Comp-Fu Answers Part 1

Welcome to my new show where I answer questions that are based on google searches that brought users to my website. (disclaimer: I’m using piwik for web site statistics and search keywords are transmitted by the user’s browser. It’s anonymous though, so relax.)

what is color space and color temperature
— anonymous

Thanks for your question, Mr Anonymous. Color Space and Color Temperature can be looked up on Wikipedia. In VFX specifically, the term color space usually means the way that a color is being split into separate channels for digital processing. RGB by default (red, green and blue channels). It can be converted back and forth to spaces like HLS, Lab, YUV and so on where you still have red, green and blue channels but now each channel contains a different color attribute. In HLS, the red channel contains a color’s hue, for example.

Color temperature is a measure for how cool or warm an image appears (top row of the image). It has a well-defined physical background but basically it’s your white balance setting. It can be adjusted in most RAW converters and although it’s not a color space you can adjust it using the TMI system which includes a magenta-green-value in addition to the orange-blue color temperature axis. It’s available in Shake and Nuke and I’ve made a macro that brings it to Fusion.

color temperature in Nuke
— anonymous

I think there’s no color temperature node in Nuke, but I adjust the temperature of an image using a Gain adjustment:

Open the gain color wheel and enable the TMI sliders if they’re not yet visible. Then, adjust the T slider to your liking. The image might appear brighter or darker now so as a second step, I use the V slider of the HSV group and bring it back to 1.0. This makes sure that the image stays as bright as before (that’s not totally true, but it’s a good rule of thumb. Of course you can tweak every slider to your liking).

I choose the ColorCorrector instead of Grade or Multiply because it has a saturation slider that is applied before the gain and can be used to make the warm or cold tint of an image stronger (if you desaturate the image completely before tinting you’re doing what Photoshop’s Hue/Saturation adjustment calls colorizing the image).

game of thrones color grading
— anonymous

That’s funny. I’m no authority but a while ago I made a blog post on that topic. And coincidentally it involves color temperature 🙂

Tags: answers, color, Fusion, Nuke

This entry was posted on Monday, May 20th, 2013 at 10:00 by Stefan and is filed under English, VFX. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.