LuxRender Interface - LuxRender Wiki
Luxrender GPL Physically Based Renderer

LuxRender Interface

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LuxRender uses a tabbed interface. By default, the Render tab is shown, but there is also a Log tab and a Network tab available. The menu and status bar are always shown, regardless of which tab has been selected.

LuxRender's interface, model by DennisH2010

Menu Bar

The menu bar items are 'file', 'render', 'view' and 'help'.


The file menu contains the following items:

  • Open - this lets you open a file with the .lxs extension
  • Open Recent - opens a scene that's been used recently
  • Resume FLM - this lets you open a .lxs file and it's corresponding .flm file in order to resume rendering of a scene. See [here] for details on resuming a render later.
  • Load FLM - this lets you open a .flm file in order to perform post-processing. It will not perform any rendering.
  • Save FLM - this lets you save the current render to a .flm file which you can use to resume a render or to perform tonemapping later.
  • Save Panel Settings - this lets you save the settings you modified in the LuxRender window (such as lens flare and noise reduction parameters) to be used later for another scene.
  • Load Panel Settings - this allows you to load a panel settings file and apply its parameters to the current scene.
  • Export to Image - this sub-menu will let you save the current render to a standard image file in several different ways (more details on each option below).
  • Exit - this exits the program

Currently LuxRender saves the output at regular intervals into the directory of the .lxs file. This is controlled with settings inside the .lxs file itself and cannot be accessed or controlled within LuxRender itself. You can change the intervals, which image types are written and settings for each image type in the various exporters (like luxblend).

Export to Image

This is a sub-menu under the file menu with the following items:

  • Tonemapped Image... - saves the exact image shown in the GUI (with all tonemapping & other filters applied) to a standard image file. You will be prompted for a file name and format. You can choose from PNG, BMP, JPEG and TIFF image types (note: some additional formats supported by Qt can be specified if you use the proper extension, file type is derived from the extension).
  • High Dynamic Range Image... - saves the photometric responses at each pixel to a floating point OpenEXR file. This preserves more detail in the image (particularly in the shadows and highlights) and is more accurate but the file will be larger and may require special software to view. Tonemapping and other filters are NOT applied when using this option. At present, only OpenEXR format is supported.
  • Light Groups to Tonemapped Images... - If you have multiple light groups defined then this option will save a separate image for each one. Each group is saved by itself with the specified filename and type. The filenames are appended with the name of the specific light group from which it was generated. As before, all tonemapping and other filters are applied for each light group prior to saving.
  • Light Groups to High Dynamic Range Images... - Similar to the previous option only high dynamic range, OpenEXR files are created without tonemapping and other filters applied.
  • Batch Process... - Use this option to convert a directory of .flm files to images. You are prompted to indicate the input directory containing the .flm files and an output directory to store the generated images. You can select either tonemapped or HDR output and can specify if you want to save individual light groups for each file.

Note: for all of these menu entries (except the 'Batch Process') you must first have a rendering in process or have loaded an existing FLM. When executing a Batch process any rendering in process must first be completely stopped and you will be prompted to save the results before continuing. After a batch process the last FLM processed is loaded into the GUI so any unsaved changes will be lost.


  • Resume - this will resume the rendering process after it has been paused
  • Pause - this pauses the rendering process
  • Stop - this stops the rendering process. If you resume after stopping, the render will restart (instead of continuing).

The functionality of this menu can also be accessed by using the buttons at the top left of the render tab.


  • Copy Log - Copies the contents of the log window to the clipboard
  • Clear Log - Deletes all log messages from the Log window
  • Full Screen - Enables full screen mode. Press the hotkey (ESC) to return to normal.
  • Normal Screen - Returns from full screen to a normal window.
  • Overlay Statistics - toggles the visibility of a statistics bar underneath the render image. Note that this bar will not be visible in the exported image.
  • Show Alpha - Toggles a checkerboard background for testing alpha channels.
  • Show Sampling Map - This option does the same as clicking the Refine Brush tab. It shows how luxrender prioritizes areas of the render (white areas being most important). This can be modified by painting the important areas onto the image with the brush tool.
  • Show Side Panel - Toggles the visibility of the left window panels.


The help menu contains self explanatory links to this wiki and other parts of the LuxRender site. The "About" menu item displays a screen with the version of LuxRender you are using along with the names of the developers.

Render Tab

The render tab contains a preview which shows the current results. By default it is updated regularly. It also contains the side pane (see below).

Depending on mode (see above) pressing the left mouse button in the preview area will either pan the image or zoom in on a rectangle. Pressing the middle mouse buttons zooms to fit the screen; the mouse wheel zooms in or out; the right mouse button zooms to 100%.

Render Bar

The render bar, below the tabs, provides quick access to resuming, pausing and stopping the rendering, as well as copying the output image to clipboard. It also displays how many threads LuxRender is currently using for rendering, and allows you to increment or decrement the number of threads.

Imaging Tab

This tab is a part of the side pane of the render tab. It contains various controls to adjust the post-processing of the rendered image. If the "auto" check box is checked (at bottom) adjusting settings will refresh the image immediately. Otherwise you can press the "Apply" button to force a refresh. The "Reset" button will reset the settings to the values given by the scene file.

The triangle on the right hand side of each title bar allows you to collapse or expand that box. Some boxes such as "Lens Effects" have power buttons which allow you to quickly disable and enable all the effects in that box.

  • Tone Mapping - Allows you to change which tonemapping operator is used and it's parameters.
  • Colorspace - Here you can change the color space settings for the output.
  • Gamma + Film Response - Allows you to change the gamma of the image.
  • HDR Histogram - Displays a histogram of the output image.
  • Lens Effects - Allows you to apply various lens effects to the image, such as bloom and vignetting. These are best applied when the render is finished, as some are quite time consuming to apply.
  • Noise Reduction - Allows you to apply noise reduction to the output. As with lens effects it's best to apply these when the render is finished.

Light Groups Tab

This tab is a part of the side pane of the render tab. It contains controls to adjust the light group parameters for any light groups in the scene. See the Light Groups page for more information on how to use light groups.

Refine Bursh Tab

This tab allows you to brush areas of the image that are most important. LuxRender will focus its effort to render that area more than its surroundings. The Apply button must be pressed for any change to have an effect.

  • Add Importance Pen - Allows you to brush areas that are important.
  • Sub. Importance Pen - Allows you to subtract areas that have been brushed.
  • Pen size - Adjusts the size of the brush
  • Pen strength - Adjusts the intensity of the brush. Higher values produces harder strokes.
  • Overlay opacity - Adjusts the visual appearance of the brushed areas. Useful when the white overlay is too bright.
  • Reset - Removes all brush strokes and reverts to having everything equally important in the render.
  • Undo - Undoes the last brush stroke.
  • Apply - Every time you use a brush, this button has to be pressed before LuxRender implements the changes.

Advanced Tab

This tab just has somewhat verbose information about the renderer and film settings.

Network Tab

This tab allows you to connect or disconnect network servers and shows you information about any connected ones. See the Network rendering page for more info.

Log Tab

This tab shows log messages that are shown during the rendering process, including:

  • Warnings about incorrect usage
  • Information about loaded bitmap images
  • Information about progress of the rendering progress
  • Information about writing output messages

Status Bar

The status bar, located at the bottom, displays information about the state of your rendering; from left to right:

  • Status of LuxRender at this moment (rendering, paused, stopped.. etc).
  • Activity: what LuxRender is doing (rendering or tonemapping)
  • Progress bar when the render is timed.

The Statistics portion of the status bar shows the following information:

  • Total rendering time that has passed.
  • CPU threads used for rendering
  • "S/p" stands for "Samples per pixel" and is the average number of samples calculated per pixel of the output image.
  • "S/s" stands for "Samples per second" and is an instantaneous measure of your current rendering speed.
  • "MC/s" (todo)
  • "Eff" stands for efficiency of the rendering process. 250% means there's on average 2.5 light contributions per sample. See here for more details. If this number is very low (below 100%), LuxRender has a hard time finding the light and it may help to try different rendering settings.