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August 2014
Issue: June 1, 2010

REVIEW: IMAGICA'S O-GI PLUG-IN SUITE

By: Igor Ridanovic
PRODUCT: Imagica’s O-gi plug-in suite

WEBSITE: www.o-gi.biz   

PRICING: For Avid DS: floating list $1,499, nodelocked $999;
For Autodesk: floating $2,499, nodelocked $1,499; for Quantel: nodelocked $2,400      
- Powerful image quality enhancing tools
- Flexible smoothing filter
- Easy-to-use facial wrinkle and blemish removal filter

Some plug-in filters create invisible magic by quietly laboring in the background and polishing the picture. Imagica’s O-gi suite entered this essential utility category for me recently while supervising the digital intermediate on Unrequited, a feature film debut by director Jason Epperson, but more on that later. Plug-in packages often number hundreds of effects. The Imagica’s O-gi comes with only four. While this may seem like a lack of value, O-gi occupies a very specific niche traditionally filled by dedicated hardware.

WRINKLE DIMINISHER

This filter delivers more than the name promises. All of the plug-ins in the suite, except for this one, are best described as image quality augmenting filters. Wrinkle Diminisher is different. It automates complexion beauty work — a VFX task, which traditionally requires artistry and experience.
The controls are intuitive and easy to use. We create a matte for the face, apply smoothing and put grain back in the blurred areas. The filter manages to protect facial features like eyes and lips, as well as stubble on male actors’ faces. It removes crow’s feet, pores and other blemishes. Small patches of discolored skin and beauty marks tend to be excluded from the matte. The filter is also useful for hiding beads of sweat on actors’ faces and it would probably even work well for imperfections in product shots.
Wrinkle Diminisher will not put experienced artists out of business, but it does a good job when there is limited time available. It brings beauty work within reach of projects that normally could not afford days of manual work. It can also be used as a starting point for high-end jobs that require additional artist touch-ups.

SMOOTHING FILTER

The smoothing filter works well for fine to medium film grain and digital camera noise removal. It visibly removes grain from most shots, but it falls short for heavy digital noise as in underexposed Red footage.
The filter automatically generates an edge mask used to protect detail in the image. After refining the mask the user sets the amount of smoothing globally or for individual RGB channels.
I tested the filter on a variety of 35mm and Red camera shots. Regardless of the source, the edge mask needed only a minimal adjustment to strike a good balance between smoothing and detail preservation. A too “thin” mask took away detail. Aggressive smoothing made the picture noise-free but revealed low-bit-depth banding in some material. 

VIDEO SIGNAL LEGALIZER

Signal excursions outside of set standards are considered illegal. Some nonlinear editors can legalize the output signal internally. The method these native legalizers use is often fast but crude. The signal is clipped and crushed at specific values, resulting in a loss of detail. The O-gi Video Signal Legalizer avoids losing detail by compressing and remapping the signal — a technique used in better hardware processors.
This filter is designed to legalize the NTSC or PAL interpretation of the signal. Although O-gi targets the composite signal that may be encoded in the future, it by definition legalizes the Y’CbCr signal and it also legalizes the RGB gamut.
Legalizing for the least common denominator like this may save you from a QC rejection but it may also sacrifice a bit of color information. Considering that analog broadcast is going away, we should hope that Imagica will include Y’CbCr and RGB options in the future versions.

MACH BAND SUPPRESSOR

I have recently completed a digital intermediate on a psychological thriller and used the job as a test case for Mach Band Suppressor. Unrequited follows the tragic decline of Ben, an emotionally troubled teen played by Michael Welch. In a desperate attempt to win back his ex, Ben makes some poor decisions.
The DI at Kappa Studios (by colorist Brian Hutchings) in Burbank faced a common challenge — how to include low-res 8-bit material in a 2K workflow. The project contained a number of elaborate flashback scenes designed by the film editor Brock Smith. The deadline dictated that we use the low-res flashbacks instead of rebuilding them in 2K and we needed to find a way to match the flashbacks to the rest of the 4K Red material.
Avid DS scaled the shots up to 2K very well. Once projected, most of the flashbacks revealed 8-bit banding resident in the source material. The banding was visible in dissolves and color gradients. The traditional method of placing random grain in the image to hide banding worked, but it made the silky, glowing flashbacks look gritty.
Then I decided to test drive Mach Band Suppressor. In most cases the filter removed every trace of banding artifacts. Instead of applying heavy grain, it rendered smooth images free of banding. The picture looked as if a magic squeegee wiped it clean. A closer inspection showed that the filter was producing small artifacts in areas with high motion blur. A minor adjustment of the level and threshold parameters put it back on the track.
Mach Band Suppressor helped with occasional Canon 5D shots in this film, too. The 5D shots exhibited a faint grid-like pixel pattern, possibly a debayering artifact enhanced by image scaling earlier in post. The filter removed the stray pixels. Mach Band is useful, not just for fixing banding in cel animation as the O-gi manual suggests, but also for clean up of live-action material stored at low-bit-depth and encoded with lossy codecs.

FINAL THOUGHTS

O-gi doesn’t have a wide assortment of filters, but this doesn’t affect its value. Even if you end up using a single O-gi filter over and over again you will find that it performs specialized tasks like no other plug-in.

Igor Ridanovic is an LA-based HD & D-Cinema Consultant. He can be reached through his Website HDHead.com.