VSDC (or other) - how to apply gradual brighness/contrast correction?

[HubC]

Hello,

Semi-newbie here, although I have been editing videos at an amateur-level for a few years, with a number of tools.

I have a video that was digitized from an old Super8 movie way back then, with many flaws, and am trying to rework/enhance its quality.
Among the problems is this : brightness/contrast fade from left to right (the left half of the video is OK, then from the middle to the right-hand side, it gradually darkens). I am seeking a way to correct that.

Here's an example image demonstrating the problem :

[Attachment 72142 - Click to enlarge]

Currently working with free VSDC. If I have to, I could possibly obtain and learn how to use another tool, but would obviously prefer avoiding that.
Any help would be appreciated.

(and yes, the image quality suffers on many other points, which I will also address inasmuch as possible -- you can't recreate information that isn't there...)

[Selur]

no clue about VSDC, but Retinex: https://imgsli.com/MTg5MTE0 seems to work. (settings need tweaking)

[HubC]

Thanks, I'll look into that. But it seems to me that Retinex is an automatic adjustment system (with adjustable parameters).
I have already applied (not in the example above) the auto-color adjust of VSDC, with good results overall. However it doesn't fix the systematic unevenness of brightness/contrast/saturation that is depicted. At first sight, it looks to me that your Retinex example shows better balance on the right-hand side of the picture, but *at the cost* of degraded quality on the left-hand side.
What I'm after is some way to direct a color correction algorithm to be progressively more agressive as we move from left to right in the picture.

At the moment, for lack of an automatic way, I am toying with the idea of manually setting a series of vertical bands, each with its brightness/contrast/saturation correction. It's going to be a pain, and probably suboptimal, but it might work. Fortunately (?), my initial video is low-res (720 pix wide), so it appears (from early trials on a static picture) I could get away with "only" 16 such bands, getting adequate correction on the far-right border, with smooth-enoug non-visually detectable borders between the bands.

Before/After (I think I'll get slightly more agressive on the correction, and add saturation to the adjusted parameters, this is only with brightness-contrast)

[Attachment 72150 - Click to enlarge]


[Attachment 72151 - Click to enlarge]

[poisondeathray]

Does it flicker, or is it consistent temporally ?

If it's consistent, in most programs, you would use a gradient mask (make in image editor, like photoshop ,gimp)

100% white means your filter(s) are 100% applied . 0% white means your filter(s) are 0 % applied . In between is whatever % applied

You might make separate masks for luminance, saturation, hue, whatever filter etc... This falls under the categories of "compositing" and "masking", you can probably find many tutorials on youtube and similar

[HubC]

It is consistent over time (maybe not on all clips, but it's quite visible on most).
Yes, a gradient mask is exactly what I think I'm llooking for. So far, I haven't found a way to import an external mask into VSDC, much less a gradient one, I'll look again, now that you've hinted at the right keywords.

BTW, my painful manual way of making 15 masks for 15 vertical bands with 15 different values of brightness adjustment doesn't live up to expectations. The banding is way too visible (it stands out particularly as the boundaries stay put in the frame, while the video moves behind it, but it's already visible on some scenes just on a static screenshot).

I need a real gradient filter.


[Attachment 72165 - Click to enlarge]

[HubC]

Yes indeed, @poisondeathray, it seems a gradient mask is possible within VSDC.

Here's the tutorial I've found, thanks to your helpful advice on keywords of the trade :
https://www.youtube.com/watch?v=9LMRMadOEZI

It should probably do just about exactly what I need (I still need to experiment, my first two trials crashed VSDC....).

[HubC]

Yes indeed. May still need some tweaking, but it's the right tool.
(for reference, create a rectangle, fill it with the brush tool with a gradient black-white, of which you adjust the geometry, contrast, etc, then in the "blending mode" menu of that object, trial and error shows that using "Soft Light" blending mode has my desired effect.)


[Attachment 72169 - Click to enlarge]

Thank you so much !!!

[jagabo]

Find a shot that's mostly black or white in the area you want to fix. Build a mask from that.