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10th June 2018, 07:15 | #61 | Link | |
Acid fr0g
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To tell you an example, there is a very large (more than 100 square meters) sponge in Dahab blue hole that is completely green and you can see with your bare eyes but not with any cam I have seen so far. I keep on thinking that the simplest yet complex task would be to associate depth to color correction, feeding diving log. This could be the first step. Today I will have a dive on a wreck and probably I will use natural light outside and artificial light inside. I have exchanged the torchlight head from a narrow beam to a 120° beam and set the cam accordingly to same lens width (it merely use a portion of 4k sensor and gives 1080p output, I think). I changed the camera too for a 4k, mostly to have much better EIS and better light (sony sensor). It's still on the cheap wagon (Apeman A80) but has a diving mode too. Nothing special: it simply gives an automatic but fixed red filtering. Obviously I will use it outside and disable it when using artificial light. I won't for this dive, to give you an idea of water absorbtion. It will be a moderately deep one (40 meters) but red will be gone to hell already. I will see if there will be some footage worth of posting. Any preferred file hosting? Perhaps youtube is the best place, despite moderate quality corruption. Edit: no wreck footage. F***ing camera body collapsed under pressure at a ridicolous 32m over a 40m certified depth. No water leakage but buttons were not operative.
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@turment on Telegram Last edited by tormento; 11th June 2018 at 10:30. Reason: Utter jinx. |
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10th June 2018, 08:41 | #62 | Link | |||
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Like I said, I was only interested in seeing how these correction methods hold up in varied scenarios. Purely that. I hope it won't be taken that this will lead to something. No preferred file host for me, as long as its safe.
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Nostalgia's not what it used to be |
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10th June 2018, 10:01 | #64 | Link |
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Nuther daft question, is there any benefit to taking your own red light source, ie red floodlight [EDIT: with some kind of diffusion to avoid bright spots] to bolster the remaining natural reds (rather than filtering).
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I sometimes post sober. StainlessS@MediaFire ::: AND/OR ::: StainlessS@SendSpace "Some infinities are bigger than other infinities", but how many of them are infinitely bigger ??? Last edited by StainlessS; 10th June 2018 at 10:05. |
10th June 2018, 14:37 | #65 | Link | |
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My adventures are mostly freediving madness Not sure my samples qualify as representative. Often there is "sky" which I currently have no way to protect (tends to become red). Here are some directly cut from original: https://drive.google.com/open?id=1HB...NKh2YUwwAY86Kn triggerfish: good colors GOPR0201.MP4: needs dynamic treatment turtle: I fail to get any color out of it
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10th June 2018, 15:34 | #66 | Link |
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Finally sense prevails. Resolve has a Color Match function for use with SpyderCheckr and X-Rite color checker boards, btw. Downside of course being that you need to include reference shots with each change in scene. Even a white balance (grey) card frequently in shot would be helpful in establishing neutral balance in post. In that clip Tormento posted I was able to use the white stripes on the fish as reference. In the other samples from that YT GoPro video I had to use what I could- a shell, whitish coral on rocks, a fish that I thought was maybe cool-greyish - and as a last resort, highlights in rising air bubbles from divers regulators, where not totally blown-out.
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Nostalgia's not what it used to be Last edited by WorBry; 10th June 2018 at 21:28. |
10th June 2018, 15:43 | #67 | Link | |
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Thanks Shekh - good test material indeed. Edit: What turtle species is that btw, just to know what colors I might hope to get from it ?
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Nostalgia's not what it used to be Last edited by WorBry; 10th June 2018 at 21:17. |
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11th June 2018, 15:51 | #69 | Link |
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Well if its Red that is mostly missing, probably wrong though. (maybe, pinkish then ???, [EDIT: or orangy fleshy])
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I sometimes post sober. StainlessS@MediaFire ::: AND/OR ::: StainlessS@SendSpace "Some infinities are bigger than other infinities", but how many of them are infinitely bigger ??? Last edited by StainlessS; 12th June 2018 at 00:56. |
11th June 2018, 22:23 | #70 | Link | |
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Nostalgia's not what it used to be Last edited by WorBry; 11th June 2018 at 22:28. |
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12th June 2018, 02:15 | #71 | Link | |
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Is this about right for the color of the turtle ? Original: Corrected Resolve: This was using Channel Mixer and Color Temp/Tint only for color balance. Plus some levels adjustment, contrast, mid-tone detail (local contrast) and a teeny pinch of sharpening to tease out the turtle detail as best. Obviously no denoising. As you can see there's this red coloration thing going on the left of image - the light bouncing off red coral? I can reduce that with a qualifier but it will also remove some markings on the turtle that have a similar tones and I'm not sure if that is how they are supposed to appear. If it looks about right I'll try it with VDub2.
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Nostalgia's not what it used to be Last edited by WorBry; 12th June 2018 at 04:45. |
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12th June 2018, 02:23 | #72 | Link |
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Images of turtles, (Amongst them some tortoises and terrapins):- https://www.google.com/search?q=turt...w=1280&bih=874
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I sometimes post sober. StainlessS@MediaFire ::: AND/OR ::: StainlessS@SendSpace "Some infinities are bigger than other infinities", but how many of them are infinitely bigger ??? |
12th June 2018, 10:22 | #73 | Link |
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Looks like there is still a lot of residual tint, but can it be adjusted further without ruining everything else?
Green sea turtle from red sea. I added another sample close to surface (2..3m) Hard to say what forms the red stripes. It definitely belongs to landscape, not a lens flare. There is same effect on the bottom sand where lighting transitions to shadow. I'm quite sure the sand is uniform. So I think it becomes red because of flaws in out correction method (I get the same with 6-axis color correction).
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12th June 2018, 13:28 | #74 | Link |
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Thanks. I can probably tweak it some more with the Color Wheels to address the residual aquamarine tint, which of course impacts the turtle coloration as well. That's why I was querying the turtle species and expected coloration - although termed 'Green Turtle' the shell coloration is typically more brownish. I could also apply a secondary qualifier to diminish/offset that rust coloration on the rocks and the shadow cast on the sand, but it will be difficult to do so without impacting the warmer colors on the turtle in some way - difficult to isolate the turtle with a shaped mask ('Power Window' in Resolve speak) as it's passing in front of those rocks without tracked rotoscoping. Might have to strike some kind of compromise. I also got a similar outcome with VDub2, applying the same Channel Mixer biases and adjusting with the '6-axis corrector' but I didn't spend much time on it. If I can get a better result tweaking the balance in Resolve, I'll have another go at it. Only had time for a brief look at the other clips. A couple are pretty straightforward (the 'Snapper Fish' ones) but the others are definitely challenging - might have to get creative with those strong 'skylights' streaming in.
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Nostalgia's not what it used to be Last edited by WorBry; 12th June 2018 at 14:28. |
13th June 2018, 11:58 | #75 | Link |
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I thought some false coloring pops because I'm mixing srgb values.
This is result of correction after applying srgb to linear filter: Almost grey, but at least no red spots.
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13th June 2018, 16:12 | #76 | Link | ||
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Interesting.
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Meanwhile.....here's the best compromise I could come up with in Resolve. Any warmer than that and the rust coloration on the rock just bloomed. It proved impossible to a apply a qualifier to diminish/offset that and the shadow cast on the sand. There was just too much overlap in the wide spectrum of hues with those on the turtles shell. To try and do so just wrecked the detail on the turtle that I'd worked hard to bring out. No amount of feathering (smoothing) of the qualifier helped and blurring...well just blurred it. Best I could do was to target a narrower range of 'hot-spot' hues picked off the turtle shell (using the Hue-Saturation Curve) and partially desaturate them, which helped a bit. Edit: The image as posted definitely shows more residual green tint (notably on the seabed) than the original graded image. Not sure why, but I aint redoing it. And then another go at it with VDub2 applying similar Channel Mixer biases and just a little tweaking with the 6-axis correction filter. Increasing the pixel radius a tad (1.6) in the Unsharp Mask brought out a bit more detail on the turtle. Bear in mind that there was no neutral reference to go by in this clip so I had to base it on a best judgement of the coloration of the turtle shell from the image you posted. Too warm maybe? No residual green tint there though. I guess this a prime example of the question StainlessS posed earlier: Quote:
That (I would suggest) is the reason why underwater photographers/videographers favour using white (daylight balanced, one assumes) light sources for illuminating sea-life at close range: When corrected it brings out the 'truer colors' of the subject whilst leaving the background tinted, lending itself to vivid images like: https://d1rirzyrd4ly69.cloudfront.ne...5023_62594.jpg A pink (magenta) tinted light source would (after correction) turn a blue tinted background more green.....I think. Does the turtle care ? http://birdsasart.com/248/Pacifc-Gre...-Galapagos.jpg Evidently not.
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Nostalgia's not what it used to be Last edited by WorBry; 13th June 2018 at 18:57. |
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13th June 2018, 17:41 | #77 | Link |
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Internal filter "gamma correct" is doing srgb to linear or reverse conversion. It works with rgb64, and 6-axis correction too (but I just discovered there is color error in x64 build, so if you try it make sure to use x86 version).
convert format to 16-bit yuv (needed to avoid some banding) convert format to rgb64 gamma correct ... full project (should work if you save it in same folder where mp4 is). https://gist.github.com/shekh/3b3a97...1170-vdproject
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13th June 2018, 20:05 | #78 | Link |
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OK thanks. So the sRGB to linear gamma thing is effecting a significant shift to blue and you are then using the Red-Green and Yellow-Blue sliders offset to bring back the warmth. Have to experiment with that approach.
I see you set Unsharp Mask to serveas a 'local contrast' enhancer, with the pixel radius up at 25. Thought about that but wasn't keen on the stronger banding that was coming through. Here 0.85 strength: Also didn't denoise in the above grade and I think this clip would benefit from it; so here pre-denoised: Code:
SMDegrain(tr=2, thSAD=400, truemotion=false, contrasharp=true)
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Nostalgia's not what it used to be Last edited by WorBry; 13th June 2018 at 21:38. |
14th June 2018, 17:50 | #79 | Link |
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Had another go at it with Resolve:
Tried turning the turtle shell colors a bit browner, but then the rust tint starts to come through more in the shadow from the rocks: So there is a trade-off. Maybe needs brightening a tad, but in terms of color balance, better results all around. What's more, all done with the Channel Mixer - no secondary tweaking with Color Temp/Tint, the Color Wheels or qualifiers. After tuning the sub-channel biases some more just needed finer balancing of the primary R,G,B channels. Then levels, contrast and mid-tone detail and partial desaturation of the shadows. Also used the denoised (SMDegrain) clip as source here. With that realization, I'm more confident about achieving a similar result with the Channel Mixer in AVISynth.
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Nostalgia's not what it used to be Last edited by WorBry; 14th June 2018 at 18:08. |
14th June 2018, 19:32 | #80 | Link |
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Adjusted for better looking blue, added sharpening and denoising.
I thought the gamma correct approach to defeat mid-shadow colorization is universal "do not mix srgb values linearly" but I cannot confirm this with simple pattern. Don't know why it really works here. this turtle had enough torture, let it go?
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