Red Alert's resample filter vs. Red Rush

[Paul Daniel]

Hello.This is my first post on the RedUser Forum and I am relatively new to Red Camera workflow.

I am using Red Alert to export TIFF Sequences from RD3 files. My client told me that images exported from Red Rush look softer. However, I want to use Red Alert. I am almost certain that the Resample Filter in Red Alert is the culprit here.

There are 8 choices in Red Alert's Resample Filter:
CatmulRom (sharp)
Lanczos (sharp)
Gauss (smooth)
Mitchell (smooth)
Quadratic (smooth)
Cubic (smooth)
Bell (smooth)
WideGauss (smoothest)

Red Rush does not have a Resample Filter in the render settings. Does anyone know which filter Red Rush uses??

 

[Dj Joofa]

Hello.This is my first post on the RedUser I am almost certain that the Resample Filter in Red Alert is the culprit here.

Gauss (smooth)
Cubic (smooth)

It is possible that resampling is not done properly in Red Alert that is causing smoothing. I have never used Red Alert/Red Rushes, but I am surprised at the above claim of some of the filters such as Gaussian and Cubic listed as "smoothing" filters. For e.g., take the Gaussian filter, which gets implemented, say for the lack of a term, not the best way, more often than one would think. Very popular image processing software, for e.g., ImageMagick, makes similar claim for that filter, and see below the shape of the Gaussian filter (the usual bell shaped curve) used as "approximating" filter in such typical implementations (from ImageMagick):

Where as, a properly implemented Gaussian-derived filter should have little smoothing, and should look like the one on the left below. Notice, the negative lobes, which reduce the blurring/smoothing effects. (On the right is its Fourier transform, and it may be noted that how close is that to the ideal sinc interpolator.)

 

[Nick Shaw]

Red Rush does not have a Resample Filter in the render settings. Does anyone know which filter Red Rush uses??

REDrushes does have a choice of scaling filter. It's under the "Resize" settings, not the "Render" settings.

REDrushes uses REDline to do the rendering, which is the command line version of the render engine in REDAlert, so if the settings are the same the results should be the same.

 

[Paul Daniel]

Nick, thanks a lot! I appreciate you help!