Help with color correction - VHS Source

[JayD]

I'm trying to bring out the color in this VHS capture. The guys pants in the video are supposed to be red, but have a pink-ish tone. Experimenting with Tweak and ColorMill the skin tone ends up looking like an Oompa-Loompa. I've attached a 30 second sample clip. If someone could offer some help I would appreciate it. Thanks.

[raffriff42]

Gotta be careful trying to restore bright reds off a VHS because of the noise, but you might try this:

M=MaskHS(startHue=75, endHue=115)
\ .Invert
\ .Blur(0.4)
\ .BilinearResize(Width, Height)
\ .ColorYUV(levels="TV->PC")
Overlay(Tweak(sat=1.3, hue=(-15)), mask=M) ## pants only, more or less
Tweak(sat=2.0) ## overall

before...

[Attachment 43692 - Click to enlarge]

after...

[Attachment 43691 - Click to enlarge]

[LMotlow]

An RGB vectorscope from frame 393 shows poor color density. Colors contract toward the center of the center of the graph, which indicates gray -- literally, color is grayed-out.


Most of the sample has suppressed brights, black level too high, color undersaturated, blue response is non-linear (suppressed at the top, too bright across mids and bottom). In RGB use gradation curves to make a slight S-shape contrast curve for blue, and same for overall RGB levels. Use ColorMill to raise the midtone levels and reduce the lower midtones (ColorMill's "Middle Point" sliders), use ColorMill for overall saturation increase and to very slightly redden overall hue (no more than about 5% or your grass and trees will turn gray). I used Vdub's Hue-Saturation-Intensity filter to very slightly increase red-only saturation (about 5 to 10%). Leave green alone. Check your levels with a histogram or pixel reader when pumping up the brights and midtones, or you'll blow the hell out of your highlights.

original frame 393:


after gradation curves, ColorMill, Hue-Sat_Intensity filter:


This fix won't work for the middle shot (closeup of reel action), which would be too contrasty, over saturated, too dark, and too red. Does this mean that you often have to use different corrections for different shots? Yes, indeed. Welcome to VHS.

The VirtualDub filters and settings used can be loaded by opening the attached .vcf file in Virtualdub ("File" -> "Load processing settings..."). You must have all 3 mentioned VDub filters in your plugins folder..

[johnmeyer]

You might take a look at "GamMac," something that StainlessS developed over at doom9.org. It was designed to help VideoFred with his film restoration work, and was primarily designed to automatically correct the gamma. However, it also can do some remarkable restoration with colors. Since your sample does have both problems, it looks like it might be a good match to your problem.

GamMac

Colormill can produce some amazing results, as you just saw, but you'll probably have to adjust the settings scene-by-scene. I just got finished with a two-hour (one tape) VHS restoration, with lots of scenes that were shot without doing a white balance (1980s camera that only had manual white balance). I had to do corrections scene-by-scene. I did the work in my NLE, Vegas Pro.

One problem if you have to shift the colors, rather than just change saturation and gamma (not your problem with the one scene shown), is that you almost never can get good results by simply shifting them all back to the same place. For instance, I did a correction on one scene, shot outdoors, where everything had a blue-purple cast. I found neutral colors in the shadows, midtones, and highlights, and used Vegas to sample those neutral areas and then used a color wheel to apply the exact opposite color to achieve neutral. This is similar to what you can do in Colormill. Everything looked much better, but certain objects ended up with really weird colors. For instance, a white horse suddenly became purple!

I was able to sample and track that purple horse color and then reduce it, first by applying the opposite color and then desaturating. It worked great, but was a lot of work. I should have tried GamMac, but forgot about it until after the job was finished.

[jda]

(found my old password for my old login)
I ended up using a different clip that was easier to work with (for me) as a starting point and make adjustments for the different scenes.

Before:

[Attachment 43702 - Click to enlarge]

After:

[Attachment 43703 - Click to enlarge]

[johnmeyer]

What software did you use to make the improvement?

[jda]

What software did you use to make the improvement?

Color Mill and Tweak.

[raffriff42]

...and your script plz?

[johnmeyer]

If he's using Colormill, that's a VirtualDub pluin, so no script.

[edit]although I guess he could be calling Colormill from within an AVISynth script ...

[jda]

...and your script plz?

I'm trying to duplicate it now. I was playing around with MeGUI and somehow ended up writing over my script. I'm pretty sure this is it:

ConvertToYV12(interlaced=true).AssumeTFF()
ColorMatrix()
ConvertToRGB32()
Colormill(25700, 25700, 25700, 25700, 25700, 25700, 25700, 25700, 25700, 28505, 25700, 25700, 25700, 1124, 2053)
ConvertToYV12()
Tweak(hue=0, sat=1.2, bright=3, cont=1.1)

https://files.videohelp.com/u/192617/VirtualDub_Color_Mill.vdscript

[jagabo]

Mabye:

ColorYUV(gain_y=30, off_y=-15, cont_u=400, cont_v=500).Tweak(hue=-12)
ConvertToRGB().RGBAdjust(r=0.95, b=0.95).ConvertToYV12() # RGB white balance

Some shots are way over saturated with this though.

[jda]

Mabye:

ColorYUV(gain_y=30, off_y=-15, cont_u=400, cont_v=500).Tweak(hue=-12)
ConvertToRGB().RGBAdjust(r=0.95, b=0.95).ConvertToYV12() # RGB white balance

[Attachment 43709 - Click to enlarge]

Some shots are way over saturated with this though.

How does this look?

Before:

[Attachment 43724 - Click to enlarge]

After:

[Attachment 43725 - Click to enlarge]