Need help in calculating digital camera's MP

On Fri, 2 Jan 2009 12:45:07 -0800 (PST), wrote in
:

Thanks for all of the info and discussions. However, I just simply
could not get sharp, crisp photos from my cameras.
I tried some photos using a 3MP Lumix digital camera and they show
excellent colour and sharpness under my 21 in. LCD computer screen.
They are close-ups of a red flower, and showing its extremely focused
and sharp filaments. I used the flower (no flash and under bright
light) as it usually gives the best resolution and colour. I also shot
a couple of photos using a Canon G7 (10 MP). The results have also
been disappointing in my TV. These JPG files are all over 2MP that all
of you indicated. So, what's wrong? I just copied the JPG files into
a CD and use a DVD player attached to the TV. They just do not show
sharp photos that I always see at the TV stores when they display the
TVs. Are they using high MP photos?

Your problem (limiting factor) is the DVD player, which isn't capable of
high definition, and probably does a poor job of photo resizing like
most DVD players. For best results from your DVD player, feed it photos
at native 640x480 resolution. Anything more than that is wasted, and
probably results in slow and poor resizing. For better results you need
Blu-ray.

--
Very best wishes for the holiday season and for the coming new year,
John

On Fri, 02 Jan 2009 12:45:07 -0800, aniramca wrote:

On Jan 2, 2:04Â*pm, "David J Taylor" -
this-part.nor-this-bit.co.uk wrote:
John Navas wrote:

[]



Most current TV electronics aren't capable of that kind of pixel
level resolution -- put the HD input on pause and look closely -- and
your eyes couldn't see it in a moving image even if.

I don't know if any tests have been done to check what the actual
ratio is, but I recall that the Foveon sensor is reckoned by some to
be equivalent to something like twice the number of pixels.

That's not directly comparable.

I therefore revise my estimate to, for a 4:3 aspect ratio camera 2 *
1920 * 1440, i.e. about 5-6Mpix, resampled and cropped to a 16:9
1920 x 1080 ready-to-display image.

Cropping a movie is usually impractical. 2-3 MP is really enough.

The LCD TVs I've seen are quite capable of pixel-level resolution,
John. Recall that the OP wants stills, not movies.

David

Thanks for all of the info and discussions. However, I just simply could
not get sharp, crisp photos from my cameras. I tried some photos using a
3MP Lumix digital camera and they show excellent colour and sharpness
under my 21 in. LCD computer screen. They are close-ups of a red flower,
and showing its extremely focused and sharp filaments. I used the flower
(no flash and under bright light) as it usually gives the best
resolution and colour. I also shot a couple of photos using a Canon G7
(10 MP). The results have also been disappointing in my TV. These JPG
files are all over 2MP that all of you indicated. So, what's wrong? I
just copied the JPG files into a CD and use a DVD player attached to the
TV. They just do not show sharp photos that I always see at the TV
stores when they display the TVs. Are they using high MP photos?

Thanks any way for the information. It appears that every one agrees
that you only need a 2MP JPG file to produce excellent photos in a 46
in. TV screen. I am just not happy for what I got so far and perhaps I
will keep trying. Perhaps I should try to download one of the best and
sharp , over 2MB photos from the internet and try that on my TV. Does
the process to download to the TV matter? or it does not matter as long
as they are a JPG files?

It sounds to me like you are basically displaying in TV mode - probably
analog TV mode - which is simply not high resolution. Suggest you use a
high def or computer monitor interface. You may not be able to do any
better.

ray wrote:
On Fri, 02 Jan 2009 12:45:07 -0800, aniramca wrote:

On Jan 2, 2:04 pm, "David J Taylor"
-
this-part.nor-this-bit.co.uk wrote:
John Navas wrote:

[]



Most current TV electronics aren't capable of that kind of pixel
level resolution -- put the HD input on pause and look closely --
and your eyes couldn't see it in a moving image even if.

I don't know if any tests have been done to check what the
actual
ratio is, but I recall that the Foveon sensor is reckoned by
some
to be equivalent to something like twice the number of pixels.

That's not directly comparable.

I therefore revise my estimate to, for a 4:3 aspect ratio camera
2 * 1920 * 1440, i.e. about 5-6Mpix, resampled and cropped to a
16:9 1920 x 1080 ready-to-display image.

Cropping a movie is usually impractical. 2-3 MP is really enough.

The LCD TVs I've seen are quite capable of pixel-level resolution,
John. Recall that the OP wants stills, not movies.

David

Thanks for all of the info and discussions. However, I just simply
could not get sharp, crisp photos from my cameras. I tried some
photos using a 3MP Lumix digital camera and they show excellent
colour and sharpness under my 21 in. LCD computer screen. They are
close-ups of a red flower, and showing its extremely focused and
sharp filaments. I used the flower (no flash and under bright
light)
as it usually gives the best resolution and colour. I also shot a
couple of photos using a Canon G7 (10 MP). The results have also
been disappointing in my TV. These JPG files are all over 2MP that
all of you indicated. So, what's wrong? I just copied the JPG
files
into a CD and use a DVD player attached to the TV. They just do not
show sharp photos that I always see at the TV stores when they
display the TVs. Are they using high MP photos?

Thanks any way for the information. It appears that every one
agrees
that you only need a 2MP JPG file to produce excellent photos in a
46
in. TV screen. I am just not happy for what I got so far and
perhaps
I will keep trying. Perhaps I should try to download one of the
best
and sharp , over 2MB photos from the internet and try that on my
TV.
Does the process to download to the TV matter? or it does not
matter
as long as they are a JPG files?

It sounds to me like you are basically displaying in TV mode -
probably analog TV mode - which is simply not high resolution.
Suggest you use a high def or computer monitor interface. You may
not
be able to do any better.

The key here is "I just copied the JPG files into a CD and use a DVD
player attached to the TV."

If that is not a Blu-Ray DVD player attached via HDCP then it is
likely not capable of sending more than standard analog broadcast
resolution to the TV.

With regard to "They just do not show sharp photos that I always see
at the TV stores when they display the TVs. Are they using high MP
photos? ", they'll either be using a DVI/HDMI input from a PC or an
HDCP input from a blu-ray player or HDTivo or the like.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On Fri, 2 Jan 2009 16:41:40 -0500, "J. Clarke"
wrote in :

The key here is "I just copied the JPG files into a CD and use a DVD
player attached to the TV."

If that is not a Blu-Ray DVD player attached via HDCP then it is
likely not capable of sending more than standard analog broadcast
resolution to the TV.

DVD resolution is quite a bit higher than analog broadcast resolution --
many DVD players have progressive scan component output, quite a few
with scan doubling, and some are capable of upscaling to HD resolution.

--
Very best wishes for the holiday season and for the coming new year,
John

On Fri, 2 Jan 2009 14:32:28 -0800 (PST), wrote in
:

Thanks for the info. Now I see that a JPG with enough MP does not
necessarily guarantee to produce a good picture in a TV. How does this
different from viewing in a computer using, say 24 in. LCD monitor?

A typical computer monitor has much higher resolution than a DVD player.

I wonder if one of those TV from Sony or Panasonic, which you can plug
in the memory card directly into the TV can produce the high quality
pictures directly.

Some do, but not all.

So, I just cannot simply dump the JPG files in a CD
and play it. I knew that there seems always be a catch somewhere.

You can do it, but there is a catch.

--
Very best wishes for the holiday season and for the coming new year,
John

David J Taylor added these comments in the current discussion du
jour ...

.. although a "normal" 4:3 aspect ratio camera needs to be 1920
x 1440 pixels to at least match the display resolution
horizontally (i.e. 2.76 Mpix), and it would be helpful to have
some crop margin for those times when your framing isn't perfect
, so say 5-6Mpix.

Leaving the question, are any current cameras less than 5-6Mpix?

David, we've had this discussion ad nauseum, namely is "more mega
pixels better images" or not. You are obviously correct that few
cameras other than toys are less than about 6 MP but that hardly
means they are all created equal.

--
Jerry, aka HP

"If you are out of work and hungry, eat an environmentalist" -
Florida billboard

David J Taylor added these comments in the current discussion du
jour ...

There's another reason for using more pixels. In the display,
each of the pixels is an RGB triple, i.e. a full colour pixel,
whereas in the camera each pixel is either red, green or blue.
So to match the display resolution, you may need more pixels in
the (Bayer) camera than are on the display. I don't know if any
tests have been done to check what the actual ratio is, but I
recall that the Foveon sensor is reckoned by some to be
equivalent to something like twice the number of pixels.

Huh?! How does the way a camera "sees" a pixel translate into how a
TV sees one? Or, a PC monitor? 16 million color requires 3 bytes per
pixel, of course, but how does this matter to a TV? Isn't it far more
important how the TV system that reads digital images from, say, it's
memory card slot, depend on how well it fills the screen from
whatever it is provided?

I therefore revise my estimate to, for a 4:3 aspect ratio camera
2 * 1920 * 1440, i.e. about 5-6Mpix, resampled and cropped to a
16:9 1920 x 1080 ready-to-display image.

True enough but my Canon DSLR creates 3:2 images. But, whether a
camera is 4:3 or 3:2 or something else, to get all the way to a
16:9/16:10 aspect ratio also requires the photographer to be VERY
aware of how they must crop their images or something important will
likely be lost.

--
Jerry, aka HP

"If you are out of work and hungry, eat an environmentalist" -
Florida billboard

John Navas wrote:
On Fri, 02 Jan 2009 20:04:19 GMT, "David J Taylor"
[]
The LCD TVs I've seen are quite capable of pixel-level resolution,
John.

Brand and model please.

All I have tested, when fed from the computer input.

Examples:
Logik L19LID648
Samsung LE26R74BD

David

wrote:
[]
Thanks for all of the info and discussions. However, I just simply
could not get sharp, crisp photos from my cameras.
I tried some photos using a 3MP Lumix digital camera and they show
excellent colour and sharpness under my 21 in. LCD computer screen.
They are close-ups of a red flower, and showing its extremely focused
and sharp filaments. I used the flower (no flash and under bright
light) as it usually gives the best resolution and colour. I also shot
a couple of photos using a Canon G7 (10 MP). The results have also
been disappointing in my TV. These JPG files are all over 2MP that all
of you indicated. So, what's wrong? I just copied the JPG files into
a CD and use a DVD player attached to the TV. They just do not show
sharp photos that I always see at the TV stores when they display the
TVs. Are they using high MP photos?

Thanks any way for the information. It appears that every one agrees
that you only need a 2MP JPG file to produce excellent photos in a 46
in. TV screen. I am just not happy for what I got so far and perhaps I
will keep trying. Perhaps I should try to download one of the best and
sharp , over 2MB photos from the internet and try that on my TV. Does
the process to download to the TV matter? or it does not matter as
long as they are a JPG files?

The process of getting the image onto the TV absolutely /does/ matter!
For best results, I would currently recommend using the computer (VGA)
input to the TV, and driving it at its native resolution (on two of my TVs
this means driving at 1366 x 768 pixels, and 1440 x 900 pixels). Switch
the TV on before connecting the computer, and then the display card in the
computer will recognise the TV's resolution. You would need to check how
the TV handles JPEGs on a DVD. If going through a DVD player, for
example, it might just rescale the images to 640 x 480 pixels! See if the
TV has a memory card slot. That /might/ be better.

Cheers,
David

nospam wrote:
In article , David J
Taylor
wrote:

There's another reason for using more pixels. In the display, each
of the pixels is an RGB triple, i.e. a full colour pixel, whereas in
the camera each pixel is either red, green or blue. So to match the
display resolution, you may need more pixels in the (Bayer) camera
than are on the display. I don't know if any tests have been done
to check what the actual ratio is, but I recall that the Foveon
sensor is reckoned by some to be equivalent to something like twice
the number of pixels.

the foveon fans come up with their own math to justify the sensor's
existence. it's often hilarious. i've seen everything from 1.4x to
over 3x, with some even claiming infinite resolution, depending on how
creative the (misinformed) zealot is. the main difference is not the
co-located layers, but rather the false detail from the lack of an
anti-alias filter and heavy sharpening in the raw processing.

Yes, it was the only closely related comparison I could think of at the
time, and has unfortunate connotations for the photographic community!
Perhaps the 3-CCD video camera would have been a better comparison, but
there you have alignment issues between R, G & B which are not issues for
a LCD screen. I'll accept a factor of two until I see a more reasoned
(and perhaps empirically-tested) value.

David