Full to Legal Scale vs Soft Clipping

[Mark Mulcaster]

I have a question about AAF round-trippig with the Baselight Plug-in that im hoping someone might be able to shed some additional light one.

I've always sent grades back as full to legal scale, but noticed that if i were to change the output in the baselight pluging to soft clip to legal it seems to introduce additional contrast compared to Full to legal scale. 

The way i see it is that whilst both are technical operations a soft clip affects the image more by allowing for a bit more contrast in the grade? 

From Filmlights Manual:

On full to legal:

"When image data is scaled from full to legal, full range data is scaled down to fit into the 64‐940 range. This modifies every colour value in the range."

On soft clipping:

"Soft clipping is very similar to clipping; however, values are clipped to provide a gradual, rather than a sharp, transition through the white and black levels."

So when sending a grade back to Avid for online (Broadcast rec709) I've always selected the full to legal scale option as how I understand it is we work in Baselight in Full Range and to maintain the correct grade intent technically the full to legal option scales everything to fit inside the 64-940 vales of broadcast video.

So if i were grade with the occasional sub-blacks lets say -3 would the full to legal operation clip or scale the whole image to fit the -3 black value to be 64.

 

I hope that makes sense?!

 

 

[Andy Minuth]

In most cases Full to Legal scale will be the right choice. It takes 0 and maps it to 64. In your case 10bit CV -3 will also be mapped to 64, because everything below 0 will be clipped. It maintains the information in the shadows and highlights.

The soft clip operation basically takes everything below CV 64 and above 940 and clips it. So you will loose picture details there, but the image will look more contrasty compared to Full to legal scale.