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pixel shape ?

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Anonymous
January 19, 2005 3:08:32 PM

Archived from groups: rec.video.desktop (More info?)

I have seen discussions in some computer graphic forums where the
argument is about the image size to create for use in video for burning
to DVD.

The issue seems to be that TV uses a square pixel and computer monitors
use a rectangular pixel (or vice versa). Therefore a tv image on a
computer should look stretched on a computer and squashed if computer
generated to TV.

Can anyone clarify or point me to a resource ?

More about : pixel shape

Anonymous
January 19, 2005 5:31:53 PM

Archived from groups: rec.video.desktop (More info?)

It isn't the monitor, it's the resolution. Given that the monitor is
usually 4:3, it depends on the resolution as to what the pixel aspect
ratio ends up being. For example, 1024x768 on a 4:3 monitor results in
square pixels. However, 1280x1024 on the same monitor does not result
in square pixels. Many plasma displays that are 16:9 run at various
resolutions that don't result in square pixels.
Anonymous
January 19, 2005 8:30:27 PM

Archived from groups: rec.video.desktop (More info?)

nap wrote:
> "FLY135" <fly_135@hotmail.com> wrote in message
> news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
> > It isn't the monitor, it's the resolution. Given that the monitor
is
> > usually 4:3, it depends on the resolution as to what the pixel
aspect
> > ratio ends up being. For example, 1024x768 on a 4:3 monitor
results in
> > square pixels. However, 1280x1024 on the same monitor does not
result
> > in square pixels. Many plasma displays that are 16:9 run at
various
> > resolutions that don't result in square pixels.
> >
>
> exactly. .And since NTSC is NOT a pixel display it can not be said
that
> they are square OR rectangular.

I have been using a computer for years for preparing computer generated
lead-in and titling and have never really noticed a problem. I started
questioning it because of comments that you needed to compensate for
it. I used to do 800 x 600 avi files and changed by request to 720 x
480. 720 x 480 seems to be a standard for video editing software but
is not a 4:3 ratio.

I will have a look at the sites listed

thanks .
Related resources
Anonymous
January 20, 2005 12:05:02 AM

Archived from groups: rec.video.desktop (More info?)

marks542004@yahoo.com wrote:

> I have seen discussions in some computer graphic forums where the
> argument is about the image size to create for use in video for burning
> to DVD.
>
> The issue seems to be that TV uses a square pixel and computer monitors
> use a rectangular pixel (or vice versa). Therefore a tv image on a
> computer should look stretched on a computer and squashed if computer
> generated to TV.
>
> Can anyone clarify or point me to a resource ?

You've pretty much summed it up in your post here. And, yes a tv image
looking at it on a monitor will look stretched.

http://www.lurkertech.com/lg/pixelaspect.html
http://www.adobe.com/support/techdocs/322300.html
http://www.larryjordan.biz/articles/lj_pixels.html

Also.. you can adjust for this in PhotoShop CS too. It has the ability
to work in non square environment.

-Richard
Anonymous
January 20, 2005 12:26:39 AM

Archived from groups: rec.video.desktop (More info?)

Are you sure that's right? Not every video format is rectangular, so..
And I don't think you can simply state that all computer monitors are
rectangular


"Richard Ragon" <bsema04@hananho.com> wrote in message
news:2YzHd.13197$5R.6177@newssvr21.news.prodigy.com...
> marks542004@yahoo.com wrote:
>
>> I have seen discussions in some computer graphic forums where the
>> argument is about the image size to create for use in video for burning
>> to DVD.
>>
>> The issue seems to be that TV uses a square pixel and computer monitors
>> use a rectangular pixel (or vice versa). Therefore a tv image on a
>> computer should look stretched on a computer and squashed if computer
>> generated to TV.
>>
>> Can anyone clarify or point me to a resource ?
>
> You've pretty much summed it up in your post here. And, yes a tv image
> looking at it on a monitor will look stretched.
>
> http://www.lurkertech.com/lg/pixelaspect.html
> http://www.adobe.com/support/techdocs/322300.html
> http://www.larryjordan.biz/articles/lj_pixels.html
>
> Also.. you can adjust for this in PhotoShop CS too. It has the ability to
> work in non square environment.
>
> -Richard
>
Anonymous
January 20, 2005 12:47:07 AM

Archived from groups: rec.video.desktop (More info?)

nap wrote:

> Are you sure that's right? Not every video format is rectangular, so..
> And I don't think you can simply state that all computer monitors are
> rectangular

That's true.. HD uses square pixels. However, I don't know a single
monitor that doesn't use square pixels.. Are there?

-Richard



> "Richard Ragon" <bsema04@hananho.com> wrote in message
> news:2YzHd.13197$5R.6177@newssvr21.news.prodigy.com...
>
>>marks542004@yahoo.com wrote:
>>
>>
>>>I have seen discussions in some computer graphic forums where the
>>>argument is about the image size to create for use in video for burning
>>>to DVD.
>>>
>>>The issue seems to be that TV uses a square pixel and computer monitors
>>>use a rectangular pixel (or vice versa). Therefore a tv image on a
>>>computer should look stretched on a computer and squashed if computer
>>>generated to TV.
>>>
>>>Can anyone clarify or point me to a resource ?
>>
>>You've pretty much summed it up in your post here. And, yes a tv image
>>looking at it on a monitor will look stretched.
>>
>>http://www.lurkertech.com/lg/pixelaspect.html
>>http://www.adobe.com/support/techdocs/322300.html
>>http://www.larryjordan.biz/articles/lj_pixels.html
>>
>>Also.. you can adjust for this in PhotoShop CS too. It has the ability to
>>work in non square environment.
>>
>>-Richard
Anonymous
January 20, 2005 2:04:46 AM

Archived from groups: rec.video.desktop (More info?)

"FLY135" <fly_135@hotmail.com> wrote in message
news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
> It isn't the monitor, it's the resolution. Given that the monitor is
> usually 4:3, it depends on the resolution as to what the pixel aspect
> ratio ends up being. For example, 1024x768 on a 4:3 monitor results in
> square pixels. However, 1280x1024 on the same monitor does not result
> in square pixels. Many plasma displays that are 16:9 run at various
> resolutions that don't result in square pixels.
>

exactly. .And since NTSC is NOT a pixel display it can not be said that
they are square OR rectangular.
Anonymous
January 20, 2005 4:35:12 AM

Archived from groups: rec.video.desktop (More info?)

<marks542004@yahoo.com> wrote in message
news:1106184627.152028.200340@z14g2000cwz.googlegroups.com...
>
> nap wrote:
>> "FLY135" <fly_135@hotmail.com> wrote in message
>> news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
>> > It isn't the monitor, it's the resolution. Given that the monitor
> is
>> > usually 4:3, it depends on the resolution as to what the pixel
> aspect
>> > ratio ends up being. For example, 1024x768 on a 4:3 monitor
> results in
>> > square pixels. However, 1280x1024 on the same monitor does not
> result
>> > in square pixels. Many plasma displays that are 16:9 run at
> various
>> > resolutions that don't result in square pixels.
>> >
>>
>> exactly. .And since NTSC is NOT a pixel display it can not be said
> that
>> they are square OR rectangular.
>
> I have been using a computer for years for preparing computer generated
> lead-in and titling and have never really noticed a problem. I started
> questioning it because of comments that you needed to compensate for
> it. I used to do 800 x 600 avi files and changed by request to 720 x
> 480. 720 x 480 seems to be a standard for video editing software but
> is not a 4:3 ratio.
>
> I will have a look at the sites listed
>
> thanks .
>


There are many sites which discuss how to generate graphics in square pixel
apps for rect. pixel displays. google is your friend.
Anonymous
January 20, 2005 4:55:34 AM

Archived from groups: rec.video.desktop (More info?)

"nap" <gospam@yourself.com> wrote in message
news:iIBHd.13252$5R.12455@newssvr21.news.prodigy.com...
> "FLY135" <fly_135@hotmail.com> wrote in message
> news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
> > It isn't the monitor, it's the resolution. Given that the monitor is
> > usually 4:3, it depends on the resolution as to what the pixel aspect
> > ratio ends up being. For example, 1024x768 on a 4:3 monitor results in
> > square pixels. However, 1280x1024 on the same monitor does not result
> > in square pixels. Many plasma displays that are 16:9 run at various
> > resolutions that don't result in square pixels.
> >
>
> exactly. .And since NTSC is NOT a pixel display it can not be said that
> they are square OR rectangular.

The pixel aspect is a valid consideration whether it's a computer monitor or
an NTSC TV. The MPEG videos played by a DVD player are clocked out as
pixels and then encoded into NTSC. So "technically" the OP was incorrect in
saying that TV's use any particular shape of pixel. But the same can be
said about a computer monitor. It is also analog and does not actually use
pixels.

It's the hardware generating the video signal, whether it's encoded into
NTSC or output as analog RGB that is what we are speaking of when refering
to pixels. The difference is that the video generated for a computer
monitor virtually always comes from a pixel oriented source where NTSC
frequently does not.
Anonymous
January 20, 2005 4:56:42 AM

Archived from groups: rec.video.desktop (More info?)

"nap" <gospam@yourself.com> wrote in message
news:jgAHd.13212$5R.387@newssvr21.news.prodigy.com...
> Are you sure that's right? Not every video format is rectangular, so..
> And I don't think you can simply state that all computer monitors are
> rectangular

All the ones I've seen are.
Anonymous
January 20, 2005 10:34:09 AM

Archived from groups: rec.video.desktop (More info?)

<marks542004@yahoo.com> schreef in bericht
news:1106184627.152028.200340@z14g2000cwz.googlegroups.com...
>
> nap wrote:
>> "FLY135" <fly_135@hotmail.com> wrote in message
>> news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
>> > It isn't the monitor, it's the resolution. Given that the monitor
> is
>> > usually 4:3, it depends on the resolution as to what the pixel
> aspect
>> > ratio ends up being. For example, 1024x768 on a 4:3 monitor
> results in
>> > square pixels. However, 1280x1024 on the same monitor does not
> result
>> > in square pixels. Many plasma displays that are 16:9 run at
> various
>> > resolutions that don't result in square pixels.
>> >
>>
>> exactly. .And since NTSC is NOT a pixel display it can not be said
> that
>> they are square OR rectangular.
>
> I have been using a computer for years for preparing computer generated
> lead-in and titling and have never really noticed a problem. I started
> questioning it because of comments that you needed to compensate for
> it. I used to do 800 x 600 avi files and changed by request to 720 x
> 480. 720 x 480 seems to be a standard for video editing software but
> is not a 4:3 ratio.

The 720 x 480 matrix (or 720 x 576 for PAL) is the standard for putting
video images on DVD. So, the way you have been working is correct. These
standard matrices are not 4:3 but are converted by the DVD player to a 4:3
video signal. Even 16:9 widescreen images are recorded in this 720 x 480/576
matrix and then converted by the player to a 16:9 signal. In the last case
you would therefore need to prepare your graphics for NTSC in say 853 x 480
and shrink them horizontally to 720 x 480 to be included in the video.
However, you have to make sure that the editing software imports images on a
pixel by pixel basis and doesn't do any conversion itself.
--
Lou van Wijhe
Website: http://home.hccnet.nl/jl.van.wijhe/
AntiSpam: Vervang INVALID in e-mail adres door NL
AntiSpam: Replace INVALID in e-mail address by NL
Anonymous
January 20, 2005 11:10:01 AM

Archived from groups: rec.video.desktop (More info?)

dv video is 720x480, when creating graphics in Photoshop for use in
that timeline, create them 720x540 as PS uses square pixels versus the
non-square DV.
Anonymous
January 21, 2005 1:09:01 AM

Archived from groups: rec.video.desktop (More info?)

"FLY135" <FLY_135(@hot not not)notmail.com> wrote in message
news:udEHd.1082$cZ1.845@newsread2.news.atl.earthlink.net...
>
> "nap" <gospam@yourself.com> wrote in message
> news:jgAHd.13212$5R.387@newssvr21.news.prodigy.com...
>> Are you sure that's right? Not every video format is rectangular, so..
>> And I don't think you can simply state that all computer monitors are
>> rectangular
>
> All the ones I've seen are.
>
>

Has anyone mentioned the utility called "Aspect", yet?
www.aspect.fre3.com (turn on your pop-up stopper
first)

Luck;
Ken
Anonymous
January 21, 2005 2:20:22 AM

Archived from groups: rec.video.desktop (More info?)

"FLY135" <fly_135@hotmail.com> wrote in message
news:1106173913.336834.125010@c13g2000cwb.googlegroups.com...
> It isn't the monitor, it's the resolution. Given that the monitor is
> usually 4:3, it depends on the resolution as to what the pixel aspect
> ratio ends up being. For example, 1024x768 on a 4:3 monitor results in
> square pixels. However, 1280x1024 on the same monitor does not result
> in square pixels. Many plasma displays that are 16:9 run at various
> resolutions that don't result in square pixels.
>

I'm not particularly convinced that just because a screen resolution is not
4:3 the pixel is not also square. I do see the logic in that the true 4:3
ratio would be 1280x960 rather than 1280x1024. This is true the 1280x1024 is
not 4:3. I had conversation on another forum with someone having trouble
with the Edius interface on a single LCD monitor only capable of 1280x1024
max. It seems due to the natural way the program opens is meant for dual
monitors and it was frustrating him. I did a reshuffle of the interface
within 1280x1024 for him and sent this link for hime to see:
http://digitalvideosolutions.com/photos/Edius.jpg

After reading this thread on 4:3 ratio and resolutions, I wanted to see what
the true pixel shape was of this screen cap. I used a generic screen capture
program and told it to capture the full screen. I made no other changes to
the natural way it captured the image, other than to tell it to save in the
JPG format at the highest quality possible. I just went to Photoshop CS,
which has a pixel ratio management module, to see what it said about the
pixel ratio of that image. Photoshop CS reports it has 'square pixels' in
its' natural state. Check it for yourself.

If the assumption holds true that using ratios other than 4:3 changes the
pixel ratio it surely would show in this images' properties. My assumption
is that the pixel stays square regardless of the screen resolution because
the screen itself has no pixels to be squared or rectangled in the first
place, it is only the resultant image made from or in those resolutions on
the computer which are generated in square pixel. Just for grins I would try
some screen caps in all sorts of odd-ball resolutions to see if the pixel
every changes.

With digital video it is the device that creates the native pixel 0.9. On
the computer most software read and translate to square. What the original
postee was asking about was obviously DV because analog video is square
pixel when capture with non-DV ready equipment, and DV video does wide on
the computer screen due to the native pixel ratio of DV.

As for what the original person asked, there are seveal ways to combat the
differences in pixel shape. One I have seen used is this, if you generate a
graphic which is a true 4:3 at 720x540 then squeeze this into the confines
of the DV framework 720x480 0.9 pixel it should look absolutely fine when
output on a television screen. You can test the theory for yourself by
creating this size image with a circular object in the center of the screen,
and another using 720x480 square pixel. Place them side by side and create a
looping video of them, then output them to a miniDV tape or as a squence
onto a DVD rewritable for playback on a television monitor for comparison.

Adobe Photoshop CS allows you to change the pixel from square to D1/DV 0.9
just for reference.
--
Larry Johnson
Digital Video Solutions
webmaster@digitalvideosolutions.com
http://www.digitalvideosolutions.com
877-227-6281 Toll Free Sales Assistance
386-672-1941 Customer Service
386-672-1907 Technical Support
386-676-1515 Fax
Anonymous
January 21, 2005 4:18:09 AM

Archived from groups: rec.video.desktop (More info?)

"Digital Video Solutions" <video@digitalvideosolutionsNOSPAM.com> wrote in
message news:W0XHd.211204$8G4.99103@tornado.tampabay.rr.com...
> With digital video it is the device that creates the native pixel 0.9. On
> the computer most software read and translate to square. What the original
> postee was asking about was obviously DV because analog video is square
> pixel when capture with non-DV ready equipment, and DV video does wide on
> the computer screen due to the native pixel ratio of DV.

I think your talking apples and oranges here. Just because an image is
reported as say... 72dpi, that doesn't mean that it is actually 72 pixels
per inch on the screen.

The OP was talking about the fact that pixel aspect ratios vary between
computer oriented images and tv oriented images. This is correct. Square
pixels on computer displays occur when both the monitor is 4:3 (vs. say wide
screens that are now available) and the display resolution is set to a 4:3
aspect (like 800x600). However you can monkey with the sizing controls and
make this visually incorrect. You can also make it visually incorrect by
selecting a non 4:3 resolution if you are assuming that the pixels are
square no matter what.

> If the assumption holds true that using ratios other than 4:3 changes the
> pixel ratio it surely would show in this images' properties.

This only means that the software does not take into account the screen
resolution and apparently thinks that the computers pixels are by default
square.

> My assumption
> is that the pixel stays square regardless of the screen resolution because
> the screen itself has no pixels to be squared or rectangled in the first
> place, it is only the resultant image made from or in those resolutions on
> the computer which are generated in square pixel.

If a tree falls in the forest and no one is there to observe it, did it
really fall?

> Just for grins I would try
> some screen caps in all sorts of odd-ball resolutions to see if the pixel
> every changes.

It simple math... If your screen display is measurably 4:3 and your
resolution is not 4:3, then an image that is square pixel will not display
correctly unless your software knows your display is 4:3 and uses the
current resolution to rescale the display window to correct for the non 4:3
resolution.

> What the original
> postee was asking about was obviously DV because analog video is square
> pixel when capture with non-DV ready equipment, and DV video does wide on
> the computer screen due to the native pixel ratio of DV.

Sorry I cannot parse this statement.

> graphic which is a true 4:3 at 720x540 then squeeze this into the confines
> of the DV framework 720x480 0.9 pixel it should look absolutely fine when
> output on a television screen. You can test the theory for yourself by
> creating this size image with a circular object in the center of the
screen,

Yes, the math would indicate this to be true (480/540 = 0.88888). Which is
the same as (480 *4)/(720 * 3) = 0.8888.
Anonymous
January 23, 2005 8:44:42 AM

Archived from groups: rec.video.desktop (More info?)

"FLY135" <fly_135@(hot not not)notmail.com> wrote in message
news:lLYHd.2541$rp1.625@newsread3.news.atl.earthlink.net...
>
> "Digital Video Solutions" <video@digitalvideosolutionsNOSPAM.com> wrote in
> message news:W0XHd.211204$8G4.99103@tornado.tampabay.rr.com...
> > With digital video it is the device that creates the native pixel 0.9.
On
> > the computer most software read and translate to square. What the
original
> > postee was asking about was obviously DV because analog video is square
> > pixel when capture with non-DV ready equipment, and DV video does wide
on
> > the computer screen due to the native pixel ratio of DV.
>
> I think your talking apples and oranges here. Just because an image is
> reported as say... 72dpi, that doesn't mean that it is actually 72 pixels
> per inch on the screen.
>

Not once did I bring the dpi of a photo into the discussion. Since a DV
frame has no dpi then bringing dpi into the mix is a moot point.

> The OP was talking about the fact that pixel aspect ratios vary between
> computer oriented images and tv oriented images. This is correct. Square
> pixels on computer displays occur when both the monitor is 4:3 (vs. say
wide
> screens that are now available) and the display resolution is set to a 4:3
> aspect (like 800x600). However you can monkey with the sizing controls
and
> make this visually incorrect. You can also make it visually incorrect by
> selecting a non 4:3 resolution if you are assuming that the pixels are
> square no matter what.
>

Though it is possible to use programs such as Photoshop CS to alter the
pixel shape of an image, it still holds true that no matter what the screen
resolution a capture of that computer screen to a bitmapped image will in
fact have square pixels regardless of the resolutions of the computer screen
proper. Take any screen capture program like Solid Capture and set your
monitor to any resolution you wish. Set the program to capture the entire
screen in matching resolutions. Now, get any image editing program and look
at the properties - it says square pixels.

By using your earlier logic of dpi - "Just because an image is reported as
72dpi doesnt mean it is actually 72 pixels per inch on the screen" - gee
whiz! that was a true lightning bolt of knowledge by the way! Anyway, using
that logic then just because an image editing program report square pixels
does not mean the image actually has square pixels. Why not take that logic
a little further? Just because all editing programs say DV is 0.9 pixel
doesn't mean it is right. The only monkeying around here is your pretzel
logic in attemtping to convince everyone a monitors' resolution changes the
pixel ratio of the resultant captured image of that very screen resolution
no matter what resolution is chosen!

> > If the assumption holds true that using ratios other than 4:3 changes
the
> > pixel ratio it surely would show in this images' properties.
>
> This only means that the software does not take into account the screen
> resolution and apparently thinks that the computers pixels are by default
> square.
>
> > My assumption
> > is that the pixel stays square regardless of the screen resolution
because
> > the screen itself has no pixels to be squared or rectangled in the
first
> > place, it is only the resultant image made from or in those resolutions
on
> > the computer which are generated in square pixel.
>
> If a tree falls in the forest and no one is there to observe it, did it
> really fall?
>

Look, you aren't some zen master, and yes the tree falls whether anyone is
there to see it or not. If it didn't fall why is it on the ground to be seen
in the first place? The true question is not about a falling tree and
whether someone was there to observe it. Where have you been? The question
is "If a tree falls and no one is there to hear it does it really make a
sound?"

> > Just for grins I would try
> > some screen caps in all sorts of odd-ball resolutions to see if the
pixel
> > every changes.
>
> It simple math... If your screen display is measurably 4:3 and your
> resolution is not 4:3, then an image that is square pixel will not display
> correctly unless your software knows your display is 4:3 and uses the
> current resolution to rescale the display window to correct for the non
4:3
> resolution.
>
> > What the original
> > postee was asking about was obviously DV because analog video is square
> > pixel when capture with non-DV ready equipment, and DV video does wide
on
> > the computer screen due to the native pixel ratio of DV.
>
> Sorry I cannot parse this statement.
>
> > graphic which is a true 4:3 at 720x540 then squeeze this into the
confines
> > of the DV framework 720x480 0.9 pixel it should look absolutely fine
when
> > output on a television screen. You can test the theory for yourself by
> > creating this size image with a circular object in the center of the
> screen,
>
> Yes, the math would indicate this to be true (480/540 = 0.88888). Which
is
> the same as (480 *4)/(720 * 3) = 0.8888.

Duh, the math behind the squeeze. You have proven you can use a calculator.
Thank you for that.
Anonymous
January 23, 2005 2:47:39 PM

Archived from groups: rec.video.desktop (More info?)

The 72dpi reference had to do with the fact that the attributes of an
image don't necessarily match what you see on the screen. The point
being that you seem to be advocating that if a program such as
Photoshop says an image is square pixel then it must be true. If
Photoshop captures an image that is being displayed correctly in a
screen resolution that isn't square pixel and then it stores an
attribute with the image that says it is square pixel, then Photoshop
is not giving you the correct information.

If my comments seem "zen like" and I seem to be using "pretzel logic",
it's because I didn't know how to respond to the assertion that screens
don't have pixels and therefore what you see doesn't have to match what
Photoshop tells you. The resultant image is solely dependant on the
screen aspect, resolution aspect, the image's pixel aspect, and the
ability of the application to take those into account and properly
rescaling the image for display.

And yes, I can use a calculator. But knowing how to use a calculator
doesn't mean you can actually calculate anything. You don't need an
editing program to tell you the aspect of a DV pixel, you need to know
how to formulate the equation. And that equation takes into account
the screen aspect and resolution aspect. If they don't calculate to
square pixels on a properly displayed image, then the pixel aspect
isn't square no matter what Photoshop says.
!