Matching color temperatures

[diprotic]

Hi all,
Not sure if "color temperature" is even the right term, but basically I have two cameras on one event. One came through "warm" and the other came through "cool." This is a very amateur, impromptu shoot with low quality gear--I really don't expect much, but I thought there might be an avisynth filter or something to warm up the cool roll to match the main camera. I'm not going for perfection, maybe just an adjustment to make the cuts a bit more natural.

Sample screenshots attached.

Thanks in advance!

[smrpix]

Are you intercutting these in an NLE? They all have color correction tools, and have the advantage of being able to check your corrections as you go.

Those shots each look correctable to the other.

[diprotic]

Yep, I'm using iMovie (yeah, I know). I just tried the color temperature slider. It looks like an improvement, but I've already cut it all together, and there's no way to "select all camera B" and make the same adjustment. If I make the adjustment to the source material, it will automatically apply to all camera B shots. Also, I notice there's quite a bit more contrast, not just cooler temps. Hoping to soften the contrast and warm the colors in one pass, if at all possible.

[budwzr]

Match the blackest black, then the whitest white, and you're color matched. For color correction (grading), use an "S" curve in the "RGB Levels" tool to avoid clipping the whites/blacks.

[diprotic]

Match the blackest black, then the whitest white, and you're color matched. For color correction (grading), use an "S" curve in the "RGB Levels" tool to avoid clipping the whites/blacks.

I'm afraid I don't know what you mean by all that. I think I want both color correction and color matching, but I'm not sure how to do that with avisynth or similar. Ideally the solution will allow me to run a batch job on all my sources, outputting to similar 720p mp4.

Thanks again.

[diprotic]

I think I found what I'm looking for in avisynth's tweak() filter. I pulled the contrast and bumped the brightness and the image isn't nearly as harsh. I imagine I could tweak the hue to get a warmer picture.

But, I've only ever used avisynth with HCenc, which is an MPEG2 encoder. I'd like to output my sources back to native 720p h.264 mp4 (I know this will require a reencode and I will necessarily lose some infinitesimal amount of quality). Which encoder is up to the task?

[manono]

Which encoder is up to the task?

Any one which accepts AviSynth scripts as input. XviD4PSP is one such. Or you can open the script and make a lossless AVI in VDub and then open that in whatever encoder you want, just about.

[jagabo]

You could try using the ColorLike() filter in AviSynth. The "cold" image warmed up with ColorLike():



It will probably work better with the source videos, and it needs further adjustments, but it's much closer.

warm=ImageSource("warm.png").BilinearResize(720,360).ConvertToYV12()
cold=ImageSource("cold.png").BilinearResize(720,360).ConvertToYV12()

#part 1, build histograms
#warm.WriteHistogram("warm.txt", 1)
#cold.WriteHistogram("cold.txt", 1)
#Interleave(warm,cold)

#part 2, make cold look like warm
Interleave(warm,cold.colourlike("cold.txt", "warm.txt"))

[diprotic]

You could try using the ColorLike() filter in AviSynth. The "cold" image warmed up with ColorLike():


[Attachment 20933 - Click to enlarge]

It will probably work better with the source videos, and it needs further adjustments, but it's much closer.

warm=ImageSource("warm.png").BilinearResize(720,360).ConvertToYV12()
cold=ImageSource("cold.png").BilinearResize(720,360).ConvertToYV12()

#part 1, build histograms
#warm.WriteHistogram("warm.txt", 1)
#cold.WriteHistogram("cold.txt", 1)
#Interleave(warm,cold)

#part 2, make cold look like warm
Interleave(warm,cold.colourlike("cold.txt", "warm.txt"))

Wow, that looks really good. I think the colors are just right. Maybe just a touch of contrast and it's definitely good enough for this project. Thanks a lot!

[diprotic]

I have one other thought: Since I've already cut and rendered the sequence and I really don't want to deal with intermediary files, is there a way I can create histograms from the warm footage, then pass the whole edited warm & cool sequence through it? Ideally the warm shots will remain unchanged while the cool shots will get the necessary warmth. Possible?

Edit: I'm not looking for cinema-quality grading, I just want to make the cuts between cams a bit more natural.

Thanks again!

[smrpix]

is there a way I can create histograms from the warm footage, then pass the whole edited warm & cool sequence through it? Ideally the warm shots will remain unchanged while the cool shots will get the necessary warmth. Possible?

Yes and no.

Go back to your imovie sequence and make the color corrections in imovie to one of the "bad" clips. imovie has similar color functions to avisynth except that you can use sliders and see what you're doing. You can then copy and paste this correction to the rest of the "bad" clips. It really shouldn't take very long, even if you've got dozens of clips.

[diprotic]

is there a way I can create histograms from the warm footage, then pass the whole edited warm & cool sequence through it? Ideally the warm shots will remain unchanged while the cool shots will get the necessary warmth. Possible?

Yes and no.

Go back to your imovie sequence and make the color corrections in imovie to one of the "bad" clips. imovie has similar color functions to avisynth except that you can use sliders and see what you're doing. You can then copy and paste this correction to the rest of the "bad" clips. It really shouldn't take very long, even if you've got dozens of clips.

Hmm. yeah, that is the other way to go. I didn't notice the ability to copy/paste attributes, that is much better than "eyeballing" each clip. Still, iMovie didn't match as well as colourlike(), so if I can pass the rendered clip through that without too much trouble, I may go that route.

[jagabo]

I have one other thought: Since I've already cut and rendered the sequence and I really don't want to deal with intermediary files, is there a way I can create histograms from the warm footage, then pass the whole edited warm & cool sequence through it? Ideally the warm shots will remain unchanged while the cool shots will get the necessary warmth. Possible?

Not really. You could use Trim() commands to break out all the cool sections, adjust them, then patch everything together again. But if you use transitions where both videos are visible at the same time (crossfades, wipes, etc.) there will be abrupt color changes.

Can you adjust the cool clips then import them into iMovie replacing the original cool clips?

[diprotic]

Can you adjust the cool clips then import them into iMovie replacing the original cool clips?

That's definitely the right way to go. I'm pretty sure that would work, but I got a bit stuck in the process.

I haven't used VirtualDub in more than a decade. I produced good looking samples, but uncompressed 20s sequence cost 500MB disk space.

What do you suggest as a way to go from the original mp4 to a reasonably compressed, color-corrected substitute? It's OK if I lose some quality, in this case the qualitative difference will be minimal compared to proper colors.

[jagabo]

What do you suggest as a way to go from the original mp4 to a reasonably compressed, color-corrected substitute?

You're going to need a codec that's available for both platforms. Can you use HuffYUV on the Mac? MJPEG? Short GOP MPEG or AVC?

[budwzr]

I'm getting this from Sony VegasPro "Color Match" filter. Still needs saturation adjust and WB adjust.



Then WB and Saturation:



Conclusion: There's too much mismatch between these images. It's like an innertube, if you step down on one point it expands somewhere else. I don't think there's gonna be a batch solution. Probably have to go one by one by hand and eye.

[smrpix]

If you do want to try the copy and paste attributes route (rather than the cut and paste clip route) simple gamma adjustments in the RGB, Red, and Blue channels will give you a matching image. Here is an example from Premiere, but using only simple level controls such as those available in iMovie. (You may even be able to simply copy the numbers)

[jagabo]

If you do want to try the copy and paste attributes route (rather than the cut and paste clip route) simple gamma adjustments in the RGB, Red, and Blue channels will give you a matching image. Here is an example from Premiere

That looks pretty good. Close equivalents in AviSynth:

ConvertToRGB()
RGBAdjust(rg=1.18, bg=0.59)
Levels(0,1.53,255,16,255)

Adjusting the levels before conversion to RGB may keep the blacks from getting crushed. Or use ConvertToRGB(matrix="PC.709") to avoid the contrast stretch, then adjust gamma and levels accordingly.

And one last note, the bright sky in the cold picture is causing the rest of the image to be darker. So you may not need as much luma gamma adjustment in other shots.

[budwzr]

Hey, how about you people show a before and after to help us dummies follow along? (Fer Krisakes)

That Premiere is ridiculous with all those boxes within boxes. Geez, that's confusing. I can't even tell what's what. In Vegas, all that is represented in one simple view with interactive curves.

Aint Dat A Peach?

[jagabo]

Hey, how about you people show a before and after to help us dummies follow along? (Fer Krisakes)

The OP posted the before images in the first post.

[budwzr]

Hey, how about you people show a before and after to help us dummies follow along? (Fer Krisakes)

The OP posted the before images in the first post.

Yeah, but then we have to flip back and forth.

[smrpix]

That Premiere is ridiculous with all those boxes within boxes. Geez, that's confusing. I can't even tell what's what.

The multiple boxes are a) a composite image, you can actually only display one at a time and b) they don't need to be revealed at all except c) they ROUGHLY replicate what you see in iMovie.

Compositing it this way (I felt) made it easier to understand the parameters.

Like you, I prefer curves, but I don't believe they are available in iMovie's color corrector.

iMovie color corrector:



My first go round (too complex):

[diprotic]

Wow, thanks all. I see some really good results, certainly good enough for my little dinky project.

Here's where I stand:

I can go about this two ways. I can either adjust the colors directly in iMovie, or run the camera B's roll (the "cool" footage) through some Avisynth goodness.

Other NLEs are out of the question, as I have already cut the sequence in iMovie, and I don't have budget for a replacement.

The latest iMovie (IIRC 10.0) has very simple color correction options. I may have missed the advanced options, but I didn't see per-channel adjustments (just brightness, saturation and color temperature)

Avisynth is looking like a good option, thanks to jagabo for some script suggestions. I'm still not 100% on how best to produce the "warmed up" clip.

Jagabo asked

Can you use HuffYUV on the Mac? MJPEG? Short GOP MPEG or AVC?

Short answer: I don't know.

Long answer: I cut the sequence in iMovie 10.0 on OSX Mavericks. I have an XP VM for anything Windows (avisynth, etc.) I have no problem coming up with whatever environment works best, though. I'm looking for the most straightforward way to go from the cool source, through avisynth adjustments, to a warmer replacement for camera B that I can load back into iMovie. Ideally avisynth's output would be h.264 mp4, so there is as little difference as possible from iMovie's perspective. Some recompression loss is acceptable; I'm not going for perfection.

[budwzr]

OK, yeah, that's much better. I like this layout.

Hey, SMR, does Premier have a slice tool. Like you make a straight line somewhere and it shows you the RGB distribution.

[budwzr]

Ideally avisynth's output would be h.264 mp4, so there is as little difference as possible from iMovie's perspective. Some recompression loss is acceptable; I'm not going for perfection.

That "solution" might be doable, but you'd need to be an expert in scripting, and know all the ins and outs. Jababo is an expert in that stuff and makes it look easy, but it's not. Especially hard for a Mac-type person, no offense. There's a lot of nesting, and math, and it just gets really ugly fast.

That's why you're still stuck right now. You're better off just to get an NLE.

This is the "S" curve, with high blacks and whites protected, I referred to earlier. I have no clue how something like this could be explained as a script, but I can see right away what Smr is doing in Premiere. Just at a glance. He's got it dialed in real nice. In the master, he has the blacks and whites protected too.

[diprotic]

Ideally avisynth's output would be h.264 mp4, so there is as little difference as possible from iMovie's perspective. Some recompression loss is acceptable; I'm not going for perfection.

Especially hard for a Mac-type person, no offense. There's a lot of nesting, and math, and it just gets really ugly fast.

That's why you're still stuck right now. You're better off just to get an NLE.

Seriously? You're inferring that I have a low technical aptitude from the platform I happen to be running for this particular job? Take a look at some of my past posts. Many involve complex ffmpeg/mencoder invocations, sometimes scripted in bash, on platforms like Arch Linux. No, that doesn't make me a restoration master like jagabo, but I'm not some clueless fanboy.

And no, that's not why I'm stuck right now. I have everything I need to do the actual color correction (thanks again to jagabo). All I'm looking for is a workflow to apply that to camera B's roll in the most efficient way possible. I could absolutely figure this out on my own, but it seems there are some pretty knowledgeable and helpful folks here who could save me the time.

[poisondeathray]

So are you stuck on that last step ? how to go from .avs script to MOV intermediate for imovie ?

You can encode .avs scripts with ffmpeg for example . imovie is picky in what it will accept . Commonly used lossless formats would be quicktime animation (RGB/A) , png in mov (RGB/A) , or mjpeg, or prores (I can't recall if imovie will accept prores, definitely FCP / FCPX)

mjpeg will probably be the most compatible format if you don't need lossless

e.g . -q:v is the quality or quantizer scale, lower produces better quality, larger filesizes

ffmpeg -i input.avs -vcodec mjpeg -q:v 4 -acodec copy output.mov

If you have many to process, you can use a batch script . There are avisynth batch scripter tools as well

[budwzr]

Seriously? You're inferring that I have a low technical aptitude from the platform I happen to be running for this particular job?

Because you don't ask the right questions. Pass images through a histogram? That's typical of a Mac user, they want a preset magic wand solution for everything. I wish I could pass my image through a Brad Pitt filter too. Hahaha

[smrpix]

OK, yeah, that's much better. I like this layout.

Hey, SMR, does Premier have a slice tool. Like you make a straight line somewhere and it shows you the RGB distribution.

Just so we're on the same page, you do know the second layout is Avid, right? I like it better too.

I've never seen that slice tool in Premiere (or Avid for that matter.) I believe I've only seen it as a built-in function of a standalone tectronix. Don't know about Vegas in that regard, either.

[diprotic]

Just did some tweaking. I tried colourlike() and rgbadjust(). I ended up on colourlike() with a bit of tweaking (sat=0.9,bright=10). It's not perfect but much better than the abrupt warm/cool contrast of before. I'm running the batch jobs tonight, will post results. Thanks again!