Image Preparation Dialog

Image Preparation Dialog

The image preparation dialog allows the incoming images from disk to be modified before they are cached in RAM for replay and tracking. The dialog is launched either from the open-shot dialog, or from the Shot/Image Preparation menu item.

Like the main SynthEyes user interface, the image preparation dialog has several tabs, each bringing up a different set of controls. The Stabilize tab is active above. With the left button pushed, you can review all the tabs quickly.

For more information on this panel, see the Image Preparation and Stabilization sections.

Warning: you should be sure to set up the cropping and distortion/scale values before beginning tracking or creating rotosplines. The splines and trackers do not automatically update to adapt to these changes in the underlying image structure, which can be complex. Use the Apply/Remove Lens Distortion script on the main Script menu to adapt to late changes in the distortion value.

Shared Controls

OK. Button. Closes the image preprocessing dialog and flushes no-longer-valid frames the RAM buffer to make way for the new version of the shot images. You can use SynthEyes's main undo button to undo all the effects of the Image Preprocessing dialog as a unit, or then redo them if desired.

Cancel. Button. Undoes the changes made using the image preprocessing dialog, then closes it.

Undo.  Button. Undo the latest change made using the image preprocessing panel. You can not undo changes made before the panel was opened.

Redo.  Button. Redo the last change undone.

Final. Button. Reads either Final or Padded: the two display modes of the viewport. The final view shows the final image coming from the image preparation subsection. The padded view shows the image after padding and lens undistortion, but before stabilization or resampling.

Both. Button. Reads either Both, Neither, or ImgPrep, indicating whether the image prep and/or main SynthEyes display window are updated simultaneously as you change the image prep controls. Neither mode saves time if you do not need to see what you are doing. Both mode allows you to show the Padded view and Final view (in the main camera view) simultaneously.

Margin. Spinner. Creates an extra off-screen border around the image in the image prep view. Makes it easier to see and understand what the stabilizer is doing, in particular.

Show. Button. When enabled, trackers are shown in the image prep view.

Image Prep View. Image display. Shows either the final image produced by the image prep subsystem (Final mode), or the image obtained after padding the image and undistorting it (Padded mode). You can drag the Region-of-interest (ROI) and Point-of-interest (POI) around, plus you can click to select trackers, or lasso-select by dragging.

Playbar (at bottom)

Preset Manager. Drop-down. Lets you create and control presets for the image prep system, for example, different presets for the entire shot and for each moving object in the shot.

Preset Mgr. Disconnect from the current preset; further changes on the panel will not affect the preset.

New preset. Create and attach to a new preset. You will be prompted for the name of the new preset.

Reset. Resets the current preset to the initial settings, which do nothing to the image.

Rename. Prompt for a new name for the current preset.

Delete. Delete the current preset.

Your presets. Selecting your preset will switch to it. Any changes you then make will affect that preset, unless you later select the Preset Mgr. item before switching to a different preset.

Rewind.  Button. Go back to the beginning of the shot.

Back Key.  Button. Go back to the previous frame with a ROI or Levels key.

Back Frame.  Button. Go back one frame; with Control down, back one key; with Shift down, back to the beginning of the shot. Auto-repeats.

Frame. Spinner. The frame to be displayed in the viewport, and to set keys for. Note that the image does not update while the spinner drags because that would require fetching all the intermediate frames from disk, which is largely what we’re trying to avoid.

Forward Frame. Button. Go forward one frame; with Control down, forward one key; with Shift down, forward to the end of the shot. Auto-repeats.

Forward Key. Button. Go forward to the next frame with a ROI or Levels key.

To End. Button. Go to the end of the shot.

Make Keys.  Checkbox. When off, any changes to the levels or region of interest create keys at frame zero (for when they are not animated). With the checkbox on, keys are created at the current frame.

Enable. Button (stoplight). Allows you to temporarily disable levels, color, blur, downsampling, channels, and ROI, but not padding or distortion. Use to find a lost ROI, for example. Effective only within image prep.

Rez Tab

Blur. Spinner. Causes a Gaussian blur with the specified radius, typically to minimize the effect of grain in film. Applied before down-sampling, so it can eliminate artifacts.

Hi-Pass. Spinner. When non-zero, creates a high-pass filter using a Gaussian blur of this radius. Use to handle footage with very variable lighting, such as explosions and strobes. Radius is usually much larger than typical blur compensations. Applied before down-sampling.

DownRez. Drop-down list: None, By 1/2, By 1/4. Causes the image from disk to be reduced in resolution by the specified amount, saving RAM and time for large film images, but reducing accuracy as well.

Interpolation. Drop-down list. Bi-Linear, 2-Lanczos, 3-Lanczos. The bi-linear method is fastest but softens the image slightly. If the shot has a lot of noise, that can be a good thing. The 2-Lanczos filter provides a sharper result, after a longer time. The 3-Lanczos filter is even sharper, with more time and of course the noise is made sharper also.

Channel. Drop-down list: RGB, Luma, R, G, B, A. Allows a luminance image to be used for tracking, or an individual channel such as red or green. Blue is usually noisy, alpha is only for spot-checking the incoming alpha. This can reduce memory consumption by a factor of 3.

Invert. Checkbox. Inverts the RGB image or channel to improve feature visibility.

Levels Tab

High. Spinner. Incoming level that will be mapped to full white in RAM. Changing the level values will create a key on the current frame if the Make Keys checkbox is on, so you can dynamically adjust to changes in shot image levels. Use right-click to delete a key, shift-right-click to truncate keys past the current frame, and control-right-click to kill all keys. High, Mid, and Low are all keyed together.

Mid. Spinner. Incoming level that will be mapped to 50% white in RAM. (Controls the effective gamma.)

Low. Spinner. Incoming level that will be mapped to 0% black in RAM.

Gamma. Spinner. A gamma level corresponding to the relationship between High, Mid, and Low.

Saturation. Spinner. Controls the saturation (color gain) of the images, without affecting overall brightness.

Hue. Spinner. Rotates the hue angle +/- 180 degrees. Might be used to line up a color axis a bit better in advance of selecting a single-channel output.

Cropping Tab

Left Crop. Spinner. The amount of image that was cropped from the left side of the film.

Width Used. Spinner. The amount of film actually scanned for the image. This value is not stored permanently; it multiplies the left and right cropping values. Normally it is 1, so that the left and right crop are the fraction of the image width that was cropped on that size. But if you have film measurements in mm, say, you can enter all the measurements in mm and they will eventually be converted to relative values.

Right Crop. Spinner. The relative amount of the width that was cropped from the right.

Top Crop. Spinner. The relative amount of the height that was cropped.

Height Used. Spinner. The actual height of the scanned portion of the image, though this is an arbitrary value.

Right Crop. Spinner. The relative amount of the height that was cropped along the bottom.

Effective Center. 2 Spinners. The optic center falls, by definition, at the center of the padded-up (uncropped) image. These values show the location of the optic center in the U and V coordinates of the original image. You can also change them to achieve a specified center, and corresponding cropping values will be created.

Stabilize Tab

For more information, see the Stabilization section of the manual.

Get Tracks. Button. Acquires the path of all selected trackers and computes a weighted average of them together to get a single net point-of-interest track.

Stabilize Axes:

Translation. Dropdown list: None/Filter/Peg. Controls stabilization of the left/right and up/down axes of the stabilizer, if any. The Filter setting uses the cut frequency spinner, and is typically used for traveling shots such as a car driving down a highway, where features come and go. The Pegged setting causes the initial position of the point of interest on the first frame to be kept throughout the shot (subject to alteration by the Adjust tracks). This is typical for shots orbiting a target.

Rotation. Dropdown list: None/Filter/Peg. Controls the stabilization of the rotation of the image around the point of interest.

Cut Freq(Hz). Spinner. This is the cutoff frequency (cycles/second) for low-pass filtering when the peg checkbox(es) are off. Any higher frequencies are attenuated, and the higher they are, the less they will be seen. Higher values are suitable for removing interlacing or residual vibration from a car mount, say. Lower values under 1 Hz are needed for hand-held shots. Note that below a certain frequency, depending on the length of the shot, further reducing this value will have no effect.

Auto-Scale. Button. Creates a Delta-Zoom track that is sufficient to ensure that there are no empty regions in the stabilized image, subject to the maximum auto-zoom. Can also animate the zoom and create Delta U and V pans depending on the Animate setting.

Animate. Dropdown list: Neither/Translate/Zoom/Both. Controls whether or not Auto-Scale is permitted to animate the zoom or delta U/V pan tracks to stay under the Maximum auto-zoom value. This can help you achieve stabilization with a smaller zoom value. But, if it is creating an animated zoom, be sure you set the main SynthEyes lens setting to Zoom.

Maximum auto-zoom. Spinner. The auto-scale will not create a zoom larger than this. If the zoom is larger, the delta U/V and zoom tracks may be animated, depending on the Animate setting.

Clear Tracks. Button. Clears the saved point-of-interest track and reference track, turning off the stabilizer.

Lens Tab

Get Solver FOV. Button. Imports the field of view determined by a SynthEyes solve cycle, or previously hand-animated on the main SynthEyes lens panel, placing these field of view values into the stabilizer's FOV track.

Field of View. Spinner. Horizontal angular field of view in degrees. Animatable. Separate from the solver's FOV track, as found on the main Lens panel.

Focal Length. Spinner. Camera focal length, based on the field of view and back plate width shown below it. Since plate size is rarely accurately known, use the field of view value wherever possible.

Plate. Text display. Shows the effective plate size in millimeters and inches. To change it, close the Image Prep dialog, and select the Shot/Edit Shot menu item.

Get Solver Distort. Button. Brings the distortion coefficient from the main Lens panel into the image prep system's distortion track. Note that while the main lens distortion can not be animated, this image prep distortion can be. This button imports the single value, clearing any other keys. You will be asked if you want to remove the distortion from the main lens panel, you should usually answer yes to avoid double-distortion.

Distortion. Spinner. Removes this much distortion from the image. You can determine this coefficient from the alignment lines on the SynthEyes Lens panel, then transfer it to this Image Preparation spinner. Do this BEFORE beginning tracking. Can be animated.

Scale. Spinner. Enlarges or reduces the image to compensate for the effect of the distortion correction. Can be animated.

Apply distortion. Checkbox. Normally the distortion, scale, and cropping specified are removed from the shot in preparation for tracking. When this checkbox is turned on, the distortion, scale, and cropping are applied instead, typically to reapply distortion to externally-rendered shots to be written to disk for later compositing.

Adjust Tab

Delta U. Spinner. Shifts the view horizontally during stabilization, allowing the point-of-interest to be moved. Animated. Allows the stabilization to be “directed,” either to avoid higher zoom factors, or for pan/scan operations. Note that the shift is in 3-D, and depends on the lens field of view.

Delta V. Spinner. Shifts the view vertically during stabilization. Animated.

Delta Rot. Spinner. Degrees. Rotates the view during stabilization. Animated.

Delta Zoom. Spinner. Zooms in and out of the image. At a value of 1.0, pixels are the same size coming in and going out. At a value of 2.0, pixels are twice the size, reducing the field of view and image quality. This value should stay down in the 1.10-1.20 range (10-20% zoom) to minimize impact on image quality. Animated. Note that the Auto-Scale button overwrites this track.

Output Tab

Resample. Checkbox. When turned on, the image prep output can be at a different resolution and aspect than the source. For example, a 3K 4:3 film scan might be padded up to restore the image center, then panned and scanned in 3-D and resampled to produce a 16:9 1080p HD image.

New Width. Spinner. When resampling is enabled, the new width of the output image.

New Height. Spinner. The new height of the resampled image.

New Aspect. Spinner. The new aspect ratio of the resampled image. The resampled width is always the full width of the zoomed image being used, so this aspect ratio winds up controlling the height of the region of the original being used. Try it in “Padded” mode and you’ll see.

4:3. Button. A convenience button, sets the new aspect ratio spinner to 1.333.

16:9. Button. More convenience, sets the new aspect ratio to 1.778.

Save Sequence. Button. Brings up a dialog which allows the entire modified image sequence to be saved back to disk.

Apply to Trkers. Button. Takes whatever all the stabilization system is doing to the image, and does the same thing to the trackers, so that they will still be in the same place in the main SynthEyes interface. Used to avoid retracking after stabilizing a shot. Do not hit more than once!

Remove f/Trkers. Button. Assuming you’ve already hit the Apply button above, this removes the effect of the stabilization. You must do this before changing the stabilization around again, then re-Apply it.

Region of Interest (ROI)

Hor. Ctr., Ver. Ctr. Spinners. These are the horizontal and vertical center position of the region of interest, ranging from -1 to +1. These tracks are animated, and keys will be set when the Make Keys checkbox is on. Normally set by dragging in the view window. A smaller ROI will require less RAM, allowing more frames to be stored for real-time playback. Use right-click to delete a key, shift-right-click to truncate keys past the current frame, and control-right-click to kill all keys.

Half Width, Half Height. Spinners. The width and height of the region of interest, where 0 is completely skinny, and 1 is the entire width or height. They are called Half Width and Height because with the center at 0, a width of 1 goes from -1 to +1 in U,V coordinates. Use Control-Drag in the viewport to change the width and height. Keyed simultaneously with the center positions. Use right-click to delete a key, shift-right-click to truncate keys past the current frame, and control-right-click to kill all keys.

Save Processed Image Sequence Dialog

Launched from the Save Sequence button on the Output tab.

… Button. Click this to set the output file name to write the sequence to. Make sure to select the desired file type as you do this. When writing an image sequence, include the number of zeroes you wish in the resulting sequence file names. For example, seq0000 will be a four-digit image number, starting at zero, while seq1 will have a varying number of digits, starting from 1.

Compression Settings. Button. Click to set the desired compression settings, after setting up the file name and type. Subtle non-SynthEyes Quicktime “feature:” the H.264 codec requires that the Key Frame every … frames checkbox in its compression settings must be turned off. Otherwise the codec produces only a single frame!

RGB Included. Checkbox. Include the RGB channels in the files produces (should usually be on).

16bit/channel. Checkbox. Produce 16 bit/channel files. Possible only if the source is 16 bit/channel.

Alpha Included. Checkbox. Include the alpha channel in the output. Can be turned on only if the output format permits it. If the input images do not contain alpha data, it will be generated from the roto-splines and/or green-screen key. Or, if (only after) you turn off the RGB Included checkbox, you can turn on the Alpha Included checkbox, and alpha channel data will be produced from the roto-spline/green-screen and converted to RGB data that is written. This feature allows a normal black/white alpha-channel image to be produced even for formats that do not support alpha information, or for other applications that require separate alpha data.

Start. Button. Get going…

Cancel. Button. Stop when next convenient. For image sequences on multi-core processors, this can be several frames later because frames are being generated in parallel.