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  1. #1
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    What does interpolated really mean?

    Can you go by the interpolated "6megapixles" that they advertise or is that some sort of term for blowing the image up?

    thanks

    bobo

  2. #2
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    Quote Originally Posted by bobo69
    Can you go by the interpolated "6megapixles" that they advertise or is that some sort of term for blowing the image up?

    thanks

    bobo
    interpolated means:

    Definition: interpolated resolution
    The resolution a device can generate by using a process known as interpolation -- estimating intermediate values based on the knowledge of two known values in a sequence.
    (http://www.computeruser.com/resource...hp?lookup=8369)

    In`terīpo`la`ted
    a. 1. Inserted in, or added to, the original; introduced; foisted in; changed by the insertion of new or spurious matter.
    2. (Math.) Provided with necessary interpolations; as, an interpolated table.
    (http://www.thefreedictionary.com/Interpolated)

    Basically, it means taking the picture and stuffing guessed bits in to try to make it bigger.

  3. #3
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    Red face

    Cool, thank you!! (so stay away from it!! )

  4. #4
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    Quote Originally Posted by bobo69
    Cool, thank you!! (so stay away from it!! )
    Good idea

    Watch out for digital zoom as well.

    If you look for actual megapixels and optical zoom, you won't go far wrong

  5. #5
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    It's hard to avoid interpolation...

    Quote Originally Posted by Rhys
    Good idea

    Watch out for digital zoom as well.

    If you look for actual megapixels and optical zoom, you won't go far wrong
    Most digital cameras have a sensor laid out in a "Bayer" matrix, consisting of 50% "green" sites, 25% "red" sites, and 25% "blue" sites. So if you have, say, a 4,000,000 pixel camera, its sensor will really have 2,000,000 "green" sites, 1,000,000 "red" sites, and 1,000,000 "blue" sites. (On the CCD chip, they're really all the same color, but by using filters, manufacturers can make certain sites sensitive only to Green, others to Red, others to Blue) But, when your camera proceeds to create an image file after you've captured a photo, the going starts to get tricky. Each individual pixel of the "4 megapixel" image will need three components of color: A Green byte, a Red byte, and a Blue byte. Since there are 4,000,000 total pixels needed for the entire image, that means that 2,000,000 Green bytes need to be generated, 3,000,000 Red bytes and 3,000,000 Blue bytes also have to be generated. How is that done? It has to be done by interpolation. The only cameras that don't use interpolation for generating images are those that use the 3-layer Foveon technology, where each sensing site contains an R, G, and B layer, stacked so as to be coincident.
    Let a be your umbrella!

  6. #6
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    Smile And ...

    What a great explanation of interpolation by John - highly technical and complicated stuff made to sound simple! Top marks, Brother

    It seems a bit churlish to add more but interpolation is, if I've got it right, one of the main reasons why the traditionalist (film) photographers claim digital imaging isn't "real" photography at all and maybe they've got a point. To a certain degree, the camera isn't really collecting all the information for the final image from the scene in front of it when the shutter release is activated, in the way that a film camera does. It has to use interpolation - or a sophisticated system of guesswork if you want to call it that. Because of that, it could be argued that a lot of the detail is, in effect, "computer generated" and therefore not "real" photography.

    Personally speaking, I think that's a lot of round things but I understand the argument.

    But don't get carried away with worrying about it. As John says, it's the way most digital cameras work.

    What I can't make up my mind about though is the "interpolated 6mp" that you talk about. I think that it means there's a 3mp sensor in the camera which uses interpolation to get an effective 6mp image. But using John's explanation, I now think it could mean that it's a 2mp sensor.

    Help!!
    Bob Patterson

  7. #7
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    Quote Originally Posted by judge9847
    What a great explanation of interpolation by John - highly technical and complicated stuff made to sound simple! Top marks, Brother

    It seems a bit churlish to add more but interpolation is, if I've got it right, one of the main reasons why the traditionalist (film) photographers claim digital imaging isn't "real" photography at all and maybe they've got a point. To a certain degree, the camera isn't really collecting all the information for the final image from the scene in front of it when the shutter release is activated, in the way that a film camera does. It has to use interpolation - or a sophisticated system of guesswork if you want to call it that. Because of that, it could be argued that a lot of the detail is, in effect, "computer generated" and therefore not "real" photography.

    Personally speaking, I think that's a lot of round things but I understand the argument.

    But don't get carried away with worrying about it. As John says, it's the way most digital cameras work.

    What I can't make up my mind about though is the "interpolated 6mp" that you talk about. I think that it means there's a 3mp sensor in the camera which uses interpolation to get an effective 6mp image. But using John's explanation, I now think it could mean that it's a 2mp sensor.

    Help!!
    The way Bayer images are constructed is largely ignored by the "interpolated 6mp output" claim. What they refer to there is that they take a 3mp Bayer picture and blow it up to 6MP.

  8. #8
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    Cool Megapixels and resolution?

    Quote Originally Posted by judge9847
    What I can't make up my mind about though is the "interpolated 6mp" that you talk about. I think that it means there's a 3mp sensor in the camera which uses interpolation to get an effective 6mp image. But using John's explanation, I now think it could mean that it's a 2mp sensor.
    Thanks, Bob. But if you're referring to the Fuji S5000, which has a 3MP sensor that generates 6MP images, i'm not sure it can be characterized as a "Bayer Sensor," though I think it's still true that the 3 million sensing sites are divided 1/2, 1/4, and 1/4 for G, R, and B respectively. I think Fuji, whose sensor is laid out in a diagonal array rather than a square grid, is forced to interpolate to 6MP to "square up" the image. But does it work? Here are three resolution comparison charts from dpreview Phil Askey's review of the Canon S1, the first chart for the (3.2MP) S1, the second for the (6MP) S5000, the third for the (4MP) Panasonic FZ10. Judge for yourself which one has the highest resolution?
    Let a be your umbrella!

  9. #9
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    Smile Still confused a bit

    Rhys, thanks for that but you'll have to forgive me being a bit of a thicko! It comes with age I'm afraid

    What they refer to there is that they take a 3mp Bayer picture and blow it up to 6MP.
    I don't understand what you mean by "blowing up" to 6mp: are you referring to the output of what is the final image which is made bigger simply by increasing resolution or are you saying that interpolation is used to get to the 6mp mark? If that's so, then though I might not have been able to explain it quite like that, it's what I thought I was saying.

    John, there was quite a lot of noise from Fuji about one of their more recent cameras when the informed press were suggesting, that despite their claims, all Fuji were doing with the imaging was using interpolation to get it to the size that was being claimed. I'm almost sure it was the S7000z which Fuji proudly claimed had a top image size of 4048x3040 but needed 12mp to produce it. If memory serves me correctly, Fuji claim that it is indeed a 12mp sensor but the counter claim is it can only be achieved by electronic wizardry taking the 6.3 effective mp of the sensor up to 12.

    I have a Fuji 6800z and that uses the 2nd (?) generation CCD and claims to generate a 6mp - 2832x2128 - image from the 3.3 mp sensor. Fuji call it "image processing" but the rest of the world would, I'm sure, all it interpolation. Mind you, to my untrained and uneducated eye, the output at that resolution is remarkable.
    Bob Patterson

  10. #10
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    Quote Originally Posted by judge9847
    Rhys, thanks for that but you'll have to forgive me being a bit of a thicko! It comes with age I'm afraid



    I don't understand what you mean by "blowing up" to 6mp: are you referring to the output of what is the final image which is made bigger simply by increasing resolution or are you saying that interpolation is used to get to the 6mp mark? If that's so, then though I might not have been able to explain it quite like that, it's what I thought I was saying.

    John, there was quite a lot of noise from Fuji about one of their more recent cameras when the informed press were suggesting, that despite their claims, all Fuji were doing with the imaging was using interpolation to get it to the size that was being claimed. I'm almost sure it was the S7000z which Fuji proudly claimed had a top image size of 4048x3040 but needed 12mp to produce it. If memory serves me correctly, Fuji claim that it is indeed a 12mp sensor but the counter claim is it can only be achieved by electronic wizardry taking the 6.3 effective mp of the sensor up to 12.

    I have a Fuji 6800z and that uses the 2nd (?) generation CCD and claims to generate a 6mp - 2832x2128 - image from the 3.3 mp sensor. Fuji call it "image processing" but the rest of the world would, I'm sure, all it interpolation. Mind you, to my untrained and uneducated eye, the output at that resolution is remarkable.
    When you look at the 100% crop the 12MP image is only moderately better that 6MP. This is because interpolation takes the base 6MP image and adds pixels in post processing that approximate adjacent pixels. You can do that yourself using any number of software image processors, with better results.

    To get an idea of how rediculous the claim is, compare the image from a Canon EOS 1Ds (11.1MP) to that from a Fuji interpolated 6/12MP image. An unfair comparison you say. Pitting a $700 consumer digicam against a $7500 Pro SLR?

    No more so than Fuji claiming 12MP imaging performance from a 2/3" 6MP CCD. At the very least misleading. A lot of people were mislead thinking the Fuji images were superior to other 3, 4, and 5MP images. When in fact they are not, and in some cases the oposite is true.

    my 5 cents worth (2 cents with many years of inflation, or interpolated if you will).
    Last edited by D70FAN; 08-15-2004 at 07:59 AM.
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