Colour bleed

[David Deehan]

Hi,

This is the first time I have posted to this forum and being a novice with DV technology I do so with a little trepidation.

Last September I purchased a Sony TRV25. I was extremely impressed with this little camcorder however, in December I decided to take the plunge and upgrade further to an XM2. Anyway, my concern is as follows. After two months of testing the XM2 and comparing its results with those of the Sony there is one area where the Sony excels, namely lack of colour bleed.

I have posted some captured frames, which I think demonstrate this effect. These can be viewed at
http://homepage.ntlworld.com/david.d...XM2/index.htmlBy the way this web page is another first for me so here’s hoping it works OK.

In a recent thread Davide Manni (GL” Red Push Problem) mentioned the site http://www.gl1-411.com/forum/message...essageID=1473.This seems to reflect the same problem.

Any help would be greatly appreciated.

David

[Don Palomaki]

Can you please tell us how the images were captured and prepared for the web?

[Ken Tanaka]

As Don noted, we really need to know more about (a) how you shot the samples and, more importantly (b) how you prepared these graphics.

I noticed that your samples are JPEG's. One of the unusual collateral aspects of compressing an interlaced image with this method is that the algorithm can "smear" edges where it finds motion comb.

BTW, regarding the message on the other site that you referrred us to, just for the record the poster's allusion to Canon's pixel shift contributing to such an effect is misinformed. "Pixel shift" deals with a diffferent aspect of the image.

Certainly, I am not saying that you aren't seeing what you claim. We just need to know more about where you're really seeing it and how you're using the camera's controls.

Welcome again, David!

[Lars Siden]

Hello David,

I'm only guessing here ( my main knowledge is digital-still pictures, using the Canon D30 ).

Have you gained the color ? ( in the color gain menu ? ) if so, maybe you have gained it too much. Red is a sensitive colour.

Have you changed the sharpness settings on the camera? If you have "softened" the picture, try to sharpen it, or vice versa.

Did you use a program mode on the camera? Or where you on manual settings? Did you use a light-profile ( indoor/outdoor/tungsten etc ) or did you calibrate the whitebalance manually?

Hope these questions can help you try more ways of fixing the colourbleed.

Best regards,

Lars Siden

Stockholm, Sweden

[Andre De Clercq]

Several elements come into play:
-Camera type (pixel shift...)
-Color encoder (NTSC/PAL) quality
-Saturation level
-Y/C delay
-Display decoder (PAL/NTSC) Quality
-DV codec (NTSC 4:1:1) which lowers Hor color res to 25% of luma
(means color leakage)
To verify the original footage one should playback on a DV component player and go straight into a component display in order to avoid/exclude the color encoder/decoder shortcommings

[David Deehan]

Thanks for all the replies.

Here is some detail of the camera settings, video and still capture configuration, etc.

Camera settings:
XM2 - Pal
Camera mode – Normal
Recording program – TV (shutter speed 120)
White balance – Automatic
Optical stabilizer – On
Auto exposure – On (i.e. exposure lock off)
Auto focus – On
White balance – Auto
AE shift – default
Color Gain – default
Sharpness – increased 1 point
Setup Level – decreased 2 points

A UV filter is attached.

Video capture:
Hardware – firewire, Pentium IV – 2GHz, Matrox G400 video card, Iiyama 19” monitor.
Software – Vegas Video, Windows XP.


Still capture:
Frames were captured with Vegas Video clipboard capture facility and pasted into Paint Shop Pro
Original clips were used (no compression or deinterlacing)


Earlier today I played the clip (in windows Media Player) from which Smeared Image 2 was captured (see web page address in original post). I paused this clip and compared the frame side by side with the captured JPEG. The smearing artefacts were identical on both.

I also did the above comparison using a laptop with TFT display and achieved similar results.

I haven’t as yet watched any of these clips on television as its poorer resolution would probably mask much of the bleeding. I’ll probably do that tonight after work.

Thanks again,

David

[Lars Siden]

Hello David,

I see nothing strange in your setup. The only thing that strikes me as possible is that your version of Vegas(or some other Video editing software ) has changed your windows DV drivers. If possible, try to transfer some video to another machine, and see if the bleeding is still there ... if so - get it a plaster *grin*

// Lazze

[Tom Christensen]

I asked the same question when I experienced this on my GL2 and I got the same responses on this board.

http://www.dvinfo.net/conf/showthread.php?s=&threadid=4970&highlight=red+ghosting

Put a piece of red tape on a white background and you'll really get the effect (and probably get more annoyed like I did).


I usually try to turn down the color gain a bit and be aware when shooting anything red/orange.

I've learned to live with it because I really like the camera, but it is annoying since my 1ccd Sony doesn't seem to have this problem.

Tom

[Rob Lohman]

I have some problems with reds on my XL1s as well (striping
and same kind of bleeding as you do).. Seems to be isolated
to the reds..... Funny thing is that whenever I encode it to MPEG2
it seems to be gone. Weird.

[David Deehan]

I see Tom Christensen has mentioned this problem in another thread. If it’s a specific effect restricted to the pixel shift technology used in Canon cams, I’m surprised it hasn’t been highlighted more often. I’m also surprised not seeing it mentioned in any reviews. It may have swayed my buying decision towards a Sony model. I can concur with the end of Tom’s final sentence – “my 1ccd Sony doesn't seem to have this problem”. My previous Sony TRV25 did not show any bleeding effects.

I also agree with Tom’s observation in the thread http://www.dvinfo.net/conf/showthread.php?s=&threadid=4970&highlight=red+ghosting , “I tried the red tape on a white and then black background and Yikes!!!, fringing was very obvious. It became worse the farther away the tape was, so close up it was slight but moving away from the tape, the thing glowed.”

Since my last post I connected the XM2 to a television and observed the “bleeding” artefact. This would rule out computer hardware and software bugs.

Bleeding in the captured frame “Smeared Image 2” on my web site http://homepage.ntlworld.com/david.deehan/XM2/index.html is not restricted to “red”. Both “blue” (sign on wall) and “green” (post-box) also show signs of it.

The frames I have chosen were from clips handpicked to demonstrate the problem. These were extreme examples. Most of my filming to date does not show bleeding to such a degree; but is often there to a lesser degree. It seems to diminish image sharpness. I will turn down the colour gain and see what happens.

Anyway, its Friday night so I’m of to the bar!!!

Thanks for all your comments,

David

[Jeff Donald]

Try the 85B filter it works to lessen the problem in some of the DVX100 cameras. I have a client who swears by using the 85B the fringing is considerably lessened. There are plugins for FCP that may help also (if you use a Mac).

[Bud Kuenzli]

what plugins are you referring to for FCP and fringing?

[Gabriel_Knight]

The smearing of colors is very annoying, and I am glad this camera does not have a lot of smearing.

My previous camera (a Sony! TRV20) had a lot of smearing!
It was much worse than the XM2 I now have. When you tried to film a white duck in brown/black water, you will get a lot of smearing with the sony, but almost none with the XM2.

[Jeff Donald]

Joe's Filters has a Y/C filter to help with retiming color.

[David Deehan]

Hi everyone,

apologies for resurrecting this thread, but I’m about to contact Canon support prior to the expiry of the warranty. Since my last post in March I have updated my website ( http://homepage.ntlworld.com/david..../XM2/index.html ) with further images demonstrating colour bleed – namely “Smeared Image 3” and 6 new image links at the bottom of the page. I would welcome any comments explaining why the chroma shift is always to the left and bottom of each image.

David