Mirage Recorder - Page 3 at DVinfo.net

Go Back   DV Info Net > Special Interest Areas > Alternative Imaging Methods

Alternative Imaging Methods
DV Info Net is the birthplace of all 35mm adapters.


Reply
 
Thread Tools Search this Thread
Old July 5th, 2007, 03:35 PM   #31
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Jose,

Are you sure your camera doesn't use some factory calibration data to compensate for non uniformity?
In any case I have contacted the reseller of the Pike, I wonder what they will reply.

Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 6th, 2007, 01:11 PM   #32
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Hi,

I contacted the dealer, and they have a firmware update for me to do.
So with a little bit of luck my fixed pattern noise will be over soon.

Now I'll have to get my hands on Windows Vista, as I can not update the firmware with Mac OS X. A little bit sad that I will have to get an OS just to upload firmware :-(

Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 12th, 2007, 01:02 AM   #33
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Hi, I measured the linearity of the sensor in the pike.
It seems that any value below 100 is trash, but above that it is linear. I guess it would be possible to use two flat field images to compensate for anything above 100. But I am scared that it won't look right, when clamping that much data.

here are the results from 10 neighboring green pixels in a single column. every forth pixel is to hot (thus three pixels in this case).

http://www.vosgames.nl/products/Mira...lLinearity.png
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 12th, 2007, 01:19 PM   #34
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
I've made an other measurement using the camera flash light (in continues mode) of my mobile phone. This makes for a much more stable measurement.

You can see here that 7 pixels are pretty much linear. But three pixels are slightly parabolic. I may be able to compensate for it.

I guess I will need to build some form of calibration light that can be screwed on the camera, to make it easy to do accurate automatic calibration.

http://www.vosgames.nl/products/Mira...Linearity2.png
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 28th, 2007, 12:55 PM   #35
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
It has been some time since I last posted, but I have an update.

I seem to have solved the dark pixel non uniformity, using a per-pixel 7 point lookup table with cubic interpolation.

However there are still some bugs in my code so I can not let you see a good image just yet.

Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 28th, 2007, 04:42 PM   #36
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
First good picture

Hello everyone,

I've been able to fix most of the problems now. Here is a picture of the results of today.
http://www.vosgames.nl/products/Mira...oodPicture.png

This algorithm includes bad pixel removal, marking of bad pixels is depended on brightness. So in dark patches more pixels are removed, this is to solve unfixable non-linearities.

It seems to not have solved all the double tap problems yet, which it should, maybe I need a more accurate LUT table at higher brightness levels.

Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old July 28th, 2007, 07:29 PM   #37
Major Player
 
Join Date: May 2007
Location: Sevilla (Spain)
Posts: 439
That image looks just great Take! Keep it up!
Jose A. Garcia is offline   Reply With Quote
Old July 28th, 2007, 11:01 PM   #38
Regular Crew
 
Join Date: Jan 2006
Location: Woodstock, Georgia
Posts: 154
Great job, thats a really smooth image :)
Solomon Chase is offline   Reply With Quote
Old August 7th, 2007, 12:51 AM   #39
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Balancing Solved

Hello everyone,

I've made a new picture, there isn't much sun as it is pretty early in the morning and overcast.

http://www.vosgames.nl/products/Mira...cingSolved.png

Here you can see that there is no longer any visible difference between the left and right side of the image.

I now use a 15 point LUT and separate average black left for the left and right side of the picture. The black level is first subtracted from the image before the 15 point LUT is applied. The black level does drift and right now you will have to manually (cover the lens, press button) measure this before each take. I hope with new firmware on the Pike I will be able to access the left and right light shielded pixels.

If one would look closely to flat field target with a flashlight pointing to it, I am seeing color banding. I am not sure why this is caused, maybe by the sharp edges in the LUT which would be solved by using cubic interpolation instead of linear interpolation.

I also like to mention that the 15 point LUT will now pull the pixel values to the theoretical linear photo response. I do this according to this formula:
when average intensity is around 90 %:
intensity_per_second = average_intensity[90] / shutter_time[90]

for all the measurements done I will calculate 0% <= k <= 100%:
theoretical_intensity[k] = intensity_per_second * shutter_time[k]


Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old August 7th, 2007, 01:17 PM   #40
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
I've made a new picture that was better calibrated.

http://www.vosgames.nl/products/Mira...ingSolved2.png

I've done some white balancing and set the black level lower (sun was shining into lens).
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old August 7th, 2007, 03:16 PM   #41
Regular Crew
 
Join Date: Jan 2006
Location: Woodstock, Georgia
Posts: 154
Quote:
Originally Posted by Take Vos View Post
I've made a new picture that was better calibrated.

http://www.vosgames.nl/products/Mira...ingSolved2.png

I've done some white balancing and set the black level lower (sun was shining into lens).
The white seems to be clipping a bit too much, like on bike lady's shirt. I did some color grading with your first picture, pushed it pretty far... (see attached JPG)
Attached Thumbnails
Mirage Recorder-balancingsolved.jpg  
Solomon Chase is offline   Reply With Quote
Old August 7th, 2007, 05:48 PM   #42
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Quote:
Originally Posted by Solomon Chase View Post
The white seems to be clipping a bit too much, like on bike lady's shirt. I did some color grading with your first picture, pushed it pretty far... (see attached JPG)
Yes, I noticed the ladies shirt, I was not really paying to much attention (still have to add a zebra kind of thing). But I wanted something a little bit more bright than the image you color graded.

As you noticed it had still a lot of latitude left. You may also have noticed the amount of black offset, there was quite a bit of light falling into the lens then as well, and the calibration I did was done very shoddy (The white target was not evenly lit).

The second image should already be much better, even if it is clipping a little bit to much. Although it looks to me that this camera somehow handles white clipping more gracefully as the DV cameras I am used to.

although that corner stone for that arced window, in the foreground, is not really pretty.

strange thing is that I seem to have compensated for what normally would be considered dead pixels (there are around 8 bad pixels in this image according to how the manufacturer would measure them, and really visible on an uncompensated image). I am doing statistical analysis of each pixel after compensation compared to the theoretical value and I come up with zero bad pixels for an average light intensity above 10%.
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old August 10th, 2007, 02:08 AM   #43
Regular Crew
 
Join Date: Jan 2006
Location: Woodstock, Georgia
Posts: 154
Quote:
Originally Posted by Take Vos View Post
Yes, I noticed the ladies shirt, I was not really paying to much attention (still have to add a zebra kind of thing). But I wanted something a little bit more bright than the image you color graded.

As you noticed it had still a lot of latitude left. You may also have noticed the amount of black offset, there was quite a bit of light falling into the lens then as well, and the calibration I did was done very shoddy (The white target was not evenly lit).

The second image should already be much better, even if it is clipping a little bit to much. Although it looks to me that this camera somehow handles white clipping more gracefully as the DV cameras I am used to.

although that corner stone for that arced window, in the foreground, is not really pretty.

strange thing is that I seem to have compensated for what normally would be considered dead pixels (there are around 8 bad pixels in this image according to how the manufacturer would measure them, and really visible on an uncompensated image). I am doing statistical analysis of each pixel after compensation compared to the theoretical value and I come up with zero bad pixels for an average light intensity above 10%.
Yeah, Your 2nd image (with the clipped highlights) has tons of latitude and detail in the blacks, leading me to believe that you can underexpose a good bit without worrying about noise.

I'm really interested in getting a Pike 210c, as I have some ultra fast c-mount lenses made for a 1" image sensor. (Canon f0.95, Fujinon F0.85, Schneider f0.95, and some others) Would definately give some beautiful shallow DOF shots.
Solomon Chase is offline   Reply With Quote
Old August 10th, 2007, 03:00 AM   #44
Regular Crew
 
Join Date: Jan 2006
Location: Woodstock, Georgia
Posts: 154
What is the maximum resolution you are getting right now at 14-bit, 24fps?
I read that AVT is releasing firmware with 12-bit support for pike 210c. What kind of resolution at could you get at 12-bit instead of 14-bit?
Solomon Chase is offline   Reply With Quote
Old August 10th, 2007, 03:14 AM   #45
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Hello Solomon,

I wish I had one of these fast lenses, I only have a 4.5, and I can not really use it in my room with just the lights. But it looks like the depth of field I get with this old SLR minolta lens is pretty nice.

As for the firmware, I was aware of this and I have requested it.

With 14 bits (16 bit transfer) I can do the following resolution:
1800 x 750

With 12 bits it should do:
1920 x 800 (maximum 1920 x 930)
With 12 bits and the larger Pike:
2048 x 850 (maximum 2048 x 870)

I want to get access to the light shielded columns, but for both these resolutions you would then still be able to get the full 2.40:1 ratio.
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos 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 > Special Interest Areas > Alternative Imaging Methods

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 12:09 PM.


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