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Histogram

Histogram graphs the number of pixels at each brightness level. This is a useful gauge to see whether the input image has a good distribution of shadows, midtones, and highlights.

You can also use this node to adjust the tonal range of the input image. Note, however, that Histogram clamps superblacks and superwhites. If you don’t want this to happen, use the Grade node instead.

TIP: You can also use the histogram panel available in the content menu under Scope > Histogram.

Inputs and Controls

Connection Type	Connection Name	Function
Input	unnamed	The image sequence whose tonal range you want to examine or adjust.
mask	An optional image to use as a mask. By default, the color correction is limited to the non-black areas of the mask. At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Connection Type

Connection Name

Function

Input

unnamed

The image sequence whose tonal range you want to examine or adjust.

mask

An optional image to use as a mask. By default, the color correction is limited to the non-black areas of the mask.

At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Control (UI)	Knob (Scripting)	Default Value	Function
Histogram Tab
Histogram	hist	N/A	The horizontal axis represents brightness (the numerical value of a pixel), with the shadows on the left, midtones in the middle, and highlights on the right. The vertical axis represents pixel count (the percentage of pixels with that value).
input range	in	0, 1, 1	Allows you to extend the image’s tonal range, which has the effect of increasing contrast. To set the black point, drag the leftmost input range slider till it roughly lines up with the initial boundary of the histogram. This makes shadows darker. To set the white point, drag the rightmost input range slider till it roughly lines up with the final boundary of the histogram. This makes highlights lighter. To set the midtone, or neutral, value, drag the middle input slider. This applies a gamma correction (lightens or darkens the midtones). The histogram updates as you adjust these controls.
output range	out	0, 1	Sets the range to which the input range is mapped. This can be used to shorten the image’s tonal range, which has the effect of removing pure black and white and decreasing contrast. Any pixels that are black are set to the value on the left. This makes shadows lighter. Any pixels that are white are set to the value on the right. This makes highlights darker. The histogram updates as you adjust these controls.
mask	N/A	disabled	Enables the associated mask channel to the right. Disabling this checkbox is the same as setting the channel to none.
mask	maskChannelInput	none	The channel to use as a mask. By default, the color correction is limited to the non-black areas of this channel.
inject	inject	disabled	Copies the mask input to the predefined mask.a channel. Injecting the mask allows you to use the same mask further downstream.
invert	invert_mask	disabled	Inverts the use of the mask channel so that the color correction is limited to the non-white areas of the mask.
fringe	fringe	disabled	Blurs the edges of the mask.
(un)premult by	N/A	disabled	Enables the associated channel to the right. Disabling this checkbox is the same as setting the channel to none.
(un)premult by	unpremult	none	The image is divided by this channel before being processed, and multiplied again afterwards. If you are using premultiplied input images, you may want to check (un)premult by and select rgba.alpha here. This will simulate doing the color correction before the premultiplication was done. It is the same as adding an Unpremult node before this node and a Premult node after, but allows you to work faster if you’re only using one color correct node. If you are using unpremultiplied input images, you should leave this set to none.
invert	invert_unpremult	disabled	Inverts the use of the (un)premultiply channel.
mix	mix	1	Dissolves between the original image at 0 and the full color correction at 1.