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Table of Contents

This page provides information on the V-Ray Frame Buffer and its features.

Overview


The VFB is much more than a render image holder window. The new enhanced version provides a higher level of post processing adjustments and ability to modify your scene from inside the VFB. Here is a list of old and new benefits you should know:

  • Image preview:
    Loads render elements channels via a dropdown list;
    Works with display corrections;
    Loads various 8bit and 32bit file formats, including V-Ray resumable files;
    Image comparison between 2 or 4 renders;
  • Image management:
    Keeps the rendered image in full 32-bit floating point format;
    Can store history of rendered images with their post rendering corrections;
    Can save corrected output to various image formats;
  • Image editing and post processing:
    Set Color Corrections to rendered image and its elements;
    Composite mode for Back to Beauty workflow including layers corrections;
    LightMix control on lights contribution in the rendered image;
    Applying Proportion Guides on the rendered image;
  • Scene editing:
    Can modify actual lights values by transferring updated intensity and color from LightMix mode;
    IPR camera navigation and focus control from inside VFB;
  • Render management:
    Denoiser control;
    Region rendering control;
    Allows you to choose the order in which the buckets are rendered;
    Automatic render resolution adjustment in IPR when the VFB window is resized;

To use the VFB for rendering, create a V-Ray Renderer node.

VFB also has some limitations which are listed in the Notes section below.



VFB Menu


The V-Ray Frame Buffer menu holds the main frame buffer commands. Some of the options are also available in the VFB toolbar for a quick access.


Menu

Menu Options

File

Save current channel – Saves the currently loaded channel to an image file format.

Save all image channels to separate files – Saves all the render elements to separate files.

Save all image channels to single file – Saves the image to a single multi-channel EXR or .vrimg file.

Load image – Opens an image file to be previewed in the V-Ray Frame Buffer.

Batch image processing – Allows processing of multiple .vrimg files with the same layer tree changes at the same time.

Save all image channels to separate files options

Save VFB color corrections to render elements – When enabled, all color corrections are saved to the render channels (as opposed to only the RGB and effectsResult channels).

Batch image processing


Input folder – Specifies a path to start images.

Output folder – Specifies a path for the output images.

Layer preset – Specifies a layer tree corrections preset.

Output filenames suffix – Specifies a suffix added to the output image filenames.

Overwrite existing – Enables overwrite of existing files with the same name in the output folder.

Render

Start interactive rendering – Starts IPR.

Abort rendering – Stops the current rendering.

Render – Starts rendering.

Image

Follow mouse – Renders the closest bucket found to the mouse pointer, when using the bucket image sampler. If the progressive sampler is used, V-Ray samples the closest pixels to the mouse pointer.

Follow mouse – Drag the mouse over the VFB while rendering to change what part of the image is sampled first;
Follow mouse (locked) – Locks the bucket (or sampling) starting point.

Copy current channel to clipboard – Copies the current channel to the clipboard.

Clear image – Clears the contents of the frame buffer. This is useful when starting a new render to prevent confusion with the previous image.

View

Display color space –Specifies the color space, in which the image is displayed.

None – Does not specify a color space;
sRGB – Displays the image in sRGB color space;
OCIO – Displays the image in a color space loaded from an OCIO configuration file. See the VFB OCIO Control through Python for more information;
ICC – Displays the image in a color space loaded from an ICC configuration file;
Gamma 2.2 – Displays the image in Gamma 2.2 color space.

Zoom VFB – Zooms in/out the rendered image in the VFB.

Zoom 50% – Zooms out to 50%;
Zoom 100% – Zooms to 100%. Alternatively, double-click in the VFB with the left mouse button;
Zoom 150% – Zooms in to 150%.
Zoom to fit – Zooms the current image to fit in the VFB. If Render Region is active – zooms to the region.

Channels – Chooses which channels to see.

View red channel – Displays the red channel;
View green channel – Displays the green channel;
View blue channel – Displays the blue channel;
Switch to alpha channel – Displays the alpha channel;
Monochromatic mode –Displays the image in monochromatic mode.

Color clamping – Opens the color clamping submenu options:

Force color clamping – Forces color clamping;
View clamped colors – Displays the clamped colors.

Use pixel aspect – Enables visualization of the pixel aspect ratio.

Flip – Mirrors the image in the VFB. This is a view only option, the flipped image cannot be exported. This function is only active while holding the menu button or the hotkey for the corresponding type of flip. The effect does not interrupt interactive rendering.

Flip horizontally – Mirrors the image horizontally.

Flip vertically – Mirrors the image vertically.

Panorama View – Shows the image in 360° view.

Show History – Shows the History panel.

Show Layers – Shows the Layers panel.

Options

VFB settings – Opens the VFB Settings window where you can adjusts settings for Render View, Render Region, History, Layers, and Shortcuts.


VFB Toolbar


This dropdown gives access to render elements rendered for the scene. The selected render element is displayed in the VFB. By default, the RGB color and Alpha render elements are available. Any additional render elements that have been added to the scene also appear in the drop-down.

Displays the coordinates of the mouse pointer.

Specifies the sampled area size. Click on the arrow to open a context menu with the available sampled area sizes: 1x1, 3x3, 5x5, and 7x7.

Specifies the color of the pixel under the current mouse position before applying any color corrections.

Displays the RGB pixel values at the current mouse pointer position before applying any color corrections.

Specifies RGB values. Click on the arrow to open a context menu with the available option.

None – Does not specify the RGB value.
HSV – Specifies the Hue, Saturation and Value of the pixel under the current mouse position.
Web – Specifies the HEX of the pixel under the current mouse position.
8bit – Specifies the 8bit color palette of the pixel under the current mouse position.

Displays the Hue, Saturation and Value of the pixel under the current mouse position when HSV is selected.

Displays the HEX of the pixel under the current mouse position when Web is selected.

Displays the 8bit color palette of the pixel under the current mouse position when 8bit is selected.

Locks the mouse pointer coordinates and displays information for the selected pixel.

Shows corrected colors.

Shows the V-Ray log.

Displays the red channel.

Displays the green channel.

Displays the blur channel.

Displays the Alpha channel.

Saves the image to disk. Press and hold the icon to bring up the submenu:

Save current channel – Saves the current channel to an image file format;
Save all image channels to separate files – Saves all the render elements into separate files;
Save all image channels to single file – Saves the image into a single multi-channel EXR or .vrimg file.

Clears the contents of the frame buffer. This is useful when starting a new render to prevent confusion with the previous image.

Renders the closest bucket found to the mouse pointer, when using the bucket image sampler. If the progressive sampler is used, V-Ray samples the closest pixels to the mouse pointer. With this option enabled, you can right-click on the image and select Lock bucket starting point to lock the bucket (or sampling) starting point.

Allows you to render regions in the VFB. See the Render Region section for more information.

Starts IPR. If there is more than one camera in the scene, hold left mouse button to display a list of the available cameras.

Stops the current rendering.

Starts rendering. If there is more than one camera in the scene, hold left mouse button to display a list of the available cameras.

Render History


The V-Ray VFB keeps a history of previously rendered images, and lists each with a number, thumbnail, and textual details in the Render history panel. Up to four images can be called from the history to be compared in the VFB (as shown below). History files are stored as .vrimg files in a user-specified folder. Render history settings can be configured in the VFB Settings window.






Enables or disables image A/B vertical comparison. Select images A and B from the render history.

Enables or disables image A/B horizontal comparison. Select images A and B from the render history.

Enables or disables image A/B/C/D comparison. Select images A, B, C and D from the render history.

Saves the current image from the VFB to the render history. The image is placed at the top of the render history list.

Loads the selected image from the render history to the VFB.

Removes the selected image from the render history.

A search field where you can filter the images based on the scene paths and notes. The filter text is selected when pressing the Enter from the keyboard.

The keyboard keys from 1 to 9 can be used to quickly load the first 9 images from the history to the VFB.


The History panel with notes/name, resolution/time, and shortcut key info displayed. Right-clicking on an image in the VFB history brings up a pop-up menu with some useful options.


Image Info window 



The History panel with notes/name, resolution/time, and shortcut key info displayed. Right-clicking on an image in the VFB history brings up a pop-up menu with some useful options.

Edit note – Allows you to add a text comment to the image; the comment appears below the image.

Set A – Sets the render as A image for A/B comparison.

Set B –  Sets the render as B image for A/B comparison.

Load to VFB – Loads the selected image in the VFB (same as double-clicking on the image).

Delete – Deletes the selected image from history. The image is moved to the system's Recycle Bin and can be restored from there if needed.

Load layers – Loads the layer tree preset of the selected image.

Load V-Ray settings – Loads the V-Ray settings used for the  saved render.

Compare V-Ray settings – Opens the Compare V-Ray settings dialogue, where you can compare the render settings of saved renders.

Copy scene path – Copies the full path to the scene.

Copy project path – Copies the full path to the project.

Reload history – Re-reads the history image list. This may be needed if the history folder is updated outside of Houdini (e.g. from another Houdini session).

Manually saved .vrimg files can also be added to the History folder, but they need to be saved with all image channels in one .vrimg file to keep the complete image info.


Layers


The redesigned V-Ray Frame Buffer includes a suite of color corrections and tools for adjusting the image. The tools are added as layers and displayed in a layer tree. You can enable or disable a particular tool using the visibility icon () to the left of its name.

For more information on using the Layers, see the Layers page.






Creates a layer. Multiple layers of the same type can be added.

Folder – Allows grouping multiple layers;
Background – Adds a background color correction layer;
Render Element – Selects a render element from your image that you can use in compositing. This is only available when the Source layer is set to Composite;
Constant – Adds a solid color that can be used to achieve an effect on another layer (for example to multiply by the constant);
Exposure – Adds an Exposure color correction layer;
White Balance – Adds a White Balance color correction layer;
Hue/Saturation – Adds a Hue/Saturation color correction layer;
Color Balance – Adds a Color Balance color correction layer;
Curves – Adds a Curves color correction layer;
Lookup Table – A Lookup Table layer allows loading a LUT file for color transformations;
Filmic Tonemap – Contains different types of mapping curves and gamma corrections. Also allows selection of a color space.
Integer mask elementMask is used with integer render elements like VRayRenderID, VRayObjectID, and VRayMtlID Render Elements.
MultiMatte mask elementMask is based on the MultiMatte Render Element.
Cryptomatte mask elementMask is based on the VRayCryptyomatte Render Element.
Proportion Guides – Adds a proportion guide layer.

For more information, see the Layers page.

Deletes the selected layer(s).

Saves a layer tree preset.

Loads a layer tree preset.

Quick access to custom layer presets. You must set the path to it in the VFB Settings.

Undo various actions related to layers such as create, delete, reorder or modify a layer.

Redo various actions related to layers such as create, delete, reorder or modify a layer.


Each layer has a context menu. Right-click to display it:







Command
Description
ResetResets all changes done to the selected layer.
SaveSaves the layer as a preset.
LoadLoads a preset for the selected layer.
DeleteDeletes the selected layer.
Save as LUTBakes all the color corrections to a LUT file.
New LayerCreates a new layer.
DuplicateDuplicates the selected layer.
Blend ModesSpecifies how the selected layer blends with the result from all layers below it.


Stats


The V-Ray Frame Buffer allows monitoring of different statistics and information about your scene in the Stats panel. The exact contents of the Stats changes depending on the scene,  the rendering mode (interactive vs production, bucket vs progressive) and others.

Right-click to display a context menu, allowing you to copy the Stats values.




Log


The Log panel provides messages about the render process. Verbosity control is available and you can filter the type of messages shown in the Log: AllError OnlyError & Warnings, or Error, Warnings & info. Additional options are available when you click on the Open options  button:

Show progress – Shows a completion percent of each task (e.g. building Light Cache).

Wrap – Wraps longer lines in order to avoid horizontal scroll.

Undock – Docks/undocks the Log tab.

Note that the V-Ray Log is also accessible via the Show log button.

The Log tab can be detached and used as a separate window or docked elsewhere.

Ctr+F opens a search field at the bottom of the Log tab.




VFB Shortcuts


These shortcuts navigate through the VFB image. Please note that the VFB window must have the current focus for the shortcuts to have effect:



DescriptionShortcut Key
GlobalShow/hide historyH
Show/hide only layers treeP
Show/hide whole right panelCtr+L
Toggle Full ScreenF11
VFB SettingsS

History/Render ViewEnable history A/B/C/D compare modeE
Enable history A/B horizontal compare modeQ
Enable history A/B vertical compare modeW

Load the respective image from the VFB history (1...9)

1; 2; 3; 4; 5; 6; 7; 8; 9

Layers/Property PanelRedoCtr+Y
UndoCtr+Z

LayersDelete a layerDel

Message LogClose SearchEsc
Find in LogCtr+F
Find nextReturn
Find previousShift+Return

Render View Abort renderingEsc
Copy current channel to clipboardCtr+C
Flip horizontallyM
Flip verticallyShift+M
Load imageCtr+O
Lock pixel info coordinatesL
Pan image (up, left, down, right)Up; Left; Down; Right (arrow keys)
Switch to Alpha channelA
View blue channelB
View green channelG
View next channelPgDown
View previous channelPgUp
View red channelR
Zoom 100%* ; Double-click left button
Zoom in+ / =
Zoom out-/_
Zoom to fitF
Zoom in the rendered imageCtrl+Shift+Left click
Zoom out the rendered imageCtrl+Shift+Right click
Symmetric render region resizingAlt+resize

Note that the keyboard shortcuts work only within the VFB window.

The shortcut keys can be modified in the VFB's options from VFB > Options > Shortcuts tab > Edit hotkeys.


Render Region


Region rendering can be used in both IPR and Production modes to isolate only part of the frame for rendering. Usually, when a render region is used, you would like to save the whole frame instead of the region only.

Saving single channel .exr files ignores the render region and always saves the full frame. This applies when saving the .exr through VFB.

Saving multi-channel .exr files writes just the render region data in the file by default but it can be set to save full frame instead. In order to save the render region with the rest of the frame, set its exr data window option to Whole Image. Saving multi-channel .exr files from VFB > Save all channels to single file saves the render region when it is enabled from the VFB. This happens even if you have selected a render region on top of the already rendered frame, without an actual region used in the rendering process. To save the full frame from VFB, disable the render region.

Find more info at VFB Render Region.


Notes


  • VFB does not display the G-Buffer layers (like Coverage etc.)  
  • VFB does not work with strip rendering.
  • VFB does not work with rendering to fields.
  • The OpenEXR file format is an open file format for high dynamic range images originally developed by Industrial Light and Magic. The official site of the OpenEXR file format is http://www.openexr.com/
  • If Lens Effects or the VRayDenoiser render element are enabled, then the RGB Color channel is saved with the name RGB_color and the effectsResult channel is saved as effectsResult when saving all channels from VFB.
  • If an 8-bit file is saved through the VFB or the Render Output / Save image settings, the color space (for example sRGB) is embedded and the image appears as in the frame buffer when loaded in an external image viewer. If a 32-bit (exr, hdr, tif) image is saved, it remains linear and relies on the external image viewer to handle the display color space.