Color Matrix Node

Color Matrix exposes an editable 4×4 matrix - the same kind shaders use for color transformations. The identity matrix changes nothing; by editing the coefficients, you build effects such as sepia, weighted B&W, channel swaps or inversions.

Powerful for people who think in coefficients. Less intuitive than a Color Corrector for classic grading - prefer it for "exotic" or reproducible transformations (a matrix is easy to copy/share).

• Effects Library: Tools > Color > Color Matrix
• Quick add: right-click in the Node Editor → Add Tool > Color > Color Matrix

• Input (orange) - required. The 2D image to transform.
• Effect Mask (blue) - optional. Limits the transformation to an area.

MediaIn → Color Matrix → Merge 2D → Saver

Each output channel is computed as:

[R out] = cRR × [R in] + cRG × [G in] + cRB × [B in] + cRA × [A in] + offsetR
[G out] = cGR × [R in] + cGG × [G in] + cGB × [B in] + cGA × [A in] + offsetG
[B out] = cBR × [R in] + cBG × [G in] + cBB × [B in] + cBA × [A in] + offsetB
[A out] = cAR × [R in] + cAG × [G in] + cAB × [B in] + cAA × [A in] + offsetA

Structure of the matrix in the Inspector:

• Rows = output channels: R, G, B, A.
• Columns = input channels: R, G, B, A + an Add column (constant offset).

The identity matrix (default):

        R   G   B   A   Add
R out:  1   0   0   0    0     → R out = R in (unchanged)
G out:  0   1   0   0    0     → G out = G in
B out:  0   0   1   0    0     → B out = B in
A out:  0   0   0   1    0     → A out = A in

This matrix copies each input channel to the matching output channel, without any change.

Update Lock

Temporarily disables rendering while you edit the matrix. Useful if every change triggers a heavy recalculation. Turn it back on once the matrix is set.

Matrix

A 4-row × 5-column grid (RGBA + Add) to edit. All the coefficients are floats - negative values are possible (to subtract), > 1 is possible (to amplify).

Invert

Inverts the matrix (computes the inverse matrix). Lets you cancel the effect of a Color Matrix downstream, the equivalent of a chained undo. Warning: if the matrix is singular (not invertible, e.g. all zeros on a row), the inversion fails.

Weighted B&W (standard Rec.709 luminance)

Each output channel is a weighted combination of the source RGB, giving a perceptually correct luminance:

        R      G      B      A   Add
R out: 0.2126 0.7152 0.0722  0    0
G out: 0.2126 0.7152 0.0722  0    0
B out: 0.2126 0.7152 0.0722  0    0
A out:  0      0      0      1    0

The 3 RGB rows are identical → each output pixel has R=G=B → a grayscale image. The coefficients 0.2126 / 0.7152 / 0.0722 reflect human sensitivity (green dominates).

Sepia

        R      G      B      A   Add
R out: 0.393  0.769  0.189   0    0
G out: 0.349  0.686  0.168   0    0
B out: 0.272  0.534  0.131   0    0
A out:  0      0      0      1    0

Channel swap (Red ↔ Blue)

        R   G   B   A   Add
R out:  0   0   1   0    0   (Red out = Blue in)
G out:  0   1   0   0    0   (Green unchanged)
B out:  1   0   0   0    0   (Blue out = Red in)
A out:  0   0   0   1    0

Negative (color inversion)

        R   G   B   A   Add
R out: -1   0   0   0    1   (1 - R)
G out:  0  -1   0   0    1
B out:  0   0  -1   0    1
A out:  0   0   0   1    0

Global tint (warm cast)

        R   G   B   A   Add
R out:  1   0   0   0   0.1   (+10% red everywhere)
G out:  0   1   0   0   0.05  (+5% green)
B out:  0   0   1   0    0
A out:  0   0   0   1    0

• Channel swap - swap R and B to debug a shot that arrives with inverted channels (typical of badly made BMP imports).
• Scientific B&W - Rec.709 weighted luminance instead of a naive desaturation. Preserves the correct tonal hierarchy.
• Faithful sepia effect - a recognized mathematical formula (used in Photoshop, After Effects).
• Reproducible stylized look - a custom matrix can be saved and reapplied identically to other shots (more reliable than a Color Corrector with many parameters).
• Full negative - negative coefficients + offsets = a pure inversion.
• Uniform color cast - the Add column lets you add a uniform color to every pixel (≠ a tint, which multiplies).

• Matrix thinking vs slider thinking - if you do not naturally think in coefficients, Color Matrix is intimidating. For standard grading, prefer Color Corrector.
• Perfect reproducibility - a matrix is 20 coefficients, easy to store as a preset or share between projects. It is the tool of choice for signature looks.
• Invert is fragile - if a row is all zeros, the matrix is no longer invertible. For a real "undo", save your state and restore it instead.
• Update Lock on complex scenes - turn it on when you edit several cells and the render recalculates on every change.
• Matrix = linear transformation - it cannot do non-linear operations (gamma, S-curve). For that, use Color Curves.
• To extract a perceptual luminance somewhere in a flow, the B&W Color Matrix is faster than a Color Corrector in desaturation mode.