Viewer

The Viewer node displays the render output of any connected process nodes in the Viewer panel. It doesn’t alter data in any way, but simply allows you to view the effect of any changes you make upstream.

You can place as many Viewer nodes in a script as you wish, which allows you to simultaneously view multiple outputs. You can also connect the output from up to ten process nodes into single Viewer node, and then cycle through the various displays. This allows you to easily compare an image before and after processing by a given effect.

Inputs and Controls

Connection Type	Connection Name	Function
Input	unnamed	The process node upstream to output to the Viewer. You can connect up to ten (0-9) nodes at once.

Control (UI)	Knob (Scripting)	Default Value	Function
Viewer Tab
frame_range	frame_range	none	Sets the first and last frame in the playback range. You can enter frame numbers here or Cmd+drag the red triangles in the timeline.
frame_range	frame_range_lock	enabled	Click to unlock or lock playback to the frame numbers specified in frame_range.
<< >>increment	frame_increment	10	Sets the number of frames to step through using the Viewer << and >> buttons.
channels	channels	rgba	Sets the channels to display in the viewer. You can also select a channel from a different layer to display in the alpha channel.
channels	cliptest	disabled	When enabled, any pixels that are outside the 0-1 range are Zebra-striped in the Viewer.
gain	gain	1	Sets the amount of gain to multiply the image by before display.
gamma	gamma	1	Sets the amount of gamma correction to apply to the image. Gamma correction is applied after the gain, viewerprocess, and any custom inputprocess.
apply LUT to color channels only	rgb_only	disabled	When enabled, the LUT is applied to color channels only.
downrez	downrez	1	Sets the amount of down scaling applied before display. factor to speed up rendering. You can use downrez to speed up rendering, but bear in mind that it is multiplied into any global proxy scale that may also be in effect.
ignore pixel aspect	ignore_pixel_aspect	disabled	When enabled, output to the Viewer ignores the file’s pixel aspect ratio and always draws using square pixels.
prevent auto zoom	zoom_lock	disabled	When enabled, the Viewer is prevented from automatically adjusting the zoom level to fit new images into the Viewer when swapping between different sized images.
show overscan	show_overscan	disabled	When enabled, any overscan present is displayed in the Viewer.
overscan	overscan	100	Sets the amount of overscan to show in the Viewer when show overscan ins enabled.
center f-stop	center_fstop	8	Sets the f-stop to display when gain is set to 1. You can use zero to show stops as +/-n. NOTE: If you want a non-integer value, enter a formula to get an accurate value, otherwise the display does not round to normal f-stop names. For instance, instead of 5.6 you would use pow(2,2.5) to get 5.65685
shutter angle	shutter_angle	180	Sets the camera shutter angle from 0-360 degrees. This is used in combination with the Viewer's playback fps setting to compute exposure values.
gl buffer depth	gl_buffer_depth	float	Sets the OpenGL buffer depth and enables the use of the GPU for the Viewer process and input process: • byte - converts to 8-bit with error diffusion. • half-float - converts to 16-bit (half) float. • float - uses a full 32-bit floating point texture (may be very slow on some cards). In half and full float modes, the GPU can be used to apply Viewer effects like gamma and the LUT in a Viewer process. NOTE: You can choose a default value for this setting in the Preferences or by using knobDefault() in a startup script.
use GPU for viewer when possible	useGPUForViewer	enabled	When enabled, Viewer effects (like gain, gamma, and viewer process node) are applied using the GPU when possible. The ’when possible’ clause is due to the fact that in some cases, like when broadcast monitor output is enabled or the GL buffer depth is 8-bit, effects must be computed in the CPU.
use GPU for input when possible	useGPUForInputs	enabled	When enabled, compute nodes connected to the Viewer input on the GPU when possible, though not all nodes have a GPU implementation. Normally, the Viewer only attempts to run its own effects (like gain, gamma, and viewer process node) on the GPU. NOTE: If nodes are computed on the GPU, the color values displayed in the Viewer are inaccurate since they show the color from the last node computed in the CPU, prior to transferring the image into the graphics card.
disabled GPU dithering	disableGPUDitherForViewer	disabled	When enabled, GPU dithering is allowed in the Viewer (which affects half-float and float modes).
viewer process	viewerProcess	sRGB	Sets the Viewer Process operation applied to the viewed image before it is displayed on the screen. It is typically used to convert from linear to your monitor's colorspace.
input process	input_process_node	VIEWER_INPUT	Sets the name of a node to process through for viewing when the IP button is activated. If the node does not exist, the IP button has no effect.
input process	input_process	disabled	Applies the input process node before displaying the image. To define the node to use, enter its name in the input process field or, from the Node Graph right-click menu, select Edit > Node > Use as Input Process.
input process order	viewerInputOrder	before viewer process	Sets when the input process node specified is applied: • before viewer process. • after viewer process.
enable monitor output	MonitorOutEnable	disabled	When enabled, the Viewer is output to the connected monitor device. NOTE: You cannot enable this control if no monitor output device is specified.
monitor output device	MonitorOutDevice	None	Sets the monitor output device to receive the Viewer output: • None • Digital Cinema Desktop • Firewire
monitor output mode	MonitorOutMode	-	Sets the display mode for the specified monitor output device: • none - no selections are available. • D - select a Digital output device from the dropdown. • A - select a Firewire output device from the dropdown.
3D Tab
grid position xyz	grid_origin	0, 0, 0	Sets the position of the grid in the 3D Viewer on the x, y, and z axes.
display	display	unchanged	Adjust the display characteristics of 3D objects. These settings don’t affect the render output of the scene; these are for display purposes only in the 3D Viewer. • off - hides all 3D objects. • wireframe - displays only the outlines of object geometry. • solid - displays all object geometry with a solid color. • solid+lines - displays the geometry as solid color with individual object’s geometry outlines. • textured - displays only the surface texture of objects. • textured+lines - displays the wireframe plus the surface texture. • unchanged - doesn't change object display modes. NOTE: This setting can override individual object settings.
transparency	use_alpha	enabled	When enabled, objects appear transparent where their alpha is < 1.
headlamp	gl_lighting	disabled	When enabled, objects are shaded with a spotlight attached to the viewpoint to make their shape visible.
alpha clipping	gl_alpha_clip	1	Sets the alpha value used by the transparency control which determines if an object is opaque or not.
polygon offset	gl_poly_offset	1	Sets the visibility of lines in hidden-line mode.
show	show_points	disabled	When enabled, all points are displayed in the 3D Viewer.
	show_point_num	disabled	When enabled, all points are numbered in the 3D Viewer.
	show_point_info	disabled	When enabled, all points are labeled with xyz coordinates in the 3D Viewer.
	show_point_normals	disabled	When enabled, all available point normals are displayed in the 3D Viewer.
	show_point_uvs	disabled	When enabled, all available point uvs are displayed in the 3D Viewer.
	show_vertex_num	disabled	When enabled, all vertices are labeled in the 3D Viewer.
	show_vertex_normals	disabled	When enabled, all available vertex normals are displayed in the 3D Viewer.
	show_vertex_uvs	disabled	When enabled, all available vertex uvs are displayed in the 3D Viewer.
	show_prim_num	disabled	When enabled, all primitives are labeled in the 3D Viewer.
	show_prim_normals	disabled	When enabled, all primitive normals are labeled in the 3D Viewer.
	show_prim_bbox	disabled	When enabled, all primitive bounding boxes are labeled in the 3D Viewer.
	grid_display	enabled	When enabled, a grid displays in the 3D Viewer.
default lens	default_lens	1	Sets the default lens (focal length divided by film width) to use in 3D mode when no camera is selected.
near	near	0.1	Sets the limit of the OpenGL near clipping plane. Objects closer to the camera that this value are not rendered the 3D Viewer.
far	far	1000	Sets the limit of the OpenGL far clipping plane. Objects farther away from the camera that this value are not rendered the 3D Viewer. The far clipping plane can be moved farther away if objects in the scene are farther away. In this case, the near plane is also moved so that the ratio between near and far planes is preserved.