Color Histogram / Scopes

[andresc4]

Going back to this thread regarding LUT and colors, 3d LUT colourspace mapping on a realtime video stream? - #14 by andresc4 is there any patch already done to achieve this result from a texture and to be able to see in details color information ?

If not, the theory behind will be dividing the image in rows and columns, getting and average of the intensity of each column, and displaying a 1 point measuring the luminosity of each channel? I am missing something?

[microdee]

check out the Waveform node inside mp.dx

[andresc4]

Give this guy another golden quad for best helper ever :D

[andresc4]

I need some help here… the idea is to capture a HDMI signal, add some content using VVVV, and get that HDMI signal back ( It will be SDI but its the same )

Im using a Magwell HDMI USB capture card, getting the signal from the same computer, using a shot hdmi cable, video card is a GTX1060

Using the waveform patch from @microdee found out a few interesting things, its almost impossible to get the exact same signal back regarding colors. I have all the extended range on the Nvidia driver, already try some gain and brightness settings, but its super hard to get the same result. My question is, is it a compression problem from the capture card itself ? Is there any setting on the Nvidia driver that I can play with ? I will do the same test using a BlackMagic PCI

[tonfilm]

don’t know which codec you are using, but the video probably uses YUV color space which is smaller than RGB color space. so check all places where you can set color space or compression…

[andresc4]

@tonfilm thanks ! I was missing this setting… I was sure that I did change it before, but it made no change at all. In the middle I reinstall the Magwell capture card downloading the drivers from their site, still, the driver don’t find the capture card, but I did use the inf, maybe that made it work ? not sure, but thanks to your suggestion the change was immediate, as soon as I change it to RGB the lines were on the same shape but different levels.

So I check all the Nvidia settings, and I found that some settings were a little bit off the default, 0,49 or 0,99 , I center all the sliders and it seems to work quite well now!

on the mid, max and minimum levels of that Dynamic Texture ( to avoid getting some other result due to video codecs ) It seems to be exact

Playing some videos / still pictures I do see some minimum variance on some parts of the graph, but I do not see any difference on my monitor ( I do not have a trained eye or experience on this topic but hey, I feel Spilberg now :D )

Here are all the results and the settings I use, I hope this help someone in the future

Thanks!