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measuring video resolution

Author
3 Apr 2007 10:29 PM
mofo22
I want to measure / compare the video resolution, in terms of tv
lines, of about a dozen different cameras. This is a test i need to do
for a project on video cameras. I am getting the cameras from various
distributors who claim various specs from their cameras. What is an
acurate way to do this? and is it possible to do it without breaking
the bank? I do not have the budget to buy expensive test devices. I
have seen charts designed to do this but, what do you all think?

Author
4 Apr 2007 5:51 PM
Gene E. Bloch
"mofo22" <onboar***@gmail.com> wrote in
news:1175639374.439696.155760@y66g2000hsf.googlegroups.com:

> I want to measure / compare the video resolution, in terms of tv
> lines, of about a dozen different cameras. This is a test i need
> to do for a project on video cameras. I am getting the cameras
> from various distributors who claim various specs from their
> cameras. What is an acurate way to do this? and is it possible to
> do it without breaking the bank? I do not have the budget to buy
> expensive test devices. I have seen charts designed to do this
> but, what do you all think?

I think you will work very hard to get very inconclusive results. I
think the differences will be slight and hard to discern.

In all seriousness, I'd suggest dropping this project for a different
one.

Flamers: I wouldn't blame  you for flaming me on this, but if I *am*
wrong, it would be better to give concrete and helpful advice to the OP
and just in passing point out that I'm being stupid - or at least
ignorant or prejudiced - here..

--
Gene E. Bloch (Gino) ... letters617blochg3251
(replace the numbers by "at" and "dotcom")
Author
4 Apr 2007 9:36 PM
Smarty
Here is the way one very traditional organization which does what you are
interested in doing with video cameras, in this case using a camera
resolution test chart defined by PIMA/ISO 12233. The approach for still and
video cameras is essentially the same.
http://www.dpreview.com/learn/?/Glossary/Digital_Imaging/Resolution_01.htm

There are also many other charts which can also be used, and they can be
seen and purchased from places like:

http://armstrongoptical.co.uk/6/StandardProductrange.html

Standard practice is to take cropped areas of interest from the camera's
captured image and compare / study them visually and draw conclusions.

The process is actually very inexpensive, requires little test "equipment",
but does rely on experience and judgment which you may lack at the
beginning. If you are mostly concerned with relative / comparative
performance (versus absolute measurements) then judgment will not be an
issue since the differences will become apparent as you look at crops side
by side.

Hope this helps,

Smarty

Show quoteHide quote
"mofo22" <onboar***@gmail.com> wrote in message
news:1175639374.439696.155760@y66g2000hsf.googlegroups.com...
>I want to measure / compare the video resolution, in terms of tv
> lines, of about a dozen different cameras. This is a test i need to do
> for a project on video cameras. I am getting the cameras from various
> distributors who claim various specs from their cameras. What is an
> acurate way to do this? and is it possible to do it without breaking
> the bank? I do not have the budget to buy expensive test devices. I
> have seen charts designed to do this but, what do you all think?
>
Author
5 Apr 2007 3:17 AM
100246.2055
On Apr 4, 9:29 am, "mofo22" <onboar***@gmail.com> wrote:
> I want to measure / compare the video resolution, in terms of tv
> lines, of about a dozen different cameras. This is a test i need to do
> for a project on video cameras. I am getting the cameras from various
> distributors who claim various specs from their cameras. What is an
> acurate way to do this? and is it possible to do it without breaking
> the bank? I do not have the budget to buy expensive test devices. I
> have seen charts designed to do this but, what do you all think?

Simply if you only wish to "measure" resolution in a simple and
comparative way without actual numeric readings what you
need is a "Multiburst" chart.
These are available from multiple sources
and are simply a chart with groups of vertical parallel lines with
decreasing spacing as you progress to the right of the chart.
The line spacings are chosen to represent different increasing
frequencies
in the video output from the camera when focussed on the chart.
You can get an idea of the resolution by looking on a monitor
and the group that is the last where the lines can be discerned
is the maximum frequency in the video.

If you have an oscilloscope or waveform monitor to look at the
video signal you can measure the drop-off in level at higher
frequencies.

Another chart but harder to come by is a "Sweep" chart where the
lines get progressively closer together and are not arranged in
groups.

There are also RETMA charts and other charts such as a Marconi No. 1
chart that have wedge shaped patterns that are calibrated in
"Lines per picture height" that are used in a similar way.

Have a look at this URL which gives some further information and links
to
places where you can download some charts for printing.
http://www.bealecorner.com/trv900/respat/