Stereo3D Ghost Toaster

Introduction

Most Stereoscopic 3D viewing systems such as Circular Polarized, and even Active Shutter-Glass to a certain extent, have traces of what is referred to as “Ghosting.” This is an undesired effect that occurs when there is leak of the left image into right eye and the right image leaks into the left. When this occurs the viewer will see a faint double image around objects within the scene. This occurs most often in high contrast areas of the picture and will create retinal rivalry, as there are severe disparities and asymmetries between the images. Some ghosting is negligible and will go undetected but if the images leakage or crosstalk is over a few percentage points from the original then the images are required to be “Ghost-Busted”, or “Ghost-Toasted” in the case of Stereo3D Toolbox. Projection systems such as Real-D are greatly affected by ghosting and must have ghost compensation added before they are ever displayed in a theatre.

Initial Setup

The Ghost Toaster plug-in, as with all the plug-ins in the Stereo3D suite, can be applied to an already pre-existing multiplexed stereo pair (left & right video files married together) that is any number of 3D formats (side-by-side, over-under, etc) as well as be applied to a single left or right eye file and then be coupled with the correct adjacent left or right video clip.

To access the Ghost Toaster plug-in go to:

Video Filters → Dashwood Stereo3D Toolbox → Stereo3D Ghost Toaster

Once applied to the clip, the clips render status will appear red in the FCP timeline unless set to Unlimited-RT. To access the menu to change the timeline’s render settings click on the RT button on the far left of the timeline. Select Unlimited-RT and the clips render status will turn orange, indicating that Final Cut Pro will process as much of the un-rendered effect in real-time as permitted by the video card. Typically the more VRAM that FCP has access to, the closer to real-time it will display the un-rendered clip. If an external 3D Monitor is being used for playback, then Playback Video Quality should be set to High and Playback Frame Rate can be left at Dynamic.
S3D Input
Please refer to either Clip Coupler or Geometry Plug-in manuals for details on how to use the S3D Input and for brief definitions of the various 3D formats.

Click the links below.

http://www.dashwood3d.com/help/stereo3d-clip-coupler/

http://www.dashwood3d.com/help/stereo3d-geometry/

Using Ghost Toaster

Operating Ghost Toaster is a simple one-slider process. It is encouraged to either use a test pattern or view the image on the final output medium to ensure the Ghost Toasting is sufficient or not over-powering.

The Slider Gang will determine the amount of crosstalk compensation added to the overall scene or to each individual eye. Setting the Slider Gang to “Gang Right % to Left” will add the same amount of crosstalk compensation to both the left and right eye files. Each value of 1 equates to 1% of the opposing image pre-compensation, as in how much of the right image will be subtracted from the left image and vice-versa. Moving the slider to the right will increase the amount of Ghost Toasting processing to the image, which pre-compensates for the opposing image to leak over. Ghost Toaster will raise the left image’s dynamic range by the sliders value and then subtract a copy of the right image with the dynamic range decreased equally from the left image to create a Ghost Toasted image. The same process will then be implemented for the right image. Each value of 1 also equates to 1% of the dynamic range loss.

Setting the Slider Gang to “Use Separate % for Right” will allow for unique adjustments to each eye. This sometimes is necessary if only one image has strong contrast.

Ghost Toaster Input Options

Input Squeezed (Only available when using Side-by-Side input types)

This option tells Stereo3D Toolbox whether or not the side-by-side footage is squeezed into one full resolution composition or if it is two full resolution compositions coupled in the same file.

Swap Inputs
The naming hierarchy of left & right 3D files can sometimes be incorrect depending on the accuracy of the Data Management Technologist’s file handling and the labeling of the physical cameras on a Beam-Splitter Rig. This naming error will be evident if the footage is viewed on a 3D display, as the background will be perceived to be floating in front of objects that should be in the foreground and vice-versa. When incorrectly labeled the left and right eye video will be reversed and thus the human eye will be receiving incorrect information. If the viewer is unsure if the footage is named properly, then by clicking Swap Input back and forth while playing the footage, the 3D will either be comfortable to watch or slightly straining to view. If the footage is comfortable to watch and the objects within the scene are positioned in the proper location in 3D space (foreground objects appearing at the front or “popping” off the screen & background objects appearing in the back or “behind” the screen) when Swap Input is selected, then this indicates that the footage has been named incorrectly.

Global Output Mode
Global Output Mode is a keen way to set and apply the same stereoscopic output mode to an entire sequence so that every clip does not have to be adjusted individually. Selecting the Use Global Output Mode check box on a specific clip ensures that that clip will adhere to whatever the current Global Output Mode is set to. To set the global output mode, select the appropriate output using the Global S3D Output Mode drop down menu, which only becomes available when Use Global Output Mode has been selected, then click the Set Global Output Mode icon.

This setting is particularly useful when a sequence needs to be edited using a viewing method such as Anaglyph and then exported out to a stereoscopic standard such as side-by-side or over-under. Ensuring that every clip in the timeline has the Use Global Output Mode checkbox selected will certify that the entire timeline will output to the correct format.

S3D Output Options

The various stereoscopic 3D output modes available in Stereo3D Toolbox can be accessed underneath the S3D Output Mode Tab. Side-by-side, Line by Line Interlaced and Above Below are the three output modes are most commonly found finishing formats besides exporting separate left and right video tracks or upgrading to a DCP for a cinema release.

These formats are discussed in the Clip Coupler & Geometry guides.

Swap Outputs
It is sometimes necessary to swap the output as some 3D Monitors interleave their polarized signals differently, amongst other reasons. If ever needed, the Swap Outputs checkbox can be selected after the convergence and stereoscopic settings have been changed.

Flip Flop
Cameras shot on certain beam splitter rigs need one or both of the cameras to be flipped or flopped in order for the perspectives to match.

Flip will rotate the image 180º so that it is upside down from it’s native position.

Flop will change the images perspective so that is a mirror image of it’s native position as though it has been rotated 180º along the z-axis.