Microsoft ClearType and HDTV standards interpolation

Yesterday night I installed Internet Explorer 7 and when I ran it it went to
a setup screen which had ClearType set as default so I wondered why that was
when I was using a CRT monitor and I thought ClearType was only supposed to
work on LCD screens using a digital link or laptops. Anyway I went along
with it and fine-tuned it to work on my monitor, since Microsoft said it
could imporove the rendering of fonts on CRT monitors as well, and it
worked, probably because I am using a Trinitron based monitor which displays
the pixels in columns like a LCD screen. After that I took a screen capture
of the newly rendered fonts and saw that when magnified that all the font
edges were tinted either red or blue but when shown at normal size I could
hardly notice that at the resolution I was using which is 1920x1440.

Since ClearType works by using all the individual sub pixels in the RGB
group its is obvious it will only work properly at a monitors maximum native
resolution. Fortunately with my monitor this corresponded to the resolution
I was using but if I had been using 960x720 which is comparable to the
resolution of 720p HDTV I would have seen all the edges of the letters
tinted red or blue like when I magnified the screen capture.

Now this brings me to High Definition TV in general, and I have concluded
that 720p cannot be interpolated properly when being displayed on a 1080i
LCD HDTV screen without causing serious picture degradation if it was
originally shot on a 720p video camera because such a camera must work in
the same way as Microsoft ClearType. When the image is projected by the
camera lens on the CCD the individual Red, Green and Blue subpixels on the
CCD will see the picture just like Clear Type. So if the edge of a letter
crosses between one RGB group and an other RGB group the pixels making up
the image of the letter "l" may look like "RGbrGB" where lower case
indicates the pixel is dimmed and capitals indicate it is brightly lit, and
this is how ClearType renders the letter "I".

This means that 720p pictures cannot be interpolated to fit on a 1920x1080
monitor without causing red and blue fringes to appear visible on any
vertical edges or on text or areas of high contrast unless intelligent
interpolation and boundary recognition software is use. Even worse is that
unless the LCD monitor you are using is exactly 960 pixels wide then even
the native 720p picture won't be displayed properly. Worse still is that
fact that almost all LCD screens I have seen use a grid which is 1024x768
pixels so they will in fact seriously degrade a native 720p picture. Of
course on top of this the problem of sub sampling the colour at half the
resolution of the luminance will cause even more image degradation so HDTV
ends up giving you a picture which is complete garbage. No wonder I've never
been able to display a 576 line PAL picture on my monitor interpolated to
fit my normal display resolution of 1920x1440 which for a 16:9 picture
provides a letterbox the same dimensions as a 1920x1080 HDTV.

When are we going to get proper high definition TV and by that I mean no
sub-sampling of the colour, only 1080i/p pictures transmitted and only LCD
TVs that use a 1920x1080 grid being used to display the picture?

Agamemnon wrote:

[snip]

Now this brings me to High Definition TV in general, and I have
concluded that 720p cannot be interpolated properly when being
displayed on a 1080i LCD HDTV screen without causing serious picture
degradation if it was originally shot on a 720p video camera because
such a camera must work in the same way as Microsoft ClearType. When
the image is projected by the camera lens on the CCD the individual
Red, Green and Blue subpixels on the CCD will see the picture just
like Clear Type.

Assuming the image sensor consists of a single CCD with each pixel
spatially divided into r g & b subpixels. I've no idea if that's how
professional video equipment is designed.

So if the edge of a letter crosses between one RGB group and an other
RGB group the pixels making up the image of the letter "l" may look
like "RGbrGB" where lower case indicates the pixel is dimmed and
capitals indicate it is brightly lit, and this is how ClearType
renders the letter "I".

You're also assuming the image projected onto the CCD will all be in pin
sharp focus across the entire ccd. Again, I don't know if that's true,
but I doubt it's a safe assumption.

Further, you assume that visual elements on the scale of these subpixels
will be common in the images /&/ that the video encoding process will
preserve that level of detail (*)

This means that 720p pictures cannot be interpolated

If it were true, it would mean the 720p pictures were not a very good
approximation to the original images (& additionally, as you say, would
render badly on any display other than one offering a one to one sub
pixel correspondence to the original ccd - in fact if (*) isn't true,
they'll render badly on those devices too).

If actual cameras operate in this way they strike me as being terribly
designed. I'd be surprised if this were true.

If it isn't true, interpolation presents none of the problems you
describe, though of course there are others.

[snip]

--
Michael
m r o z a t u k g a t e w a y d o t n e t

"Michael Rozdoba" wrote in message
...
Agamemnon wrote:

[snip]

Now this brings me to High Definition TV in general, and I have concluded
that 720p cannot be interpolated properly when being displayed on a 1080i
LCD HDTV screen without causing serious picture degradation if it was
originally shot on a 720p video camera because such a camera must work in
the same way as Microsoft ClearType. When the image is projected by the
camera lens on the CCD the individual Red, Green and Blue subpixels on
the CCD will see the picture just like Clear Type.

Assuming the image sensor consists of a single CCD with each pixel
spatially divided into r g & b subpixels. I've no idea if that's how
professional video equipment is designed.

So if the edge of a letter crosses between one RGB group and an other
RGB group the pixels making up the image of the letter "l" may look like
"RGbrGB" where lower case indicates the pixel is dimmed and capitals
indicate it is brightly lit, and this is how ClearType renders the letter
"I".

You're also assuming the image projected onto the CCD will all be in pin
sharp focus across the entire ccd. Again, I don't know if that's true,
but I doubt it's a safe assumption.

Further, you assume that visual elements on the scale of these subpixels
will be common in the images /&/ that the video encoding process will
preserve that level of detail (*)

This means that 720p pictures cannot be interpolated

If it were true, it would mean the 720p pictures were not a very good
approximation to the original images (& additionally, as you say, would
render badly on any display other than one offering a one to one sub
pixel correspondence to the original ccd - in fact if (*) isn't true,
they'll render badly on those devices too).

If actual cameras operate in this way they strike me as being terribly
designed. I'd be surprised if this were true.

If it isn't true, interpolation presents none of the problems you
describe, though of course there are others.

If it isn't true then high definition TV isn't really high definition and
you might as well interpolate a 576 line PAL picture.


[snip]

--
Michael
m r o z a t u k g a t e w a y d o t n e t

Agamemnon wrote:

[...] because such a camera must work in
the same way as Microsoft ClearType. When the image is projected by the
camera lens on the CCD the individual Red, Green and Blue subpixels on the
CCD will see the picture just like Clear Type.

Digital image capture devices do not have to work like ClearType at all.

As you correctly stated, many digital cameras, still or moving, use
individual RGB pixels - usually in groups of 4, often with an extra green
pixel or in some cases another colour like Cyan. These do capture, in raw
format, in the manner you describe. However inside the camera, a demosaic
algorithm converts the raw data from the 2x2 groups of RGB[G] pixels into
individual pixels of a full colour image. In the case of digital video
capture devices, this happens in real time, per frame. Yes, this means
that if I have, say, a 3200x2400 image from an ~8MP conventional digital
stills camera, its *real* full chroma resolution is about 1600x1200. The
rest comes from, essentially, a form of spectral interpolation.

http://en.wikipedia.org/wiki/Demosaicing
http://web.cecs.pdx.edu/~cklin/demosaic/

There are some examples of CCDs that instead work in a layered fashion.
Foveon are well known for producing such a sensor. In their designs, red,
green and blue pixels are aligned above one another, each capturing one
part of the spectrum but transmitting the remainder to the next plane.
Foveon sensors are in the Sigma SD9 and SD10 DSLR cameras. The cameras
capture an image area of ~3.3MP in full colour. This amounts to 3 x 3.3MP
per colour component, so Foveon often advertise the sensor as a 10MP
unit. People have, remarkably, complained that this is misleading, even
though anyone making a Bayer sensor with a 10MP capture area and 10MP
announced resolution is doing the same thing.

http://www.x3f.info/technotes/x3pixel/pixelpage.html
http://www.foveon.com/
http://www.sigma-photo.co.jp/english...ital/sd_10.htm

Ignoring issues with Sigma's camera design or low light noise levels with
the Foveon sensor, the lack of interpolation produces some stunning
images. The results are predictably impressive with scenes that cause
Bayer sensors a lot of trouble. Landscapes are an example, because trees
and other foliage remain extremely detailed rather than being turned to
mush by the demosaic process. Dark, sharp lines against bright
backgrounds (e.g. wires or branches against sky) do well because of the
lack of the in-camera sharpening. That's required with Bayer sensor
designs because it hides the fact that the interpolated image can look
pretty soft without it - now you know why some cameras have a sharpening
level setting available in their menus.

Some high end stills gear uses devices from Foveon or akin to the Foveon
capture method. It may be the same with more expensive digital video
cameras, or they could capture at well above 1280x720 resolution and
convert down so that each pixel really is full colour rather than the
result of an interpolation process (2x2 RGB[G] clusters to 1x1 full
colour pixel, say).

This means that 720p pictures cannot be interpolated to fit on a 1920x1080
monitor without causing red and blue fringes to appear

This would be true, but indeed, the reason why red and blue fringes
*don't* appear when 720p images are thus scaled is because 720p digital
video cameras do not work as you expected.

--
TTFN, Andrew Hodgkinson
Find some electronic music at: Photos, wallpaper, software and mo
http://pond.org.uk/music.html http://pond.org.uk/

Agamemnon wrote:
Yesterday night I installed Internet Explorer 7 and when I ran it it went to



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PART TIME SEASONAL WORK ADDRESS


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Appears on the UK child sex offenders register

"♥ Marjo Xenos loves Degni Filio ♥" wrote in message
oups.com...



Sean Ruttledge is a psychopathically racist Irish provo usnet troll who is
now a Muslim convert married to a Turkish child wife that has plagued Greek
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who post in these groups. He is the kind of fanatical scum that turned into
the July 7 bombers and his mission in life is to spread hate. He even has
his own asshole's group alt.asshole.sean-ruttledge dedicated to him.

Send complaints about his trolling to: ,
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and report him to the Internet Watch Foundation
http://www.iwf.org.uk/reporting.htm so we can get rid of him.


F'ups set to alt.asshole.sean-ruttledge

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Agamemnon wrote:
Yesterday night I installed Internet Explorer 7 and when I ran it it went
to

"Andrew Hodgkinson" wrote in message
...
Agamemnon wrote:

[...] because such a camera must work in the same way as Microsoft
ClearType. When the image is projected by the camera lens on the CCD the
individual Red, Green and Blue subpixels on the CCD will see the picture
just like Clear Type.

Digital image capture devices do not have to work like ClearType at all.

As you correctly stated, many digital cameras, still or moving, use
individual RGB pixels - usually in groups of 4, often with an extra green
pixel or in some cases another colour like Cyan. These do capture, in raw
format, in the manner you describe. However inside the camera, a demosaic
algorithm converts the raw data from the 2x2 groups of RGB[G] pixels into
individual pixels of a full colour image. In the case of digital video
capture devices, this happens in real time, per frame. Yes, this means
that if I have, say, a 3200x2400 image from an ~8MP conventional digital
stills camera, its *real* full chroma resolution is about 1600x1200. The
rest comes from, essentially, a form of spectral interpolation.

http://en.wikipedia.org/wiki/Demosaicing
http://web.cecs.pdx.edu/~cklin/demosaic/

There are some examples of CCDs that instead work in a layered fashion.
Foveon are well known for producing such a sensor. In their designs, red,
green and blue pixels are aligned above one another, each capturing one
part of the spectrum but transmitting the remainder to the next plane.
Foveon sensors are in the Sigma SD9 and SD10 DSLR cameras. The cameras
capture an image area of ~3.3MP in full colour. This amounts to 3 x 3.3MP
per colour component, so Foveon often advertise the sensor as a 10MP unit.
People have, remarkably, complained that this is misleading, even though
anyone making a Bayer sensor with a 10MP capture area and 10MP announced
resolution is doing the same thing.

http://www.x3f.info/technotes/x3pixel/pixelpage.html
http://www.foveon.com/
http://www.sigma-photo.co.jp/english...ital/sd_10.htm

Ignoring issues with Sigma's camera design or low light noise levels with
the Foveon sensor, the lack of interpolation produces some stunning
images. The results are predictably impressive with scenes that cause
Bayer sensors a lot of trouble. Landscapes are an example, because trees
and other foliage remain extremely detailed rather than being turned to
mush by the demosaic process. Dark, sharp lines against bright

Ah... so that explains the mess my sisters 6MP camera made of the grass on
the lawn and the garden soil in front of it when I took a photo of the
garden to test the camera from two and a half stories above, although the
other pictures it took looked fine. All of the bright areas on the grass and
on the top of the soil were way to bright in comparison to the dark areas.
Or maybe these kind of cameras should use 10 bits per pixel instead and then
dither the image to 8 bits per pixel to give a better dynamic range.

backgrounds (e.g. wires or branches against sky) do well because of the
lack of the in-camera sharpening. That's required with Bayer sensor
designs because it hides the fact that the interpolated image can look
pretty soft without it - now you know why some cameras have a sharpening
level setting available in their menus.

Some high end stills gear uses devices from Foveon or akin to the Foveon
capture method. It may be the same with more expensive digital video
cameras, or they could capture at well above 1280x720 resolution and
convert down so that each pixel really is full colour rather than the
result of an interpolation process (2x2 RGB[G] clusters to 1x1 full colour
pixel, say).

This means that 720p pictures cannot be interpolated to fit on a
1920x1080 monitor without causing red and blue fringes to appear

This would be true, but indeed, the reason why red and blue fringes
*don't* appear when 720p images are thus scaled is because 720p digital
video cameras do not work as you expected.

--
TTFN, Andrew Hodgkinson
Find some electronic music at: Photos, wallpaper, software and mo
http://pond.org.uk/music.html http://pond.org.uk/