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Showing results for tags 'green'.
Shot vertically to capture more resolution during green screen work (in my living room with two LED panels of the cheapest kind). Main song hook recorded in one take although there's a cut-away in the edit during the bridge of the song. Sony A6000 with the 55mm 1.8. Tunnel shots done on Panasonic GH2 and severe editing in After Effects for the light beams with text.
We wanted to try compositing basic 3D VFX in the background with GH4 4K video (inspired by videogames I used to write). I used 3DS Max to create a simple scene with an alpha channel and tried to composite everything in Premiere Pro CC. Unfortunately, PPro (and AE) have issues with the 3DSMax alpha channel (not a premultiplied color issue) and the low levels of the alpha channel appear to get clipped, cutting off subtle glows, etc., making correct compositing impossible. So I moved the background plate into 3DS Max and rendered the 3D elements directly on top. I had originally planned for a much more complex 3D scene, including having objects come out of the background and go around her head, but the time spent trying to work around the compositing issue took too much time.
It appears the issue with Slog2 and S-gamut with the A7S is related to the nonlinear S-gamut Color Mode. My current work-around is to use Cinema Color Mode. If there is a significant benefit to using S-gamut, it appears some kind of 3D LUT is needed to fix it. I few years ago I wrote custom software to do 3D color correction (for stereoscopic 3D images). The 3D color cube was directly displayed and could be edited, and it was also possible to render color swatch slices to check for issues with clipping (cube elements outside the unit cube space) or other mapping issues (such as color merging leading to banding/quantization). Color cube display (unedited / unit-normalized cube shown (actual distorted cube for current color correction not shown)): Color swatches (cube slices) showing range/clipping issues: It may be possible to fix the S-gamut color mode issue by creating a 3D LUT which fixes the green/yellow splotches in skintones and perhaps also the magenta splotches in shadows. Since green and magenta are color complements, it kind of has the feel from physics describing a form of instability. That is, the system is stable in a narrow range, and when outside that range it becomes unstable, going extremely green or magenta, depending on which side of the parabolic curve center the color(s) are on. [edit: hosted pics on my server]
Using picture profile 7 on the A7S uses Slog2 Gamma and S-Gamut Color Mode. This can result in green/yellow splotches on skintones after converting Slog2 into something that looks close to Rec709. WB settings in camera or after correction in post don't appear to matter: only certain shades of skintones have the color issues. While this can be fixed with qualifier color range correction tools, that's a lot of extra work. I found that changing the Color Mode to Cinema appears to fix the color issue (Pro Color Mode also looks pretty good). It's not clear how this might affect dynamic range (figure primarily related to gamma/luma), as that's a major point of using Slog2, however so far the results look pretty good.