Chroma Key Screen Color Analysis

Screen Color Analysis Window

Chroma Key Screen Color Analysis

1: The embedded ICC profile in the image.

2: Optimal HSB Screen range This is the best range for HSB for the ICC profile that the image was saved with. If you set up your chroma key backdrop so the values fall in this range then it will give you the best overall extractions. Screen shot with this lighting will extract with good transparency masks, have lower color spill, and best avoid light or dark edge haloing.

3: Average HSB values for your screen These are the values that you want to monitor.

4: Average RGB values for your screen This is more for reference only. You should optimize your screen setup to achieve the optimal HSB values, not RGB values. If the HSB value are optimal then the RGB values will be optimal as well.

5: Hue Diagram This shows where your screen is in the hue spectrum. It also shows a reference to the optimal hue range for the embedded ICC profile.

Mathematically, 120 is the optimal hue for green screen and 240 is the optimal hue for blue screen. This holds true for all color profiles. However, for green screen, the hue tends to be a little lower than 120 for Adobe 1998 RGB and a little higher than 120 for sRGB. For blue screen, most chroma key screen are typically a little less than 240 and doesn't change much regardless of profile. As long as the hue stays reasonably close to the optimal range then it should be OK.

For green screen, below 100 or above 150 is where you should be concerned. If you screen hue is below 100 then you start losing color separation between the screen and the hair and can lose detail in the extraction.

When the hue is above 150 then the screen is closer to cyan then it is to green. This is either because then screen itself is not a true chroma key green or the white balance is off. White balance being off is a common issue when shooting green screen using auto white balance on the camera. The camera sees so much green in the image that it decides it need to shift the color temperature. For green screen, always shoot using custom WB mode or flash WB mode. Also, if you shoot raw then you can adjust the white balance non-destructively after shooting because the white balance is not directly applied to the image in raw mode.

For blue screen, try to keep you setup above 210 for hue. When the hue drops below 210 then this is closer to cyan than to blue. In this case, EZ green Screen switches the algorithm in a special "cyan" mode. The extractions are usually still decent but it is best if the hue stays above 210. Some blue screen labeled as "chroma key" are actually quite a bit off in color and shoot with a hue below 210. Chroma key screen are rarely too high for hue. Good chroma key blue screens will typically shoot from 225-240 on hue, assuming the white balance is correct.

6: Warnings and Cautions If anything in your screen color falls to far out of range then this will be shown in the section. For any caution messages, they usually don't cause any major issues with extractions. The cautions let you know that the screen color is borderline for a certain metric. For any warnings, this is indicating that the screen could potentially have issues with the extractions. EZ Green Screen is pretty good about compensating for a wide range of screen variation. However, when the screen color is too far off then you may start losing quality in the extractions.

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