XL1-S Vertical Distortion at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon XL1S / XL1 Watchdog

Canon XL1S / XL1 Watchdog
Can't find it on the XL1 Watchdog site? Discuss it here.


Reply
 
Thread Tools Search this Thread
Old April 30th, 2005, 01:46 PM   #1
Regular Crew
 
Join Date: Mar 2005
Location: Hinckley UK
Posts: 25
XL1-S Vertical Distortion

I apologise if this has been covered elsewhere - but I have had a look and could not find it.

I have been trying to undertake some image analysis using my XL1-S.

Am I right in thinking that the CCD system stretches the image vertically by about 7%? Or to put it another way, the effective pitch of pixels in the vertical is not the same as the effective pitch of pixels in the horizontal?

I am using a PAL camera with the 3x lens in frame mode.

My subject was a perfect square, with the camera as close as possible to perpendicular on the centre point. I grabbed a 720x576 image (representing my understanding of the effective resolution of the CCD system), the square extending to near the top and bottom of the frame (with larger gaps to the sides of course)

I tried this with several camera distances, zoom levels, and even with the camera on its side - always the same result (or at last very close) - The square is appears to be stretched vertically by an average of about 7.2%.

Am I doing something strange? Are all cameras like this? Or just the XL1-S? Or is it a result of using Frame mode?

Any comments gratefully received.
__________________
Richard M
Richard J Morris is offline   Reply With Quote
Old April 30th, 2005, 08:00 PM   #2
Major Player
 
Join Date: Nov 2003
Location: ontario
Posts: 445
Just curious, how did you determine that it was 7.2%?
Did you capture to something?
Jack Smith is offline   Reply With Quote
Old May 1st, 2005, 04:01 AM   #3
Regular Crew
 
Join Date: Mar 2005
Location: Hinckley UK
Posts: 25
I grabbed a 720 x 576 pixel bitmap image from the camera using Pinnacle Studio.

The image was of a square, 280mm x 280mm, printed on an A3 sheet with centre lines on the square aligned as close as possible to the centre of the image. I then counted the number of pixels along each centre line to the edges of the square.

My conclusion is that the effective pixel rows are squashed together slightly more than the effective pixel columns.

I tried it 5 times with the camera at different distances and zooms and even twice with the camera on its side - the results were pretty consistant.
__________________
Richard M
Richard J Morris is offline   Reply With Quote
Old May 2nd, 2005, 10:58 PM   #4
Major Player
 
Join Date: Nov 2003
Location: ontario
Posts: 445
Are you viewing this on a computer monitor?
The monitor will be resizing the image to fit. eg. monitor set to 800 x 600
the 720 is increased by about 111% ( 800 divide by 720)but the 576 is only increased by 104%(600 divide by 576)
so it will look squished , stretched out sideways.
Now 111 minus 104 is 7 but ............ just kidding
Jack Smith is offline   Reply With Quote
Old May 3rd, 2005, 07:04 AM   #5
Regular Crew
 
Join Date: Mar 2005
Location: Hinckley UK
Posts: 25
Hi Jack - thanks for the comments.

I am looking at the grabbed image on a monitor - but the pixels are indentified using the "Cursor:(x,y)" information at the bottom left corner of MS Photo Editor. This identifies the cursor position over a pixel in the bitmap image file, not the pixel on the screen - you can tell because zooming in and out in MSPE has no effect on cursor pixel status - so its not a monitor scaling issue.... I don't think....
__________________
Richard M
Richard J Morris is offline   Reply With Quote
Old May 3rd, 2005, 10:53 PM   #6
Major Player
 
Join Date: Nov 2003
Location: ontario
Posts: 445
I think you may still have resizing happening.The pixel identifier may be correct but they are resized to output to the monitor.try by creating a photo 720 x 576 in photoprogram and looking at that.or how about you load the grab onto the timeline and render to an dv avi then send it back to the camera then view it on TV and/or the viewfinder
Jack Smith is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon XL1S / XL1 Watchdog

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 10:17 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network