Desaturate Chromatic Aberrations Alters Exposure

[johnmeyer]

I'm about to receive video from what I think was a very poor film transfer. The original is B&W, but the transfer has color rainbows that appear to be from some sort of flaw in the optics of the film transfer chain. I do not have access to the original film, so I cannot do a proper film transfer.

Here is a single frame that has been sent to me in advance of the video:

http://i177.photobucket.com/albums/w208/johnmeyer/Chromatic%20Aberration%20Restoration_zpswmrjeovp.jpg

I thought I could simply desaturate the image and get rid of the color, but as you can see from the following image, once the color is removed, it reveals that the sections that were affected by the aberration also had the luma value affected.

http://i177.photobucket.com/albums/w208/johnmeyer/Chromatic%20Aberration%20Restoration%20no%20color_zps1pisljko.jpg

It seems like there should be a simple solution to this problem, perhaps by selecting the proper color space. I guess I could also create a mask from the colors in the aberration and use those to adjust exposure of those areas.

Does anyone have some hints or ideas?

Thanks!

[Mounir]

greyscale() don't work ?

[wonkey_monkey]

Try:

converttorgb24
rgbadjust(0.3,0.59,0.11)


(untested)

[StainlessS]

Try:

converttorgb24
rgbadjust(0.3,0.59,0.11)


(untested)

+1, on something like above. Luma got affected on conversion to YUV (EDIT: YCbCr), greens appear dark, blues light (red less obvious).

EDIT: I dont get the same as your greyscale for jpg conversion to rgb.greyscale, most of the lines are missing/subdued.
Can you up a little bit of source video. (conversion to jpg seems to have changed frame)

[johnmeyer]

I appreciate all the help. I think you are right that I need to upload the video, but the disc won't arrive in the mail (it is a complete DVD) for another few days. So standby until then, and I'll cut a short section of the VOB and post it. Actually, now that I think about it, I should have waited to post that, because if color conversion is required, it will be important to start with the colorspace of the video rather than that of the still image grab.

[StainlessS]

Maybe this is cause

Imagesource("Chromatic Aberration Restoration_zpswmrjeovp.jpg").converttorgb24

#MAT="Rec601"
#MAT="Rec709"
MAT="Average"

greyscale(MAT)


Have to go out now. EDIT: Looks like 'money for old rope', you just gotta use rec601 instead of Average (ave used for jpg).

[johnmeyer]

'money for old rope'Had to ask my English wife about that one. She remembers her dad saying it all the time.

Learn something new every day.

[mandarinka]

This isn't chromatic aberration, this is rainbowing (in conjunction with some moire pattern I think). Derainbowing filters could work for the elements in chroma but don't use edge masking with them, you have the stuff in the backgrounds. I don't see how the chroma rainbows could cause the artifacts in luma though, since the original footage probably was monochrome... maybe the moire in luma was caused by the noise independently from the moire chroma?

In any case, this IMHO can't be from optical transfer, those rainbow colors would be caused by analog (electronic) video signal. And the moire probably too.

Edit: hmmm, actualy I don't know... maybe it could still be optical phenomenon.

[WorBry]

Had to ask my English wife about that one. She remembers her dad saying it all the time.


I still do.

"Good money for old rope" with emphasis on the "good money" expresses indignation at having personally been conned (duped) into paying for something of little or no value, or poor services rendered.

In this context it just means that its not giving the expected returns/quality of result.

btw, I would normally charge for this on-line translation service, but that would be "money for old rope", or summit like that :)

[StainlessS]

"money for old rope", Almost, Free money

Good "money for old rope",
"Money for nothin and the chicks are free",
(Mark Knopfler, Dire Straits, first ever MTV video, along with Sting, both from within a mile of where I come from)
(Sting, went to my school, infants/juniors/some senior, then Private [hence the lack of accent, they kick it out of you in private school]).
'lack of accent', sorry, meant much reduced, & indistinguishable.

I guess it depends upon whether you got "Good money for old rope", or paid "Good money for old rope", on your
happiness factor. :)

EDIT: Judging by his response, WorBry above, seems to be a good source of 'free money', Can anybody give me his real name, address,
TelNo and email, I have some propositions I wish to put to him.


EDIT: The chroma aberrations will still though play some part in corrupting the result, just because jpeg was screwed,
does not mean that colored bands will not cause some aberrations in non jpeg result.

[WorBry]

I guess it depends upon whether you got "Good money for old rope", or paid "Good money for old rope", on your
happiness factor. :)

Always the latter in my experience.

[geometer]

I would suggest a combined approach.

It should be possible to do an exact RGB transfer of what is there, to a professional graphics editor. Then, a WYSIWYG tool for color gamma curves etc should be used, until the luminance levels out.
Then, the result should be seen as a numeric model of the three transfer curves that together yield a balanced field, with minimal moiree. (The software should deliver the mathematical representation of what is happening by moving the sliders.)
This would further be the set of modeling values for the color conversion in AviSynth.

[StainlessS]

Always the latter in my experience.

This is looking promising :)

Can you PM me you full name, (including all details on Birth certificate), Passport number, Mortgages held, outstanding debt, all securities and hi-value properties in ownership, and anything else that you think can assist us in coming to a satisfactory outcome.

I think we can come up with some imaginative proposals. ;) (think I'm joking, see just above my Avatar and below my Usurer name)

ssS

[WorBry]

Not me mate, I know a M.F.O.R ruse when I see one.

And I know who you are. You're that geezer from Wizards of Wotsit, or whatever you call yourselves now. Saw you on Crimewatch last week; got copped flogging yellow bricks that you'd "acquired" from somewhere over the rainbow didn't yer? Serves you right. Now clear off.

[StainlessS]

Itsa fair cop guvna :)

flogging yellow brings
Should that be 'Bricks', ?, I got a whole skip load of em, limited issue and all numbered. Interested ? ($1,500 each).

EDIT: Of link below, Brilliant !!!, love it :)

[WorBry]

Yes, I was a little nervous typing when I realized who I was dealing with:

Edit: Image removed by poster.....but it was funny

Had a nose job, lost a bit of weight but oh yes, that's you alright.

@John Meyer. No need to be alarmed or confused by the dialogue. It's just an extract from a typical episode of the British soap "Eastenders" which unfortunately, or fortunately for you, is no longer broadcast in the U.S.

[Reel.Deel]

Avoid using ImageSource and other source filters (and image editors) that convert jpegs to RGB. Either use JpegSource or FFMS2 to view jpegs in their native colorspace. On a side note, when converting to RGB keep in mind that jpegs use the BT.601 colorspace with full range levels ("PC.601" (http://avisynth.nl/index.php/Convert#Options)). Also, 4:2:0 jpegs use the MPEG1 chroma placement (http://avisynth.nl/index.php/Sampling#mpeg-1_versus_mpeg-2_sampling) (MPEG2 for 4:2:2). Anyways, the luma seems unaffected by the chroma noise, if this holds true with the video, then a simple Grayscale() should suffice.

JpegSource("Chromatic Aberration Restoration_zpswmrjeovp.jpg", channel=0)

# create a lossless grayscale png of the luma channel, FlipVertical() is needed when writing grayscale pngs with ImageWriter
FlipVertical()
ImageWriter(file="c:\blah", type="png")
http://s2.postimg.org/nt5c7tpxz/jm_chroma_noise.png

[johnmeyer]

Wow, I'm in over my head here. I do need the translator.

When the video arrives in a few days and we get back to business, I'll have quite a few things to try out. Hopefully it will be easier than having to create masks and adjust exposure.

[johnmeyer]

OK, the disc arrived, and is typical when dealing with clients, they don't describe the problem correctly. I have no idea where he got the single image with the rainbows, but the actual DVD has no trace of that problem. However, it DOES have a horrible cross-hatch pattern. Since the problem is totally different than the problem I described in my original post, I am going to start another thread.

I apologize for having wasted people's time for a problem that turned out to have nothing to do with the video I actually ended up receiving.

Here is a link to that new thread:

http://forum.doom9.org/showthread.php?p=1751645#post1751645

[wonkey_monkey]

My guess about the rainbows is that the image you were sent is a photograph of a CRT screen (though I don't see any scanlines) or some weird polarization effect of photographing a flatscreen.