LUT View

[clint]

It would be nice to be able to switch back and forth in realtime with a LUT exported from Da vinci.

[g3gg0]

uhm, what?

[clint]

right.  I was a bit vague.  It would be wonderful if I could use a 1D or 3D LUT while previewing/capturing footage on my cameras LCD screen.  Nothing that would effect the video, just the preview/playback when enabled.  I could get a rough idea of how my light would be effected with the transforms from my color grade.  Perhaps its a bit much to press on the digic procs, but I had hoped it would be worth checking into.

[tupp]

The picture style used for the LCD can be different than the picture style used in recoding.

[clint]

Great point.  They do exactly that!  Where LUTs would improve upon that would be that LUTs are an industry tool used in many different pieces of software, where as picture styles are only relevant to canon cameras.

What LUT previewing on your LCD screen would allow:  You could grade a shot in a popular color editing suite then export the LUT of the grade to the camera.  Once on the camera, you could preview the color of the shot (roughly) while recording, as it will appear once you apply the color correction to it.  You'll need similar lighting, but would be extremely helpful.

[ItsMeLenny]

If you write the code I'm sure somebody would port it in.

[g3gg0]

its simple:
YUV -> RGB -> LUT -> RGB -> YUV
or alternatively
RAW -> camera matrix -> RGB -> LUT -> RGB -> YUV

can be done as module that peeks LV buffer and processes that data.

in general a simple image post-processing module would be interesting.
not permanent things, just some kind of preview like i.e.
- Brightening/Darkening (to check how much areas are under/overexposed)
- color correction

could be moved there too once you have a stable module:
- fisheye
- HDR simulation
- dual iso preview (?)

[a1ex]

The display filter interface was done for this kind of processing: alter the LiveView image in some way (usually by applying some image filter on the source buffer).

It's not exactly fast, and it's limited to running one filter at a time (for obvious reasons). As an improvement, it can be made double-buffered to fix the tearing artifact.

Some things like brightness or saturation may work best from the hardware controls (Display menu).

[g3gg0]

right, should be evaluated if its necessary to do it in realtime, or if its sufficient for REviewing pictures.
i personally often use the SET+SCROLL brightening feature, especially in bright situations where it is hard to tell if the dark areas are properly exposed.
when shooting dual_iso ist most likely is, but also then i would love to get a feeling how good the dark areas are exposed.

thus the thought to make it a separate module.

[Audionut]

I use this in zebra.c

int underexposed = ev_to_raw(- (raw_info.dynamic_range - 100) / 115.0);

Seems to move the underexposed zebras, more inline with reasonable noise levels in the shadows, rather then SNR=1.  This way, there is no need for brightness adjustments or whatever else in  image review.

Ideally, I would like to make the underexposed zebras user adjustable.  -11 EV, -9 EV, -5 EV, whatever.  But I still have some learning to do.  And some transparency.

[clint]

comp artists and colorists normally have a fast way to disable/enable a LUT (nuke & shake).  if there is a way to assign toggling the LUT on/off to a hardware button that would be great.

is there a measured documented device color profile for the canon's camera LCDs?  It could help provide a more accurate LUT overview, if we incorporated some kind of color management....just dreaming.