4mp doubled = 16mp!?

Discussion in 'Digital Photography' started by Bolshoy Huy, Mar 21, 2006.

  1. Bolshoy Huy

    Bolshoy Huy Guest

    http://www.image-designer.com/megapixel_mp.html

    "In fact in order to double the resolution of a 4 megapixel camera one
    would
    require a 16 megapixel camera."

    Really? Does this hold true for DSLR or only for P&S?
    Thus I can safely purchase a Canon 10D instead of the 20D
    and save mucho $ without sacrificing picture quality?

    What about CCD vs. CMOS?
    All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.
    Bolshoy Huy, Mar 21, 2006
    #1
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  2. Bolshoy Huy

    Paul J Gans Guest

    Bolshoy Huy <> wrote:
    >http://www.image-designer.com/megapixel_mp.html


    >"In fact in order to double the resolution of a 4 megapixel camera one
    >would
    >require a 16 megapixel camera."


    >Really? Does this hold true for DSLR or only for P&S?
    >Thus I can safely purchase a Canon 10D instead of the 20D
    >and save mucho $ without sacrificing picture quality?


    >What about CCD vs. CMOS?
    >All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.


    Whoa, it is simple geometry.

    Take a piece of scratch paper and draw a square. Now draw
    a line half-way across the width and another half-way across
    the length.

    You had one pixel before. Now you've "doubled" the resolution
    in two directions and, bingo, you have four pixels.

    ---- Paul J. Gans
    Paul J Gans, Mar 21, 2006
    #2
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  3. Bolshoy Huy

    TMG Guest

    Bolshoy Huy wrote:
    > http://www.image-designer.com/megapixel_mp.html
    >
    > "In fact in order to double the resolution of a 4 megapixel camera one
    > would
    > require a 16 megapixel camera."
    >
    > Really? Does this hold true for DSLR or only for P&S?
    > Thus I can safely purchase a Canon 10D instead of the 20D
    > and save mucho $ without sacrificing picture quality?
    >
    > What about CCD vs. CMOS?
    > All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.


    Shouldn't matter about camera type. It has to do with the term "resolution".

    I think it works out to 2^n, where n = the "number of times" resolution
    increases.

    Simple examples:

    You have a 5 X 8 resolution.

    That's 40 whatevers (pixels, widgets, etc.)

    If you double both the horizontal and vertical counts, you get:

    10 X 16

    = 160 whatevers (pixels, widgets, etc.)

    thats 2 times original resolution, but 4 times the original pixels.

    i.e. 2^n, if n is the number of times resolution increases (in this
    case, double, or 2). 2^2=4.

    NOW Triple the original 5 X 8 resolution to:

    15 X 24

    That yields 360 pixels (or widgets).

    That's the original 40 X 2^3.

    See? 2^3 is 2^n, where n = the "times resolution increases" - in this
    case triple, or 3.
    TMG, Mar 21, 2006
    #3
  4. Today Bolshoy Huy commented courteously on the subject at
    hand

    > http://www.image-designer.com/megapixel_mp.html
    >
    > "In fact in order to double the resolution of a 4 megapixel
    > camera one would
    > require a 16 megapixel camera."
    >
    > Really? Does this hold true for DSLR or only for P&S?
    > Thus I can safely purchase a Canon 10D instead of the 20D
    > and save mucho $ without sacrificing picture quality?
    >
    > What about CCD vs. CMOS?
    > All Canon DSLRs use CMOS, but a few sources state it's
    > worse than CCD.
    >

    Pixel resolution is an area measurement - horizontal pixels X
    vertical pixels. So, if you mean horizontal X 2 X vertical X
    2, then yes, 4X pixel dimensions would be 16X mega pixels.

    Where are you in your research? If early on, you should
    realize that mega pixels are but one many important factors in
    defining what is meant by high image quality or "sacrificing
    image quality." The others are sensor size/quality, lens
    quality, camera firmware A-to-D conversion, camera firmware
    image processing, and image storage come immediately to mind.
    For the last, lower price, high MP cameras compress the hell
    outta the JPEGs to get as many large images on a small - read:
    inexpensive - memory card. That alone will destroy any hopes
    of getting a quality image, particularly one to be printed
    much bigger than 4 x 6.

    Megapixels are being "sold" to the mass media as "the more MP
    you have, the better your pictures will be". So, which do you
    think would have better quality, a 6 MP $200 P & S or a 6 MP
    Nikon D50?

    What is really important is what /you/ think is "good"
    quality. That can be measured quantitatively and discussed
    qualitively but not without knowing what subject(s) you shoot,
    lighting conditions, exposure, and fitness of purpose. For
    example, do you intend to only print to small sizes? print to
    large sizes? just view on-screen? all of the above?

    Other things to consider besides price: features, size &
    weight, whether removable lenses are important to you or
    something you don't want, RAW, ergonmics, size of the LCD on
    the back of the camera, photometric options, ability to mount
    an external flash if that is important to you, and so on.

    So, if you provide some clue as to what you want to do and
    what your budget it, you will get much better responses to
    your query.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #4
  5. Bolshoy Huy

    SimonLW Guest

    "Bolshoy Huy" <> wrote in message
    news:...
    > http://www.image-designer.com/megapixel_mp.html
    >
    > "In fact in order to double the resolution of a 4 megapixel camera one
    > would
    > require a 16 megapixel camera."
    >
    > Really? Does this hold true for DSLR or only for P&S?
    > Thus I can safely purchase a Canon 10D instead of the 20D
    > and save mucho $ without sacrificing picture quality?
    >
    > What about CCD vs. CMOS?
    > All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.
    >

    As the others have said holds true given that everything else is the same
    such as the camera's processing and the lens can deal with the extra
    resolution. Doubling resolution makes a huge difference. It is like going
    from 640x480 to 1280x960 on your computer display settings. Doubling the
    megapixel count is enough to make quite a difference. Smaller steps, like
    from 6 to 8 or 8 to 10mp have a very subtle difference.
    -S
    SimonLW, Mar 21, 2006
    #5
  6. Today SimonLW commented courteously on the subject at hand

    > As the others have said holds true given that everything
    > else is the same such as the camera's processing and the
    > lens can deal with the extra resolution. Doubling
    > resolution makes a huge difference. It is like going from
    > 640x480 to 1280x960 on your computer display settings.
    > Doubling the megapixel count is enough to make quite a
    > difference. Smaller steps, like from 6 to 8 or 8 to 10mp
    > have a very subtle difference. -S


    "All others things being equal, but they seldom are" in this
    case also has to do with the maximum amount of image
    information in the original, whether it is a "scene" which is
    the subject of a digital or film camera photo or a scan. Past
    how much is there, it really doesn't matter after a certain
    point how many MP you have.

    To capture all the image information that is really there
    requires spending some money on a "good" camera, with "good"
    lens(es), "good" firmware, "good" image processing, "good"
    sensors, "good" image storage, and other "good" things that
    are beyong most humans to comprehend or measure. Add to that,
    the multiplicity of factors that go into any real photographer
    producing a "good" photograph with any real camera.

    Easy example: I bought my wife a 3 MP Kodak P&S a couple years
    back for $150. It takes "good" pictures, but after about half
    the max MP, it doesn't matter, as the camera compresses the
    hell outta the JPEGs and destroys the quality. I bought the
    upgraded version of the very same Kodak for my daughter 6
    months later. It is 4 MP. But, nothing I can tell was
    "upgraded" except the MP, certainly not the over compression
    issue, so Kodak got another $50 because the buying public -
    me, in this case - had been duped into thinking that another
    MP would equate to better pictures (actually, I couldn't find
    the earlier 3 MP camera so I couldn't buy it). So, I've shown
    my wife and daughter that they're wasting memory space and
    slowing down their image post-processing beyond about 1.5-2
    MP.

    Then, too, both want to print mainly to 4x6, which barely
    requires even one MP.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #6
  7. All Things Mopar <> wrote:
    > "All others things being equal, but they seldom are" in this
    > case also has to do with the maximum amount of image
    > information in the original, whether it is a "scene" which is
    > the subject of a digital or film camera photo or a scan. Past
    > how much is there, it really doesn't matter after a certain
    > point how many MP you have.
    >


    So far we haven't hit that point. The higher megapixel sensors are putting
    out high quality data. Very well suited for cropping or large prints. The
    smaller MP cameras are simply not capable of it. I would really like to print
    20x30 prints without any obvious artifacts, but it is not really possible
    using my 6.1MP Nikon D70. I have had excellent 10x15 prints however. I think
    there is a decent chance that D200 would do what I want, however, I am not
    sure I want to shell out the $$$ for the rarely used feature. I am sure
    eventually I will think of other reasons ;)

    To address your other comment on compression. It is not an issue worth
    discussing with today's DSLR models. You can pick very high resolution JPEG
    or RAW and not have any such issue.

    --
    Thomas T. Veldhouse
    Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1
    Thomas T. Veldhouse, Mar 21, 2006
    #7
  8. Bolshoy Huy

    Derable Guest

    "TMG" <> wrote in message
    news:...
    >
    > Shouldn't matter about camera type. It has to do with the term

    "resolution".
    >
    > I think it works out to 2^n, where n = the "number of times" resolution
    > increases.


    No. It actually increases as n^2.

    >
    > Simple examples:
    >
    > You have a 5 X 8 resolution.
    >
    > That's 40 whatevers (pixels, widgets, etc.)
    >
    > If you double both the horizontal and vertical counts, you get:
    >
    > 10 X 16
    >
    > = 160 whatevers (pixels, widgets, etc.)
    >
    > thats 2 times original resolution, but 4 times the original pixels.
    >
    > i.e. 2^n, if n is the number of times resolution increases (in this
    > case, double, or 2). 2^2=4.


    n^2 = 2^2 = 4 (luckily!)
    >
    > NOW Triple the original 5 X 8 resolution to:
    >
    > 15 X 24
    >
    > That yields 360 pixels (or widgets).
    >
    > That's the original 40 X 2^3.


    Actually it's 40 X 3^2

    >
    > See? 2^3 is 2^n, where n = the "times resolution increases" - in this
    > case triple, or 3.


    n^2 = 3^2 = 9

    9 x 40 = 360. (2^3 is only 8)
    Derable, Mar 21, 2006
    #8
  9. All Things Mopar wrote:
    []
    > Easy example: I bought my wife a 3 MP Kodak P&S a couple years
    > back for $150. It takes "good" pictures, but after about half
    > the max MP, it doesn't matter, as the camera compresses the
    > hell outta the JPEGs and destroys the quality. I bought the
    > upgraded version of the very same Kodak for my daughter 6
    > months later. It is 4 MP. But, nothing I can tell was
    > "upgraded" except the MP, certainly not the over compression
    > issue, so Kodak got another $50 because the buying public -
    > me, in this case - had been duped into thinking that another
    > MP would equate to better pictures (actually, I couldn't find
    > the earlier 3 MP camera so I couldn't buy it). So, I've shown
    > my wife and daughter that they're wasting memory space and
    > slowing down their image post-processing beyond about 1.5-2
    > MP.
    >
    > Then, too, both want to print mainly to 4x6, which barely
    > requires even one MP.


    Kodak had a reputation for producing cameras with a poor JPEG compression
    algorithm. Whether this is still true I don't know, but I do know that
    the Nikon and Panasonic cameras my wife and I have owned have provided a
    number of JPEG "quality" settings, the best of which is visually
    indistinguishable from "RAW" given the correct exposure. There are four
    settings on my 8400, "basic", "standard", "fine" and "extra-fine".

    A4-sized prints from my wife's Nikon 990 (3.2MB) can look stunning. That
    gives a pixel density of just 175 pixels per inch, agreeing with your own
    observations for 4 x 6 inch prints.

    David
    David J Taylor, Mar 21, 2006
    #9
  10. Today Thomas T. Veldhouse commented courteously on the
    subject at hand

    > All Things Mopar <> wrote:
    >> "All others things being equal, but they seldom are" in
    >> this case also has to do with the maximum amount of image
    >> information in the original, whether it is a "scene" which
    >> is the subject of a digital or film camera photo or a
    >> scan. Past how much is there, it really doesn't matter
    >> after a certain point how many MP you have.

    >
    > So far we haven't hit that point. The higher megapixel
    > sensors are putting out high quality data. Very well
    > suited for cropping or large prints. The smaller MP
    > cameras are simply not capable of it.


    This isn't what I'm talking about. A highly detailed, daylight
    image will have more information that goes into a "good" print
    than, say, a night shot which has a generally narrow
    histogram. For the latter, I'd guess that banding would be a
    bigger issue than pixelation.

    > I would really like
    > to print 20x30 prints without any obvious artifacts, but it
    > is not really possible using my 6.1MP Nikon D70.


    What do you mean by "artifacts"? The common use of the term is
    for image damage due to JPEG over compression and has nothing
    to do with inherent image quality put out by your D70.

    > I have
    > had excellent 10x15 prints however. I think there is a
    > decent chance that D200 would do what I want, however, I am
    > not sure I want to shell out the $$$ for the rarely used
    > feature. I am sure eventually I will think of other
    > reasons ;)


    How do you know you can't print that big? I can, and with
    images far, far smaller. Among other things, viewing distance
    is a big factor.

    > To address your other comment on compression. It is not an
    > issue worth discussing with today's DSLR models. You can
    > pick very high resolution JPEG or RAW and not have any such
    > issue.


    You said nothing about what camera you were using. Your OP
    talked mainly about some theoretical stuff so I commented more
    broadly than I would have if you'd said you had a Nikon D70.
    You also didn't say what lens(es) you're using. A "good"
    Nikkor will do much better than some POS 10:1 zoom you bought
    on eBay for $100.

    Many people start off with the notion that they cannot do
    something and, sure enough, they can't. Look at my sig for
    Henry Ford's way of saying that.

    You've also not said what subject(s) you shoot or anything at
    all that would allow people to help you make a judgment. Nor
    have you stated what your definition of "good" is. I have no
    way of knowing what you mean by "excellent" with 10 x 15 yet
    you say you can't print larger. How much larger have you tried
    and what were the results? What were the subject(s), lighting
    conditions, exposure, and overall quality of the images? What
    viewing distances are you attempting, 6" or 6'?

    Let's take a simplified approach to this and assume you have a
    3000 x 2000 image. That isn't quite 6 MP but it makes the math
    easier. Prevailing wisdom says you should have 200 DPI which
    would translate to about what you say you print at - 10 x 15.
    But, as I said above, I have printed to Super B size (13 x 19)
    with images as small as 1280 x 960, which is only about 65
    DPI. But, I put them on an outer wall of the office I used to
    have before I retired and it was difficult for viewers to get
    closer than 4-5 feet, so they looked fine.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #10
  11. Today David J Taylor commented courteously on the subject at
    hand

    >> Easy example: I bought my wife a 3 MP Kodak P&S a couple
    >> years back for $150. It takes "good" pictures, but after
    >> about half the max MP, it doesn't matter, as the camera
    >> compresses the hell outta the JPEGs and destroys the
    >> quality. I bought the upgraded version of the very same
    >> Kodak for my daughter 6 months later. It is 4 MP. But,
    >> nothing I can tell was "upgraded" except the MP, certainly
    >> not the over compression issue, so Kodak got another $50
    >> because the buying public - me, in this case - had been
    >> duped into thinking that another MP would equate to better
    >> pictures (actually, I couldn't find the earlier 3 MP
    >> camera so I couldn't buy it). So, I've shown my wife and
    >> daughter that they're wasting memory space and slowing
    >> down their image post-processing beyond about 1.5-2 MP.
    >>
    >> Then, too, both want to print mainly to 4x6, which barely
    >> requires even one MP.

    >
    > Kodak had a reputation for producing cameras with a poor
    > JPEG compression algorithm. Whether this is still true I
    > don't know, but I do know that the Nikon and Panasonic
    > cameras my wife and I have owned have provided a number of
    > JPEG "quality" settings, the best of which is visually
    > indistinguishable from "RAW" given the correct exposure.
    > There are four settings on my 8400, "basic", "standard",
    > "fine" and "extra-fine".


    That wasn't my point, David. I was simply saying that a paste
    plastic lens, crappy firmware, and over-compression on my wife
    and daughter's Kodaks preclude a "good" print no matter what
    MP - i.e., PPI - you try. At the time I made my comments, I
    don't recall the OP saying they had a Nikon D70 - or I missed
    it. I also don't recall seeing what lens(es) they're using nor
    anything at all about the images themselves.

    > A4-sized prints from my wife's Nikon 990 (3.2MB) can look
    > stunning. That gives a pixel density of just 175 pixels
    > per inch, agreeing with your own observations for 4 x 6
    > inch prints.
    >

    I just replied to the OP that I've gotten Super B 13 x 19
    prints off a crappy HP 1220C wide-carriage ink jet with only
    65 PPI (I think I said DPI previously, which is the wrong
    term). And, as I opined to the OP, viewing distance is
    everything if you're going to drop below 300 PPI and certainly
    into the 150-200 PPI range. At the 30 x 20 size I think the OP
    is asking about, a 300 PPI image would require 9000 x 6000
    pixels = 51 MP. Don't think there's any cameras around that
    can do that, so some sort of compromise on "good" needs to be
    defined and accepted.

    This basic "how many MP do I need for a good print" debate
    goes on and on and on and on and on here, in the PSP forums,
    everyplace. People want to shave $$$ off what they buy and
    delude themselves into thinking they can get "good" results.
    Or, they jump to conclusions based on incorrect or unfounded
    assumptions about all the factors that go into a "good" image
    without defining the criteria for making a judgment whether a
    image will produce crap, good, or superb prints.

    One, more item: No one has talked about the technology to
    actually create the prints. Dot matrix? Ink jet? Color laser?
    Dye sublimation? Custom lab with color calibration that costs
    upwards of $250/print? I just looked last week at two Epson
    wide-carriage printers that print up to 11" x 50" banners (or
    tabloid 11 x 17). One was $300 and the other $500 or $600. I
    doubt that a $300 or a $500 6-cartridge ink jet is capable of
    printing the full capabilities of 6, 8, 12, or 16 MP, although
    I've seen the results and they are quite good.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #11
  12. Bolshoy Huy

    ASAAR Guest

    On Tue, 21 Mar 2006 05:00:34 +0000 (UTC), Paul J Gans wrote:

    >> What about CCD vs. CMOS?
    >> All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.

    >
    > Whoa, it is simple geometry.


    Whoa, the Bolshoy troll struck again! <g>
    ASAAR, Mar 21, 2006
    #12
  13. All Things Mopar <> wrote:
    >
    > This isn't what I'm talking about. A highly detailed, daylight
    > image will have more information that goes into a "good" print
    > than, say, a night shot which has a generally narrow
    > histogram. For the latter, I'd guess that banding would be a
    > bigger issue than pixelation.
    >


    I know what you were talking about. You were saying that the camera you used
    had such horrible jpeg compression issues that a higher MP sensor would not
    benefit the final image. We have the Kodak Easyshare (3.1 or 3.2MP) and know
    people who have the 2MP and 4PM versions. The highest quality JPEG settings
    did indeed make more detailed images with the higher MP. I really don't know
    why you think otherwise. Either way, the image resolution was indeed higher
    with the higher MP, reguardless of what the image processing did to it after
    the exposure was captured. JPEG issues like that are NOT anything common to
    be sure and not worthy of consideration with the average purchase decision.


    > What do you mean by "artifacts"? The common use of the term is
    > for image damage due to JPEG over compression and has nothing
    > to do with inherent image quality put out by your D70.
    >


    I meant pixellation.

    The rest of your message seemed directed at the D70. I was indicating that I
    own a D70, and not the OP.
    --
    Thomas T. Veldhouse
    Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1
    Thomas T. Veldhouse, Mar 21, 2006
    #13
  14. All Things Mopar wrote:
    []
    > This basic "how many MP do I need for a good print" debate
    > goes on and on and on and on and on here, in the PSP forums,
    > everyplace. People want to shave $$$ off what they buy and
    > delude themselves into thinking they can get "good" results.
    > Or, they jump to conclusions based on incorrect or unfounded
    > assumptions about all the factors that go into a "good" image
    > without defining the criteria for making a judgment whether a
    > image will produce crap, good, or superb prints.


    Yes, I would agree with that. What I wanted to point out is that there
    are better non-SLR cameras than Kodak's earlier efforts, and you don't
    necessarily need to go the DSLR route for good quality pictures.

    (I would also agree that "megapixels" are now bandied round like "watts"
    were in the hi-fi era. Remember "peak instantaneous but not all the time,
    not at all frequencies, not on both channels, and perhaps not on a
    Tuesday" watts?)

    David
    David J Taylor, Mar 21, 2006
    #14
  15. Bolshoy Huy

    Paul J Gans Guest

    David J Taylor <-this-bit.nor-this-part.uk> wrote:
    >All Things Mopar wrote:
    >[]
    >> Easy example: I bought my wife a 3 MP Kodak P&S a couple years
    >> back for $150. It takes "good" pictures, but after about half
    >> the max MP, it doesn't matter, as the camera compresses the
    >> hell outta the JPEGs and destroys the quality. I bought the
    >> upgraded version of the very same Kodak for my daughter 6
    >> months later. It is 4 MP. But, nothing I can tell was
    >> "upgraded" except the MP, certainly not the over compression
    >> issue, so Kodak got another $50 because the buying public -
    >> me, in this case - had been duped into thinking that another
    >> MP would equate to better pictures (actually, I couldn't find
    >> the earlier 3 MP camera so I couldn't buy it). So, I've shown
    >> my wife and daughter that they're wasting memory space and
    >> slowing down their image post-processing beyond about 1.5-2
    >> MP.
    >>
    >> Then, too, both want to print mainly to 4x6, which barely
    >> requires even one MP.


    >Kodak had a reputation for producing cameras with a poor JPEG compression
    >algorithm. Whether this is still true I don't know, but I do know that
    >the Nikon and Panasonic cameras my wife and I have owned have provided a
    >number of JPEG "quality" settings, the best of which is visually
    >indistinguishable from "RAW" given the correct exposure. There are four
    >settings on my 8400, "basic", "standard", "fine" and "extra-fine".


    >A4-sized prints from my wife's Nikon 990 (3.2MB) can look stunning. That
    >gives a pixel density of just 175 pixels per inch, agreeing with your own
    >observations for 4 x 6 inch prints.


    I agree with David. I generally shoot (Canon 300D) at the
    least loss JPG setting. It is hard to see artifacts.

    ----- Paul J. Gans
    Paul J Gans, Mar 21, 2006
    #15
  16. Today Thomas T. Veldhouse commented courteously on the
    subject at hand

    > All Things Mopar <> wrote:
    >>
    >> This isn't what I'm talking about. A highly detailed,
    >> daylight image will have more information that goes into a
    >> "good" print than, say, a night shot which has a generally
    >> narrow histogram. For the latter, I'd guess that banding
    >> would be a bigger issue than pixelation.

    >
    > I know what you were talking about. You were saying that
    > the camera you used had such horrible jpeg compression
    > issues that a higher MP sensor would not benefit the final
    > image. We have the Kodak Easyshare (3.1 or 3.2MP) and know
    > people who have the 2MP and 4PM versions. The highest
    > quality JPEG settings did indeed make more detailed images
    > with the higher MP.


    Little Kodaks use terms like "good", "better", and "best" to
    me 1 MP, 2 MP, 3 MP, but generally /not/ what "good" cameras
    refer to for JPEG such as "basic", "normal", and "fine". So,
    my 2 Kodaks have no ability whatsoever to alter compression,
    just mega pixels. But, my Rebel XT gives me 3 resolutions (2,
    4, 8 MP) and "normal" and "fine" compression.

    I really don't know why you think
    > otherwise.


    I think otherwise because JPEG has no-thing to do with fine
    detail and sharpness except that it can destroy it. But, I
    assume you are already shooting with the lowest compression
    possible in your camera and using low compression when you
    save from your fav graphics editor.

    Either way, the image resolution was indeed
    > higher with the higher MP, reguardless of what the image
    > processing did to it after the exposure was captured. JPEG
    > issues like that are NOT anything common to be sure and not
    > worthy of consideration with the average purchase decision.
    >

    You're still mixing these two issues up. One is an example of
    little Kodak P&S's that over compress and the other is the
    need for image "information" that /you/ seem to require to do
    large prints from as large an image in mega pixels as you can
    afford. For the latter, I was saying that a night scene is
    "simpler" than a highly detailed daylight shot, say of a car
    or architecture or still life.

    Lower JPEG compression doesn't "create" detail, it simply
    doesn't destroy what is already there by using its lossy
    algoritithm to throw out pixels. As I said earlier, the main
    issue with JPEG is the "mushing" of fine detail through the
    creation of JPEG artifacts, which most people define as
    streaks, blobs, spots, and other easily visible areas of large
    expanses of color or in areas of fine detail.

    JPEG compression /is/ a very important purchasing decision
    criterion. If it ain't got it, you ain't gonna get decent
    images. Period. That's not an issue with a Rebel or D70 but is
    for cheap, high MP P&S.

    >> What do you mean by "artifacts"? The common use of the
    >> term is for image damage due to JPEG over compression and
    >> has nothing to do with inherent image quality put out by
    >> your D70.

    >
    > I meant pixellation.


    That isn't what "artifact" means. See above. Pixelation occurs
    from trying to force a small number of pixels into a large
    area linearly, such as using too small an image to print -
    which is /your/ point.

    So, if your definition of image degradation visible in a print
    is pixelation, then, yes, more mega pixels /should/ yield less
    damage. I say "should" because all those other pesky factors
    such as lens, image processing, lighting, your skill as a
    photographer, and what you do post-processing the image are
    just as important, if not more so, than a simple increase in
    mega pixels. Again, "all other things being equal, but they
    seldom are."

    Back to printing, most/all printer drivers do simple pixel
    resizes to "create" pixels to cover tha paper size a graphics
    app and user specify, no matter what the claimed DPIs at
    various quality levels in printers you have to choose from. If
    the information isn't in the pixels sent to the printer, it
    will print /something/, which /may/ result in pixelation. It
    can also result in other problems, such as banding.

    > The rest of your message seemed directed at the D70. I was
    > indicating that I own a D70, and not the OP.


    I didn't accurately track who said what, so I apologize. The
    comments are flying in this thread with several misconceptions
    along the way.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #16
  17. Today David J Taylor commented courteously on the subject at
    hand

    > All Things Mopar wrote:
    > []
    >> This basic "how many MP do I need for a good print" debate
    >> goes on and on and on and on and on here, in the PSP
    >> forums, everyplace. People want to shave $$$ off what they
    >> buy and delude themselves into thinking they can get
    >> "good" results. Or, they jump to conclusions based on
    >> incorrect or unfounded assumptions about all the factors
    >> that go into a "good" image without defining the criteria
    >> for making a judgment whether a image will produce crap,
    >> good, or superb prints.

    >
    > Yes, I would agree with that. What I wanted to point out
    > is that there are better non-SLR cameras than Kodak's
    > earlier efforts, and you don't necessarily need to go the
    > DSLR route for good quality pictures.


    David, I wasn't even talking about Kodak DSLRs. I just used
    the simplest example I could think of from personal experience
    to illustrate why more MP doesn't necessarily yield better
    prints. You and I are really saying the same thing, I think.
    You're saying the light is on when the switch is up and I'm
    saying the light is off when the switch is down. We both know
    how light switches work, right? <grin>

    > (I would also agree that "megapixels" are now bandied round
    > like "watts" were in the hi-fi era. Remember "peak
    > instantaneous but not all the time, not at all frequencies,
    > not on both channels, and perhaps not on a Tuesday" watts?)
    >

    I'm seeing 6 MP P&S cameras that are down in the POS range of
    $100-50. I have friends that ask me what I shoot at. I say "2
    or 4 MP" and they say "then, you either don't know what you're
    doing or don't care what your images look like." Well, I /do/
    know what I'm doing and I /do/ care what my images look like.
    I also understand fitness of purpose and I understand PPI
    necessary for "good" prints as we agreed on earlier. But,
    since my friends don't - and I want to keep them as friends -
    I just say "OK" and change the subject.

    And, for your metaphor to watts, HD and external HD
    manufacturers like to talk about theoretical transfer rates,
    sustained transfer rates, burst transfer rates, Windoze
    transfer rates, and several other kinds. But, they seldom
    publish other than the largest number they can contrive in the
    lab, which is usually done by connecting their drive to some
    huge data pipe and blasting 100 mega ton nuclear blasts to the
    read/write heads. And, they claim rates which are an order of
    magnitude higher than one can get with Windoze. So what? These
    are just comparo specs, as both of us know. One has to
    understand what all this techo babbel means to sort out what
    is important from what isn't and what is real and attainable
    and what is lab bullshit.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry
    Ford
    All Things Mopar, Mar 21, 2006
    #17
  18. Today Paul J Gans commented courteously on the subject at
    hand

    > I agree with David. I generally shoot (Canon 300D) at the
    > least loss JPG setting. It is hard to see artifacts.


    Paul, I experimented with both my earlier EVF cameras and could
    easily see artifacts (the real kind, not the pixelation kind) at
    so-called "normal" compression, so I immediately went to "fine".
    I've never even tried the lower quality/higher compression on my
    Rebel XT. What's the point of spending $900 on a body and $1,250
    on a lens and destroy the image when memory is so cheap these
    days?

    /Occasionally/ I will see artifacts even at "fine", but it is
    quite rare, and they are easy to get rid of as I resize down to
    finished size and do the rest of my post-processing.

    --
    ATM, aka Jerry

    "Whether You Think You CAN Or CAN'T, You're Right." – Henry Ford
    All Things Mopar, Mar 21, 2006
    #18
  19. Bolshoy Huy

    Roy G Guest

    "Bolshoy Huy" <> wrote in message
    news:...
    > http://www.image-designer.com/megapixel_mp.html
    >
    > "In fact in order to double the resolution of a 4 megapixel camera one
    > would
    > require a 16 megapixel camera."
    >
    > Really? Does this hold true for DSLR or only for P&S?
    > Thus I can safely purchase a Canon 10D instead of the 20D
    > and save mucho $ without sacrificing picture quality?
    >
    > What about CCD vs. CMOS?
    > All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.
    >


    Hi all.

    Very interesting thread which seems to have wandered off the original
    subject just a little.

    I think the important part is not that doubling the pixel count in each
    dimention causes the Mp figure to increase 4 times.

    The inportance is that Doubling the Mp count does not have have nearly as
    dramatic an effect as the Marketing people would like us all to believe.

    A 6Mp Camera has 3000 x 2000 pixels, (rounded for my ease). Increasing to
    12 Mp, gives us (roughly) 4250 x 2830 Pixels.

    Certainly the increase is worthwhile, on the long side, from 3000 to 4250,
    but it is nothing like we would expect from the Marketing Hype we would get
    about that "Doubling".

    It does demonstrate that increasing from 6Mp to 8Mp is even less dramatic
    than quite a lot of the Posters were shouting about, when the Rebels went to
    8Mp and the Nikons stayed at 6Mp. Roughly an extra 400 pixel on the long
    side, or in Print terms at 240 PPI from a 12.5 inch to a 14 inch Print.

    I think this is something we should all keep in mind when the next
    generation of Cameras, with even more Mps, come out, and the Hype starts.

    Roy G
    Roy G, Mar 22, 2006
    #19
  20. Bolshoy Huy

    Roy G Guest

    "Bolshoy Huy" <> wrote in message
    news:...
    > http://www.image-designer.com/megapixel_mp.html
    >
    > "In fact in order to double the resolution of a 4 megapixel camera one
    > would
    > require a 16 megapixel camera."
    >
    > Really? Does this hold true for DSLR or only for P&S?
    > Thus I can safely purchase a Canon 10D instead of the 20D
    > and save mucho $ without sacrificing picture quality?
    >
    > What about CCD vs. CMOS?
    > All Canon DSLRs use CMOS, but a few sources state it's worse than CCD.
    >


    Hi all.

    Very interesting thread which seems to have wandered off the original
    subject just a little.

    I think the important part is not that doubling the pixel count in each
    dimention causes the Mp figure to increase 4 times.

    The inportance is that Doubling the Mp count does not have have nearly as
    dramatic an effect as the Marketing people would like us all to believe.

    A 6Mp Camera has 3000 x 2000 pixels, (rounded for my ease). Increasing to
    12 Mp, gives us (roughly) 4250 x 2830 Pixels.

    Certainly the increase is worthwhile, on the long side, from 3000 to 4250,
    but it is nothing like we would expect from the Marketing Hype we would get
    about that "Doubling".

    It does demonstrate that increasing from 6Mp to 8Mp is even less dramatic
    than quite a lot of the Posters were shouting about, when the Rebels went to
    8Mp and the Nikons stayed at 6Mp. Roughly an extra 400 pixel on the long
    side, or in Print terms at 240 PPI from a 12.5 inch to a 14 inch Print.

    I think this is something we should all keep in mind when the next
    generation of Cameras, with even more Mps, come out, and the Hype starts.

    Roy G
    Roy G, Mar 22, 2006
    #20
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