can see a slight difference but one doesn’t seem superior to the other. You might try it with several images as the results can vary. You would have to do both extracting JPGs.

    I personally wouldn’t normally use the space to extract a 6Mp TIFF – I presume about 18Mb each. Raw format takes about a third the space and is a better image than a TIFF, but you don’t have that choice with the 602 – only with the 5000. But if you are careful to save the originals and not amplify the compression artifacts with multiple compressions it is really hard to see the difference. My 5Mp camera doesn’t have a very good buffer and I shoot high quality JPG in fast moving situations. It is very hard to see the difference between the fine JPG and the raw images converted to 48bit TIFF – even printed at 13 X 19 on a good printer. They definitely aren’t “softer”. Compression artifacts sometimes give a sharper looking image if not viewed at high magnification.
     
  6. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

    Joined:
    Apr 10, 2000
    Messages:
    9,033
    Thanks for the comprehensive reply. I don't understand a lot of it because I am new to digital. (Ask me about a Rapid Omega Press camera and I'll tell you a lot.)

    It is the S602, and I am disappointed to learn it seems to have no setting for an uninterpolated, uncompressed 3-Meg image.

    As for the quantity of pictures per 1-Gig disk, those are only guesses. I am currently shooting TIFFs, approximately 17 Megs each. I do that only because I never need more that one memory card will hold; however, on occasion, I do go to JPG to give me more shots when I think I might need it.
     
  7. hewee

    hewee

    Joined:
    Oct 26, 2001
    Messages:
    57,791
  8. Sponsor

As Seen On
As Seen On...

Welcome to Tech Support Guy!

Are you looking for the solution to your computer problem? Join our site today to ask your question. This site is completely free -- paid for by advertisers and donations.

If you're not already familiar with forums, watch our Welcome Guide to get started.

Join over 733,556 other people just like you!

Loading...
Thread Status:
Not open for further replies.

Short URL to this thread: https://techguy.org/166373

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice