Mirage Recorder

[John Papadopoulos]

Black level and contrast will boost the sense of saturation, just like with analog imaging systems. That's why this looks more saturated:

http://img265.imageshack.us/img265/9...hed1coplo0.jpg

I would set the CRT black by eye. The proper setting depends on room lighting, reflectance of surface and many other parameters. I wouldn't trust anything except the eye for this.

[Take Vos]

black level, yes you do that by eye, greyscale tracking should only be done using instruments.

[Take Vos]

Hi, so I've been working on calculating the color matrix from a picture of a ColorChecker.

Here is the result:
http://www.vosgames.nl/images/Mirage...cal_bp_col.png

[Take Vos]

I actually thought when I first saw the picture that it was too much, but then I actually looked at the ColorChecker under light and compared it to the screen and it is really close.

I guess you get used to the desaturated look after working on something a long while.

Now of course I also need to look at some real live pictures before I can truly say the picture is correct.

Cheers,
Take

[Take Vos]

So, I have shot some footage of the park from my window, to see how everything will hold up in real live.

I dropped it in Final Cut Pro and started editing it. I happy to say that FCP will run the timeline (edited footage) in real time when the image is zoomed to 50% or smaller, at 100% it will skip frames but still work pretty good. The footage is on the harddisk that I've recorded on, a single SATA western digital SA16 250 GB disk.

Because this is a third party codec it does not do real time rendering of things like transitions, but scrubbing through a transitions works pretty smooth.

In any case I am currently exporting the edit to my intermediate codec (so it renders in high quality). It says it needs two hours to render 1 minute and 35 seconds (I will need to solve some performance issues :-). I actually thought that FCP would render on both cores of my computer, but only 50% cpu time is used.

In any case I will try and put the footage online for all to see, does anyone have a preference for which codec I should use to export it? I thought I would use Apple's codec that they also use to encode their movie trailers in.

[John Papadopoulos]

So it's 75:1 real time. What cpu is on your laptop? Any multithreading?

The noise looks very nice on the last sample.

I think the look is more important than precision. We know it's uncompressed video. WMV or MOV is ok.

Don't get the desaturated look syndrome:)

[Take Vos]

Hi there, it took a little longer because there was a bug in my codec stopping the last conversion. I didn't know about a certain data transfer method.

First I would like to apologise for the shaky image, I have no tripod mount made for my camera and was a bit excited being it my first real footage.

Anyhow, I finally made a conversion to h.264, which is the codec that Apple really likes. I did notice that when the image is particularly smooth and out of focus it tents to color band quite a bit, therefor I also added some still images to show the difference.

This was the workflow:
- Create calibration data for camera using DNFCalibrator (DNF stands for Digital Negative Format)
- Capture footage with Boom Recorder
- Drop footage on the Final Cut Pro timeline and edit (the timeline automatically reconfigures to the DNF Intermediate codec)
- Export footage as QuickTime with the DNF Intermediate codec
- Using the Compressor.app (Apple) convert the DNF codec to h.264 codec

You may want to right click and "save as" for the movie file, otherwise it will show inside the browser.

http://www.xs4all.nl/~takev/ThePark-H.264.mov
http://www.xs4all.nl/~takev/TheParkImage1.png
http://www.xs4all.nl/~takev/TheParkImage2.png
http://www.xs4all.nl/~takev/TheParkImage3.png

[Take Vos]

So, this footage was made with a CF16HA1 (16mm) which has a 43 degrees horizontal viewing angle. Which I think is a normal lens for this camera.
If I would add two other lenses, which should I order.

These lenses are available, third number is the 35 mm equivalent:
12.5 mm, 54 degrees, 35 mm
16 mm, 43 degrees, 45 mm
25 mm, 28 degrees, 70 mm
35 mm, 20 degrees, 100 mm
50 mm, 14 degrees, 140 mm
75 mm, 9 degrees, 200 mm

[Paul Curtis]

Take, congratulations, you're doing an amazing job! It's great to watch your progress.

The png show a lot of pixelation, is this a product of the de-bayering? There's some FPN too, is that right? If you look at the tree going across the yellow advertising there's a white outline in the blue channel. Im trying to work out whether this is a debayering artifact or whether it's the lens. (You can see chromatic aberations quite clearly, which has to be the lens - check the roof of the mini).

I would love to see some bright sunny sky and darker areas together sometime.

So the lens isn't so hot, i wonder what other choices there are for this sensor size? This is the fujinon right? This has been a concern for me and this particular sensor - getting a good lens on there. (unless of course the aberations are correctable?)

It also looks like you're shooting through a window as well? That can't be helping at all!

Does the camera has an OLPF? Im not sure it does, do you think this will become a problem when the camera is moving a lot?

The colours look very good and the range seems pretty good too. Very promising!

I'd like to see a wide lens the 12.5 because wide is more difficult than zoom. on 16mm a 40mm is usually the 'normal' lens so you're pretty much there already.

So when's the windows version come out ;)

cheers
paul

[Take Vos]

Thanks paul,

The pixelation is I think indeed from the debayer, maybe I should teach it how to do diagonal interpolation. Right now it seems to think, "this is neither horizontal nor vertical lets use the box interpolator".

I am thinking of an new design for a debayer, but it probably won't work, I would use a median filter because as they say, "median filters are edge preserving", I just have to see how true that is for demosaicing a bayer.

There is quite a lot of color aberation, it seems to be caused by the lens. I first thought it was my debayer algorithm, but the color shift was extending beyond the edges. Also in the video you can see the color aberation on a tree, the color shift swaps around when the tree is panned from the left to the right side of the sensor/lens.

Yes, I was shooting through the window, it is cold outside.

There is no OLPF, and as you see I am moving the camera a lot. I think the motion blur takes care of the aliasing. I am not sure what happens when I reduce the shutter time, I guess I will have to try.

There won't be a windows version, until Microsoft decides to implement a lot of APIs from Apple. It may be possible that at some point the QuickTime component will work on windows, so that at least it becomes possible to edit on windows.

[Take Vos]

Can you fix chromatic aberrations, by just looking at the distance from the center of the screen and shift red and blue back?

[Paul Curtis]

Originally Posted by Take Vos

Can you fix chromatic aberrations, by just looking at the distance from the center of the screen and shift red and blue back?

Sometimes, it depends on the lens and the type of abberation. the magenta/green type you're seeing changes depending on the contrast, so the top of the mini would show more. You can also on the tree trunk that when the lighter path behind crosses they are more obvious there. So it couldn't be a global shift. Point it through a tree at the sky, that'll show up the worst.

Is that fujinon designed for a single sensor or designed for a 3 CCD sensor? Do you have anything else to compare with?

http://www.vanwalree.com/optics.html is a nice reference.

A camera like the EX has CA correction built in (so it must be algorithmically possible for a given lens). You can see when zooming the lens that the aberations appear then disappear when you stop.

Shooting through the window really isn't helping your contrast in the scene.

The OLPF effect will most likely show more for textured materials when you're moving slowly around with a higher shutter speed. I suspect it might end up being an issue. Just slowly move the camera pointing at some patterned material perhaps and create a small region of interest uncompressed movie from it.

Have you seen any heat or thermal issues with the Pike?

Why did you choose the Pike in the end, did you look at some others first?

cheers
paul

[Take Vos]

Hello Paul,

I saw an article about fixing chromatic aberrations. It seems that is basically scales the color channels. You have to specify the amount on a per lens basis, so it will probably be a Final Cut Pro filter.

From what I understand de fujinon is a single CCD lens. I have an old Minolta 35mm reflex camera lens.

The Pike can become quite hot, I am planning to make a cooling system.

I have chosen the Pike because it was pretty much the only one that handles 1920x800 at high bit depth at 24 fps and IIDC that could be connected to an Apple and had drivers for it.

[Paul Curtis]

[QUOTE=Take Vos;815316]Hello Paul,
From what I understand de fujinon is a single CCD lens. I have an old Minolta 35mm reflex camera lens.
QUOTE]

I don't know ultimately what you intend to do with your system, but if you're hoping to use it out there in the field then the lenses are going to be key.

Ive been looking for suitable lens options for this sensor. It's between 2/3 and 35mm and there's quite a gap here. Some S16 lens *may* be big enough but for the most part the imaging circle will be too small as this sensor is bigger than S16. (it's also difficult to get technical details on a lot of older lenses)

You can stick 35mm on with a crop factor, around 2.5 i think. So a good 14mm lens works out to around 35mm fov, but the fastest i've found is f2.8 which'd be like having the DOF at f7 on 35. I think the better 35mm lenses would be fine resolution wise even though you're only using the centre.

There're a few lenses specifically for APS-C sized sensors, i have a canon 10-22 which is actually a pretty nice lens. But it's not manual so unless you have a birger mount it's not going to work. I don't know if there are any manual lenses for APS-C but they would be an interesting option because they're designed for the smaller sensor size and they'd be plenty big enough for this sensor. 10mm would be a nice wide fov on it. Again these tend not to be very fast.

So machine vision lenses are the most obvious choice. The fujinons look nice on paper but so far aren't performing too well in real world. Do you know what aperture you had that on - probably smaller than f1.4 i'd guess? The Pentax are probably at the same level and the scheider kreuznach are a lot more expensive, perhaps they'll perform better?

A lot of SLR lenses don't have much travel on the barrels for focus, i'm not sure about all the machine vision lenses.

So unless im missing something blindingly obvious (not the first time!), i think it might be a struggle to get some quality glass in front of the sensor to operate at reasonable fov at a flexible range of Dof for narrative purposes.

Conversely i don't think there's a suitable 1920x1080 CCD sensor in 2/3rds format -- which'd open up the choices enormously.

cheers
paul

[Take Vos]

Hello Paul,

All the 2/3 lenses I've seen are designed for 3CCD, not for a single sensor. 35mm SLR is interesting, especially if you need a long lens, but it is almost impossible to get really short 35 mm SLR lenses.
S16 lenses would also be interesting if we can find a couple that produce a 1" circle (altough at 2.40:1 ratio the circle may be slightly smaller).

Machine vision lenses remains the only solution if you want to buy them new. The Fujinon are not that expensive 250 USD per lens, the number of blades in the aperture is pretty good and the build seems very solid. The focus travel is pretty short but smooth, aperture setting is also smooth with a light click at each stop. I think you can find a follow focus that is geared for these short travel lenses.

I switched aperture quite a lot in the movie, it was quite dark outside, so I had it open pretty wide. I also wasn't that careful is focus.